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SubjectRe: [PATCH v4 2/2] drm/xen-front: Add support for Xen PV display frontend
On Wed, Mar 28, 2018 at 09:47:41AM +0300, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Add support for Xen para-virtualized frontend display driver.
> Accompanying backend [1] is implemented as a user-space application
> and its helper library [2], capable of running as a Weston client
> or DRM master.
> Configuration of both backend and frontend is done via
> Xen guest domain configuration options [3].
>
> Driver limitations:
> 1. Only primary plane without additional properties is supported.
> 2. Only one video mode supported which resolution is configured via XenStore.
> 3. All CRTCs operate at fixed frequency of 60Hz.
>
> 1. Implement Xen bus state machine for the frontend driver according to
> the state diagram and recovery flow from display para-virtualized
> protocol: xen/interface/io/displif.h.
>
> 2. Read configuration values from Xen store according
> to xen/interface/io/displif.h protocol:
> - read connector(s) configuration
> - read buffer allocation mode (backend/frontend)
>
> 3. Handle Xen event channels:
> - create for all configured connectors and publish
> corresponding ring references and event channels in Xen store,
> so backend can connect
> - implement event channels interrupt handlers
> - create and destroy event channels with respect to Xen bus state
>
> 4. Implement shared buffer handling according to the
> para-virtualized display device protocol at xen/interface/io/displif.h:
> - handle page directories according to displif protocol:
> - allocate and share page directories
> - grant references to the required set of pages for the
> page directory
> - allocate xen balllooned pages via Xen balloon driver
> with alloc_xenballooned_pages/free_xenballooned_pages
> - grant references to the required set of pages for the
> shared buffer itself
> - implement pages map/unmap for the buffers allocated by the
> backend (gnttab_map_refs/gnttab_unmap_refs)
>
> 5. Implement kernel modesetiing/connector handling using
> DRM simple KMS helper pipeline:
>
> - implement KMS part of the driver with the help of DRM
> simple pipepline helper which is possible due to the fact
> that the para-virtualized driver only supports a single
> (primary) plane:
> - initialize connectors according to XenStore configuration
> - handle frame done events from the backend
> - create and destroy frame buffers and propagate those
> to the backend
> - propagate set/reset mode configuration to the backend on display
> enable/disable callbacks
> - send page flip request to the backend and implement logic for
> reporting backend IO errors on prepare fb callback
>
> - implement virtual connector handling:
> - support only pixel formats suitable for single plane modes
> - make sure the connector is always connected
> - support a single video mode as per para-virtualized driver
> configuration
>
> 6. Implement GEM handling depending on driver mode of operation:
> depending on the requirements for the para-virtualized environment, namely
> requirements dictated by the accompanying DRM/(v)GPU drivers running in both
> host and guest environments, number of operating modes of para-virtualized
> display driver are supported:
> - display buffers can be allocated by either frontend driver or backend
> - display buffers can be allocated to be contiguous in memory or not
>
> Note! Frontend driver itself has no dependency on contiguous memory for
> its operation.
>
> 6.1. Buffers allocated by the frontend driver.
>
> The below modes of operation are configured at compile-time via
> frontend driver's kernel configuration.
>
> 6.1.1. Front driver configured to use GEM CMA helpers
> This use-case is useful when used with accompanying DRM/vGPU driver in
> guest domain which was designed to only work with contiguous buffers,
> e.g. DRM driver based on GEM CMA helpers: such drivers can only import
> contiguous PRIME buffers, thus requiring frontend driver to provide
> such. In order to implement this mode of operation para-virtualized
> frontend driver can be configured to use GEM CMA helpers.
>
> 6.1.2. Front driver doesn't use GEM CMA
> If accompanying drivers can cope with non-contiguous memory then, to
> lower pressure on CMA subsystem of the kernel, driver can allocate
> buffers from system memory.
>
> Note! If used with accompanying DRM/(v)GPU drivers this mode of operation
> may require IOMMU support on the platform, so accompanying DRM/vGPU
> hardware can still reach display buffer memory while importing PRIME
> buffers from the frontend driver.
>
> 6.2. Buffers allocated by the backend
>
> This mode of operation is run-time configured via guest domain configuration
> through XenStore entries.
>
> For systems which do not provide IOMMU support, but having specific
> requirements for display buffers it is possible to allocate such buffers
> at backend side and share those with the frontend.
> For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting
> physically contiguous memory, this allows implementing zero-copying
> use-cases.
>
> Note, while using this scenario the following should be considered:
> a) If guest domain dies then pages/grants received from the backend
> cannot be claimed back
> b) Misbehaving guest may send too many requests to the
> backend exhausting its grant references and memory
> (consider this from security POV).
>
> Note! Configuration options 1.1 (contiguous display buffers) and 2 (backend
> allocated buffers) are not supported at the same time.
>
> 7. Handle communication with the backend:
> - send requests and wait for the responses according
> to the displif protocol
> - serialize access to the communication channel
> - time-out used for backend communication is set to 3000 ms
> - manage display buffers shared with the backend
>
> [1] https://github.com/xen-troops/displ_be
> [2] https://github.com/xen-troops/libxenbe
> [3] https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/man/xl.cfg.pod.5.in;h=a699367779e2ae1212ff8f638eff0206ec1a1cc9;hb=refs/heads/master#l1257
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

kms side looks good now too.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
> Documentation/gpu/drivers.rst | 1 +
> Documentation/gpu/xen-front.rst | 43 ++
> drivers/gpu/drm/Kconfig | 2 +
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/xen/Kconfig | 30 +
> drivers/gpu/drm/xen/Makefile | 16 +
> drivers/gpu/drm/xen/xen_drm_front.c | 880 ++++++++++++++++++++++++++++
> drivers/gpu/drm/xen/xen_drm_front.h | 189 ++++++
> drivers/gpu/drm/xen/xen_drm_front_cfg.c | 77 +++
> drivers/gpu/drm/xen/xen_drm_front_cfg.h | 37 ++
> drivers/gpu/drm/xen/xen_drm_front_conn.c | 115 ++++
> drivers/gpu/drm/xen/xen_drm_front_conn.h | 27 +
> drivers/gpu/drm/xen/xen_drm_front_evtchnl.c | 382 ++++++++++++
> drivers/gpu/drm/xen/xen_drm_front_evtchnl.h | 81 +++
> drivers/gpu/drm/xen/xen_drm_front_gem.c | 309 ++++++++++
> drivers/gpu/drm/xen/xen_drm_front_gem.h | 41 ++
> drivers/gpu/drm/xen/xen_drm_front_gem_cma.c | 78 +++
> drivers/gpu/drm/xen/xen_drm_front_kms.c | 371 ++++++++++++
> drivers/gpu/drm/xen/xen_drm_front_kms.h | 27 +
> drivers/gpu/drm/xen/xen_drm_front_shbuf.c | 432 ++++++++++++++
> drivers/gpu/drm/xen/xen_drm_front_shbuf.h | 72 +++
> 21 files changed, 3211 insertions(+)
> create mode 100644 Documentation/gpu/xen-front.rst
> create mode 100644 drivers/gpu/drm/xen/Kconfig
> create mode 100644 drivers/gpu/drm/xen/Makefile
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front.h
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_cfg.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_cfg.h
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_conn.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_conn.h
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_evtchnl.h
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem.h
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_kms.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_kms.h
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.c
> create mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.h
>
> diff --git a/Documentation/gpu/drivers.rst b/Documentation/gpu/drivers.rst
> index e8c84419a2a1..d3ab6abae838 100644
> --- a/Documentation/gpu/drivers.rst
> +++ b/Documentation/gpu/drivers.rst
> @@ -12,6 +12,7 @@ GPU Driver Documentation
> tve200
> vc4
> bridge/dw-hdmi
> + xen-front
>
> .. only:: subproject and html
>
> diff --git a/Documentation/gpu/xen-front.rst b/Documentation/gpu/xen-front.rst
> new file mode 100644
> index 000000000000..8188e03c9d23
> --- /dev/null
> +++ b/Documentation/gpu/xen-front.rst
> @@ -0,0 +1,43 @@
> +====================================
> +Xen para-virtualized frontend driver
> +====================================
> +
> +This frontend driver implements Xen para-virtualized display
> +according to the display protocol described at
> +include/xen/interface/io/displif.h
> +
> +Driver modes of operation in terms of display buffers used
> +==========================================================
> +
> +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
> + :doc: Driver modes of operation in terms of display buffers used
> +
> +Buffers allocated by the frontend driver
> +----------------------------------------
> +
> +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
> + :doc: Buffers allocated by the frontend driver
> +
> +With GEM CMA helpers
> +~~~~~~~~~~~~~~~~~~~~
> +
> +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
> + :doc: With GEM CMA helpers
> +
> +Without GEM CMA helpers
> +~~~~~~~~~~~~~~~~~~~~~~~
> +
> +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
> + :doc: Without GEM CMA helpers
> +
> +Buffers allocated by the backend
> +--------------------------------
> +
> +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
> + :doc: Buffers allocated by the backend
> +
> +Driver limitations
> +==================
> +
> +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h
> + :doc: Driver limitations
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index deeefa7a1773..757825ac60df 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -289,6 +289,8 @@ source "drivers/gpu/drm/pl111/Kconfig"
>
> source "drivers/gpu/drm/tve200/Kconfig"
>
> +source "drivers/gpu/drm/xen/Kconfig"
> +
> # Keep legacy drivers last
>
> menuconfig DRM_LEGACY
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 50093ff4479b..9d66657ea117 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -103,3 +103,4 @@ obj-$(CONFIG_DRM_MXSFB) += mxsfb/
> obj-$(CONFIG_DRM_TINYDRM) += tinydrm/
> obj-$(CONFIG_DRM_PL111) += pl111/
> obj-$(CONFIG_DRM_TVE200) += tve200/
> +obj-$(CONFIG_DRM_XEN) += xen/
> diff --git a/drivers/gpu/drm/xen/Kconfig b/drivers/gpu/drm/xen/Kconfig
> new file mode 100644
> index 000000000000..4f4abc91f3b6
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/Kconfig
> @@ -0,0 +1,30 @@
> +config DRM_XEN
> + bool "DRM Support for Xen guest OS"
> + depends on XEN
> + help
> + Choose this option if you want to enable DRM support
> + for Xen.
> +
> +config DRM_XEN_FRONTEND
> + tristate "Para-virtualized frontend driver for Xen guest OS"
> + depends on DRM_XEN
> + depends on DRM
> + select DRM_KMS_HELPER
> + select VIDEOMODE_HELPERS
> + select XEN_XENBUS_FRONTEND
> + help
> + Choose this option if you want to enable a para-virtualized
> + frontend DRM/KMS driver for Xen guest OSes.
> +
> +config DRM_XEN_FRONTEND_CMA
> + bool "Use DRM CMA to allocate dumb buffers"
> + depends on DRM_XEN_FRONTEND
> + select DRM_KMS_CMA_HELPER
> + select DRM_GEM_CMA_HELPER
> + help
> + Use DRM CMA helpers to allocate display buffers.
> + This is useful for the use-cases when guest driver needs to
> + share or export buffers to other drivers which only expect
> + contiguous buffers.
> + Note: in this mode driver cannot use buffers allocated
> + by the backend.
> diff --git a/drivers/gpu/drm/xen/Makefile b/drivers/gpu/drm/xen/Makefile
> new file mode 100644
> index 000000000000..352730dc6c13
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/Makefile
> @@ -0,0 +1,16 @@
> +# SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +drm_xen_front-objs := xen_drm_front.o \
> + xen_drm_front_kms.o \
> + xen_drm_front_conn.o \
> + xen_drm_front_evtchnl.o \
> + xen_drm_front_shbuf.o \
> + xen_drm_front_cfg.o
> +
> +ifeq ($(CONFIG_DRM_XEN_FRONTEND_CMA),y)
> + drm_xen_front-objs += xen_drm_front_gem_cma.o
> +else
> + drm_xen_front-objs += xen_drm_front_gem.o
> +endif
> +
> +obj-$(CONFIG_DRM_XEN_FRONTEND) += drm_xen_front.o
> diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
> new file mode 100644
> index 000000000000..b08817e5e35c
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front.c
> @@ -0,0 +1,880 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_gem.h>
> +#include <drm/drm_gem_cma_helper.h>
> +
> +#include <linux/of_device.h>
> +
> +#include <xen/platform_pci.h>
> +#include <xen/xen.h>
> +#include <xen/xenbus.h>
> +
> +#include <xen/interface/io/displif.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_cfg.h"
> +#include "xen_drm_front_evtchnl.h"
> +#include "xen_drm_front_gem.h"
> +#include "xen_drm_front_kms.h"
> +#include "xen_drm_front_shbuf.h"
> +
> +struct xen_drm_front_dbuf {
> + struct list_head list;
> + uint64_t dbuf_cookie;
> + uint64_t fb_cookie;
> + struct xen_drm_front_shbuf *shbuf;
> +};
> +
> +static int dbuf_add_to_list(struct xen_drm_front_info *front_info,
> + struct xen_drm_front_shbuf *shbuf, uint64_t dbuf_cookie)
> +{
> + struct xen_drm_front_dbuf *dbuf;
> +
> + dbuf = kzalloc(sizeof(*dbuf), GFP_KERNEL);
> + if (!dbuf)
> + return -ENOMEM;
> +
> + dbuf->dbuf_cookie = dbuf_cookie;
> + dbuf->shbuf = shbuf;
> + list_add(&dbuf->list, &front_info->dbuf_list);
> + return 0;
> +}
> +
> +static struct xen_drm_front_dbuf *dbuf_get(struct list_head *dbuf_list,
> + uint64_t dbuf_cookie)
> +{
> + struct xen_drm_front_dbuf *buf, *q;
> +
> + list_for_each_entry_safe(buf, q, dbuf_list, list)
> + if (buf->dbuf_cookie == dbuf_cookie)
> + return buf;
> +
> + return NULL;
> +}
> +
> +static void dbuf_flush_fb(struct list_head *dbuf_list, uint64_t fb_cookie)
> +{
> + struct xen_drm_front_dbuf *buf, *q;
> +
> + list_for_each_entry_safe(buf, q, dbuf_list, list)
> + if (buf->fb_cookie == fb_cookie)
> + xen_drm_front_shbuf_flush(buf->shbuf);
> +}
> +
> +static void dbuf_free(struct list_head *dbuf_list, uint64_t dbuf_cookie)
> +{
> + struct xen_drm_front_dbuf *buf, *q;
> +
> + list_for_each_entry_safe(buf, q, dbuf_list, list)
> + if (buf->dbuf_cookie == dbuf_cookie) {
> + list_del(&buf->list);
> + xen_drm_front_shbuf_unmap(buf->shbuf);
> + xen_drm_front_shbuf_free(buf->shbuf);
> + kfree(buf);
> + break;
> + }
> +}
> +
> +static void dbuf_free_all(struct list_head *dbuf_list)
> +{
> + struct xen_drm_front_dbuf *buf, *q;
> +
> + list_for_each_entry_safe(buf, q, dbuf_list, list) {
> + list_del(&buf->list);
> + xen_drm_front_shbuf_unmap(buf->shbuf);
> + xen_drm_front_shbuf_free(buf->shbuf);
> + kfree(buf);
> + }
> +}
> +
> +static struct xendispl_req *be_prepare_req(
> + struct xen_drm_front_evtchnl *evtchnl, uint8_t operation)
> +{
> + struct xendispl_req *req;
> +
> + req = RING_GET_REQUEST(&evtchnl->u.req.ring,
> + evtchnl->u.req.ring.req_prod_pvt);
> + req->operation = operation;
> + req->id = evtchnl->evt_next_id++;
> + evtchnl->evt_id = req->id;
> + return req;
> +}
> +
> +static int be_stream_do_io(struct xen_drm_front_evtchnl *evtchnl,
> + struct xendispl_req *req)
> +{
> + reinit_completion(&evtchnl->u.req.completion);
> + if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
> + return -EIO;
> +
> + xen_drm_front_evtchnl_flush(evtchnl);
> + return 0;
> +}
> +
> +static int be_stream_wait_io(struct xen_drm_front_evtchnl *evtchnl)
> +{
> + if (wait_for_completion_timeout(&evtchnl->u.req.completion,
> + msecs_to_jiffies(XEN_DRM_FRONT_WAIT_BACK_MS)) <= 0)
> + return -ETIMEDOUT;
> +
> + return evtchnl->u.req.resp_status;
> +}
> +
> +int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,
> + uint32_t x, uint32_t y, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t fb_cookie)
> +{
> + struct xen_drm_front_evtchnl *evtchnl;
> + struct xen_drm_front_info *front_info;
> + struct xendispl_req *req;
> + unsigned long flags;
> + int ret;
> +
> + front_info = pipeline->drm_info->front_info;
> + evtchnl = &front_info->evt_pairs[pipeline->index].req;
> + if (unlikely(!evtchnl))
> + return -EIO;
> +
> + mutex_lock(&evtchnl->u.req.req_io_lock);
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + req = be_prepare_req(evtchnl, XENDISPL_OP_SET_CONFIG);
> + req->op.set_config.x = x;
> + req->op.set_config.y = y;
> + req->op.set_config.width = width;
> + req->op.set_config.height = height;
> + req->op.set_config.bpp = bpp;
> + req->op.set_config.fb_cookie = fb_cookie;
> +
> + ret = be_stream_do_io(evtchnl, req);
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> + if (ret == 0)
> + ret = be_stream_wait_io(evtchnl);
> +
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + return ret;
> +}
> +
> +static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t size, struct page **pages,
> + struct sg_table *sgt)
> +{
> + struct xen_drm_front_evtchnl *evtchnl;
> + struct xen_drm_front_shbuf *shbuf;
> + struct xendispl_req *req;
> + struct xen_drm_front_shbuf_cfg buf_cfg;
> + unsigned long flags;
> + int ret;
> +
> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
> + if (unlikely(!evtchnl))
> + return -EIO;
> +
> + memset(&buf_cfg, 0, sizeof(buf_cfg));
> + buf_cfg.xb_dev = front_info->xb_dev;
> + buf_cfg.pages = pages;
> + buf_cfg.size = size;
> + buf_cfg.sgt = sgt;
> + buf_cfg.be_alloc = front_info->cfg.be_alloc;
> +
> + shbuf = xen_drm_front_shbuf_alloc(&buf_cfg);
> + if (!shbuf)
> + return -ENOMEM;
> +
> + ret = dbuf_add_to_list(front_info, shbuf, dbuf_cookie);
> + if (ret < 0) {
> + xen_drm_front_shbuf_free(shbuf);
> + return ret;
> + }
> +
> + mutex_lock(&evtchnl->u.req.req_io_lock);
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_CREATE);
> + req->op.dbuf_create.gref_directory =
> + xen_drm_front_shbuf_get_dir_start(shbuf);
> + req->op.dbuf_create.buffer_sz = size;
> + req->op.dbuf_create.dbuf_cookie = dbuf_cookie;
> + req->op.dbuf_create.width = width;
> + req->op.dbuf_create.height = height;
> + req->op.dbuf_create.bpp = bpp;
> + if (buf_cfg.be_alloc)
> + req->op.dbuf_create.flags |= XENDISPL_DBUF_FLG_REQ_ALLOC;
> +
> + ret = be_stream_do_io(evtchnl, req);
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> + if (ret < 0)
> + goto fail;
> +
> + ret = be_stream_wait_io(evtchnl);
> + if (ret < 0)
> + goto fail;
> +
> + ret = xen_drm_front_shbuf_map(shbuf);
> + if (ret < 0)
> + goto fail;
> +
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + return 0;
> +
> +fail:
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + dbuf_free(&front_info->dbuf_list, dbuf_cookie);
> + return ret;
> +}
> +
> +int xen_drm_front_dbuf_create_from_sgt(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t size, struct sg_table *sgt)
> +{
> + return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
> + bpp, size, NULL, sgt);
> +}
> +
> +int xen_drm_front_dbuf_create_from_pages(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t size, struct page **pages)
> +{
> + return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
> + bpp, size, pages, NULL);
> +}
> +
> +static int xen_drm_front_dbuf_destroy(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie)
> +{
> + struct xen_drm_front_evtchnl *evtchnl;
> + struct xendispl_req *req;
> + unsigned long flags;
> + bool be_alloc;
> + int ret;
> +
> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
> + if (unlikely(!evtchnl))
> + return -EIO;
> +
> + be_alloc = front_info->cfg.be_alloc;
> +
> + /*
> + * For the backend allocated buffer release references now, so backend
> + * can free the buffer.
> + */
> + if (be_alloc)
> + dbuf_free(&front_info->dbuf_list, dbuf_cookie);
> +
> + mutex_lock(&evtchnl->u.req.req_io_lock);
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_DESTROY);
> + req->op.dbuf_destroy.dbuf_cookie = dbuf_cookie;
> +
> + ret = be_stream_do_io(evtchnl, req);
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> + if (ret == 0)
> + ret = be_stream_wait_io(evtchnl);
> +
> + /*
> + * Do this regardless of communication status with the backend:
> + * if we cannot remove remote resources remove what we can locally.
> + */
> + if (!be_alloc)
> + dbuf_free(&front_info->dbuf_list, dbuf_cookie);
> +
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + return ret;
> +}
> +
> +int xen_drm_front_fb_attach(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint64_t fb_cookie, uint32_t width,
> + uint32_t height, uint32_t pixel_format)
> +{
> + struct xen_drm_front_evtchnl *evtchnl;
> + struct xen_drm_front_dbuf *buf;
> + struct xendispl_req *req;
> + unsigned long flags;
> + int ret;
> +
> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
> + if (unlikely(!evtchnl))
> + return -EIO;
> +
> + buf = dbuf_get(&front_info->dbuf_list, dbuf_cookie);
> + if (!buf)
> + return -EINVAL;
> +
> + buf->fb_cookie = fb_cookie;
> +
> + mutex_lock(&evtchnl->u.req.req_io_lock);
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + req = be_prepare_req(evtchnl, XENDISPL_OP_FB_ATTACH);
> + req->op.fb_attach.dbuf_cookie = dbuf_cookie;
> + req->op.fb_attach.fb_cookie = fb_cookie;
> + req->op.fb_attach.width = width;
> + req->op.fb_attach.height = height;
> + req->op.fb_attach.pixel_format = pixel_format;
> +
> + ret = be_stream_do_io(evtchnl, req);
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> + if (ret == 0)
> + ret = be_stream_wait_io(evtchnl);
> +
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + return ret;
> +}
> +
> +int xen_drm_front_fb_detach(struct xen_drm_front_info *front_info,
> + uint64_t fb_cookie)
> +{
> + struct xen_drm_front_evtchnl *evtchnl;
> + struct xendispl_req *req;
> + unsigned long flags;
> + int ret;
> +
> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
> + if (unlikely(!evtchnl))
> + return -EIO;
> +
> + mutex_lock(&evtchnl->u.req.req_io_lock);
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + req = be_prepare_req(evtchnl, XENDISPL_OP_FB_DETACH);
> + req->op.fb_detach.fb_cookie = fb_cookie;
> +
> + ret = be_stream_do_io(evtchnl, req);
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> + if (ret == 0)
> + ret = be_stream_wait_io(evtchnl);
> +
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + return ret;
> +}
> +
> +int xen_drm_front_page_flip(struct xen_drm_front_info *front_info,
> + int conn_idx, uint64_t fb_cookie)
> +{
> + struct xen_drm_front_evtchnl *evtchnl;
> + struct xendispl_req *req;
> + unsigned long flags;
> + int ret;
> +
> + if (unlikely(conn_idx >= front_info->num_evt_pairs))
> + return -EINVAL;
> +
> + dbuf_flush_fb(&front_info->dbuf_list, fb_cookie);
> + evtchnl = &front_info->evt_pairs[conn_idx].req;
> +
> + mutex_lock(&evtchnl->u.req.req_io_lock);
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + req = be_prepare_req(evtchnl, XENDISPL_OP_PG_FLIP);
> + req->op.pg_flip.fb_cookie = fb_cookie;
> +
> + ret = be_stream_do_io(evtchnl, req);
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> + if (ret == 0)
> + ret = be_stream_wait_io(evtchnl);
> +
> + mutex_unlock(&evtchnl->u.req.req_io_lock);
> + return ret;
> +}
> +
> +void xen_drm_front_on_frame_done(struct xen_drm_front_info *front_info,
> + int conn_idx, uint64_t fb_cookie)
> +{
> + struct xen_drm_front_drm_info *drm_info = front_info->drm_info;
> +
> + if (unlikely(conn_idx >= front_info->cfg.num_connectors))
> + return;
> +
> + xen_drm_front_kms_on_frame_done(&drm_info->pipeline[conn_idx],
> + fb_cookie);
> +}
> +
> +static int xen_drm_drv_dumb_create(struct drm_file *filp,
> + struct drm_device *dev, struct drm_mode_create_dumb *args)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + struct drm_gem_object *obj;
> + int ret;
> +
> + /*
> + * Dumb creation is a two stage process: first we create a fully
> + * constructed GEM object which is communicated to the backend, and
> + * only after that we can create GEM's handle. This is done so,
> + * because of the possible races: once you create a handle it becomes
> + * immediately visible to user-space, so the latter can try accessing
> + * object without pages etc.
> + * For details also see drm_gem_handle_create
> + */
> + args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
> + args->size = args->pitch * args->height;
> +
> + obj = xen_drm_front_gem_create(dev, args->size);
> + if (IS_ERR_OR_NULL(obj)) {
> + ret = PTR_ERR(obj);
> + goto fail;
> + }
> +
> + /*
> + * In case of CONFIG_DRM_XEN_FRONTEND_CMA gem_obj is constructed
> + * via DRM CMA helpers and doesn't have ->pages allocated
> + * (xendrm_gem_get_pages will return NULL), but instead can provide
> + * sg table
> + */
> + if (xen_drm_front_gem_get_pages(obj))
> + ret = xen_drm_front_dbuf_create_from_pages(
> + drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(obj),
> + args->width, args->height, args->bpp,
> + args->size,
> + xen_drm_front_gem_get_pages(obj));
> + else
> + ret = xen_drm_front_dbuf_create_from_sgt(
> + drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(obj),
> + args->width, args->height, args->bpp,
> + args->size,
> + xen_drm_front_gem_get_sg_table(obj));
> + if (ret)
> + goto fail_backend;
> +
> + /* This is the tail of GEM object creation */
> + ret = drm_gem_handle_create(filp, obj, &args->handle);
> + if (ret)
> + goto fail_handle;
> +
> + /* Drop reference from allocate - handle holds it now */
> + drm_gem_object_put_unlocked(obj);
> + return 0;
> +
> +fail_handle:
> + xen_drm_front_dbuf_destroy(drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(obj));
> +fail_backend:
> + /* drop reference from allocate */
> + drm_gem_object_put_unlocked(obj);
> +fail:
> + DRM_ERROR("Failed to create dumb buffer: %d\n", ret);
> + return ret;
> +}
> +
> +static void xen_drm_drv_free_object_unlocked(struct drm_gem_object *obj)
> +{
> + struct xen_drm_front_drm_info *drm_info = obj->dev->dev_private;
> + int idx;
> +
> + if (drm_dev_enter(obj->dev, &idx)) {
> + xen_drm_front_dbuf_destroy(drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(obj));
> + drm_dev_exit(idx);
> + } else
> + dbuf_free(&drm_info->front_info->dbuf_list,
> + xen_drm_front_dbuf_to_cookie(obj));
> +
> + xen_drm_front_gem_free_object_unlocked(obj);
> +}
> +
> +static void xen_drm_drv_release(struct drm_device *dev)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + struct xen_drm_front_info *front_info = drm_info->front_info;
> +
> + xen_drm_front_kms_fini(drm_info);
> +
> + drm_atomic_helper_shutdown(dev);
> + drm_mode_config_cleanup(dev);
> +
> + drm_dev_fini(dev);
> + kfree(dev);
> +
> + if (front_info->cfg.be_alloc)
> + xenbus_switch_state(front_info->xb_dev,
> + XenbusStateInitialising);
> +
> + kfree(drm_info);
> +}
> +
> +static const struct file_operations xen_drm_dev_fops = {
> + .owner = THIS_MODULE,
> + .open = drm_open,
> + .release = drm_release,
> + .unlocked_ioctl = drm_ioctl,
> +#ifdef CONFIG_COMPAT
> + .compat_ioctl = drm_compat_ioctl,
> +#endif
> + .poll = drm_poll,
> + .read = drm_read,
> + .llseek = no_llseek,
> +#ifdef CONFIG_DRM_XEN_FRONTEND_CMA
> + .mmap = drm_gem_cma_mmap,
> +#else
> + .mmap = xen_drm_front_gem_mmap,
> +#endif
> +};
> +
> +static const struct vm_operations_struct xen_drm_drv_vm_ops = {
> + .open = drm_gem_vm_open,
> + .close = drm_gem_vm_close,
> +};
> +
> +static struct drm_driver xen_drm_driver = {
> + .driver_features = DRIVER_GEM | DRIVER_MODESET |
> + DRIVER_PRIME | DRIVER_ATOMIC,
> + .release = xen_drm_drv_release,
> + .gem_vm_ops = &xen_drm_drv_vm_ops,
> + .gem_free_object_unlocked = xen_drm_drv_free_object_unlocked,
> + .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
> + .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
> + .gem_prime_import = drm_gem_prime_import,
> + .gem_prime_export = drm_gem_prime_export,
> + .gem_prime_import_sg_table = xen_drm_front_gem_import_sg_table,
> + .gem_prime_get_sg_table = xen_drm_front_gem_get_sg_table,
> + .dumb_create = xen_drm_drv_dumb_create,
> + .fops = &xen_drm_dev_fops,
> + .name = "xendrm-du",
> + .desc = "Xen PV DRM Display Unit",
> + .date = "20180221",
> + .major = 1,
> + .minor = 0,
> +
> +#ifdef CONFIG_DRM_XEN_FRONTEND_CMA
> + .gem_prime_vmap = drm_gem_cma_prime_vmap,
> + .gem_prime_vunmap = drm_gem_cma_prime_vunmap,
> + .gem_prime_mmap = drm_gem_cma_prime_mmap,
> +#else
> + .gem_prime_vmap = xen_drm_front_gem_prime_vmap,
> + .gem_prime_vunmap = xen_drm_front_gem_prime_vunmap,
> + .gem_prime_mmap = xen_drm_front_gem_prime_mmap,
> +#endif
> +};
> +
> +static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
> +{
> + struct device *dev = &front_info->xb_dev->dev;
> + struct xen_drm_front_drm_info *drm_info;
> + struct drm_device *drm_dev;
> + int ret;
> +
> + DRM_INFO("Creating %s\n", xen_drm_driver.desc);
> +
> + drm_info = kzalloc(sizeof(*drm_info), GFP_KERNEL);
> + if (!drm_info) {
> + ret = -ENOMEM;
> + goto fail;
> + }
> +
> + drm_info->front_info = front_info;
> + front_info->drm_info = drm_info;
> +
> + drm_dev = drm_dev_alloc(&xen_drm_driver, dev);
> + if (!drm_dev) {
> + ret = -ENOMEM;
> + goto fail;
> + }
> +
> + drm_info->drm_dev = drm_dev;
> +
> + drm_dev->dev_private = drm_info;
> +
> + ret = xen_drm_front_kms_init(drm_info);
> + if (ret) {
> + DRM_ERROR("Failed to initialize DRM/KMS, ret %d\n", ret);
> + goto fail_modeset;
> + }
> +
> + ret = drm_dev_register(drm_dev, 0);
> + if (ret)
> + goto fail_register;
> +
> + DRM_INFO("Initialized %s %d.%d.%d %s on minor %d\n",
> + xen_drm_driver.name, xen_drm_driver.major,
> + xen_drm_driver.minor, xen_drm_driver.patchlevel,
> + xen_drm_driver.date, drm_dev->primary->index);
> +
> + return 0;
> +
> +fail_register:
> + drm_dev_unregister(drm_dev);
> +fail_modeset:
> + drm_kms_helper_poll_fini(drm_dev);
> + drm_mode_config_cleanup(drm_dev);
> +fail:
> + kfree(drm_info);
> + return ret;
> +}
> +
> +static void xen_drm_drv_fini(struct xen_drm_front_info *front_info)
> +{
> + struct xen_drm_front_drm_info *drm_info = front_info->drm_info;
> + struct drm_device *dev;
> +
> + if (!drm_info)
> + return;
> +
> + dev = drm_info->drm_dev;
> + if (!dev)
> + return;
> +
> + /* Nothing to do if device is already unplugged */
> + if (drm_dev_is_unplugged(dev))
> + return;
> +
> + drm_kms_helper_poll_fini(dev);
> + drm_dev_unplug(dev);
> +
> + front_info->drm_info = NULL;
> +
> + xen_drm_front_evtchnl_free_all(front_info);
> + dbuf_free_all(&front_info->dbuf_list);
> +
> + /*
> + * If we are not using backend allocated buffers, then tell the
> + * backend we are ready to (re)initialize. Otherwise, wait for
> + * drm_driver.release.
> + */
> + if (!front_info->cfg.be_alloc)
> + xenbus_switch_state(front_info->xb_dev,
> + XenbusStateInitialising);
> +}
> +
> +static int displback_initwait(struct xen_drm_front_info *front_info)
> +{
> + struct xen_drm_front_cfg *cfg = &front_info->cfg;
> + int ret;
> +
> + cfg->front_info = front_info;
> + ret = xen_drm_front_cfg_card(front_info, cfg);
> + if (ret < 0)
> + return ret;
> +
> + DRM_INFO("Have %d conector(s)\n", cfg->num_connectors);
> + /* Create event channels for all connectors and publish */
> + ret = xen_drm_front_evtchnl_create_all(front_info);
> + if (ret < 0)
> + return ret;
> +
> + return xen_drm_front_evtchnl_publish_all(front_info);
> +}
> +
> +static int displback_connect(struct xen_drm_front_info *front_info)
> +{
> + xen_drm_front_evtchnl_set_state(front_info, EVTCHNL_STATE_CONNECTED);
> + return xen_drm_drv_init(front_info);
> +}
> +
> +static void displback_disconnect(struct xen_drm_front_info *front_info)
> +{
> + if (!front_info->drm_info)
> + return;
> +
> + /* Tell the backend to wait until we release the DRM driver. */
> + xenbus_switch_state(front_info->xb_dev, XenbusStateReconfiguring);
> +
> + xen_drm_drv_fini(front_info);
> +}
> +
> +static void displback_changed(struct xenbus_device *xb_dev,
> + enum xenbus_state backend_state)
> +{
> + struct xen_drm_front_info *front_info = dev_get_drvdata(&xb_dev->dev);
> + int ret;
> +
> + DRM_DEBUG("Backend state is %s, front is %s\n",
> + xenbus_strstate(backend_state),
> + xenbus_strstate(xb_dev->state));
> +
> + switch (backend_state) {
> + case XenbusStateReconfiguring:
> + /* fall through */
> + case XenbusStateReconfigured:
> + /* fall through */
> + case XenbusStateInitialised:
> + break;
> +
> + case XenbusStateInitialising:
> + if (xb_dev->state == XenbusStateReconfiguring)
> + break;
> +
> + /* recovering after backend unexpected closure */
> + displback_disconnect(front_info);
> + break;
> +
> + case XenbusStateInitWait:
> + if (xb_dev->state == XenbusStateReconfiguring)
> + break;
> +
> + /* recovering after backend unexpected closure */
> + displback_disconnect(front_info);
> + if (xb_dev->state != XenbusStateInitialising)
> + break;
> +
> + ret = displback_initwait(front_info);
> + if (ret < 0)
> + xenbus_dev_fatal(xb_dev, ret,
> + "initializing frontend");
> + else
> + xenbus_switch_state(xb_dev, XenbusStateInitialised);
> + break;
> +
> + case XenbusStateConnected:
> + if (xb_dev->state != XenbusStateInitialised)
> + break;
> +
> + ret = displback_connect(front_info);
> + if (ret < 0) {
> + displback_disconnect(front_info);
> + xenbus_dev_fatal(xb_dev, ret,
> + "initializing DRM driver");
> + } else
> + xenbus_switch_state(xb_dev, XenbusStateConnected);
> + break;
> +
> + case XenbusStateClosing:
> + /*
> + * in this state backend starts freeing resources,
> + * so let it go into closed state, so we can also
> + * remove ours
> + */
> + break;
> +
> + case XenbusStateUnknown:
> + /* fall through */
> + case XenbusStateClosed:
> + if (xb_dev->state == XenbusStateClosed)
> + break;
> +
> + displback_disconnect(front_info);
> + break;
> + }
> +}
> +
> +static int xen_drv_probe(struct xenbus_device *xb_dev,
> + const struct xenbus_device_id *id)
> +{
> + struct xen_drm_front_info *front_info;
> + struct device *dev = &xb_dev->dev;
> + int ret;
> +
> + /*
> + * The device is not spawn from a device tree, so arch_setup_dma_ops
> + * is not called, thus leaving the device with dummy DMA ops.
> + * This makes the device return error on PRIME buffer import, which
> + * is not correct: to fix this call of_dma_configure() with a NULL
> + * node to set default DMA ops.
> + */
> + dev->bus->force_dma = true;
> + dev->coherent_dma_mask = DMA_BIT_MASK(32);
> + ret = of_dma_configure(dev, NULL);
> + if (ret < 0) {
> + DRM_ERROR("Cannot setup DMA ops, ret %d", ret);
> + return ret;
> + }
> +
> + front_info = devm_kzalloc(&xb_dev->dev,
> + sizeof(*front_info), GFP_KERNEL);
> + if (!front_info)
> + return -ENOMEM;
> +
> + front_info->xb_dev = xb_dev;
> + spin_lock_init(&front_info->io_lock);
> + INIT_LIST_HEAD(&front_info->dbuf_list);
> + dev_set_drvdata(&xb_dev->dev, front_info);
> +
> + return xenbus_switch_state(xb_dev, XenbusStateInitialising);
> +}
> +
> +static int xen_drv_remove(struct xenbus_device *dev)
> +{
> + struct xen_drm_front_info *front_info = dev_get_drvdata(&dev->dev);
> + int to = 100;
> +
> + xenbus_switch_state(dev, XenbusStateClosing);
> +
> + /*
> + * On driver removal it is disconnected from XenBus,
> + * so no backend state change events come via .otherend_changed
> + * callback. This prevents us from exiting gracefully, e.g.
> + * signaling the backend to free event channels, waiting for its
> + * state to change to XenbusStateClosed and cleaning at our end.
> + * Normally when front driver removed backend will finally go into
> + * XenbusStateInitWait state.
> + *
> + * Workaround: read backend's state manually and wait with time-out.
> + */
> + while ((xenbus_read_unsigned(front_info->xb_dev->otherend,
> + "state", XenbusStateUnknown) != XenbusStateInitWait) &&
> + to--)
> + msleep(10);
> +
> + if (!to)
> + DRM_ERROR("Backend state is %s while removing driver\n",
> + xenbus_strstate(xenbus_read_unsigned(
> + front_info->xb_dev->otherend,
> + "state", XenbusStateUnknown)));
> +
> + xen_drm_drv_fini(front_info);
> + xenbus_frontend_closed(dev);
> + return 0;
> +}
> +
> +static const struct xenbus_device_id xen_driver_ids[] = {
> + { XENDISPL_DRIVER_NAME },
> + { "" }
> +};
> +
> +static struct xenbus_driver xen_driver = {
> + .ids = xen_driver_ids,
> + .probe = xen_drv_probe,
> + .remove = xen_drv_remove,
> + .otherend_changed = displback_changed,
> +};
> +
> +static int __init xen_drv_init(void)
> +{
> + /* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */
> + if (XEN_PAGE_SIZE != PAGE_SIZE) {
> + DRM_ERROR(XENDISPL_DRIVER_NAME ": different kernel and Xen page sizes are not supported: XEN_PAGE_SIZE (%lu) != PAGE_SIZE (%lu)\n",
> + XEN_PAGE_SIZE, PAGE_SIZE);
> + return -ENODEV;
> + }
> +
> + if (!xen_domain())
> + return -ENODEV;
> +
> + if (!xen_has_pv_devices())
> + return -ENODEV;
> +
> + DRM_INFO("Registering XEN PV " XENDISPL_DRIVER_NAME "\n");
> + return xenbus_register_frontend(&xen_driver);
> +}
> +
> +static void __exit xen_drv_fini(void)
> +{
> + DRM_INFO("Unregistering XEN PV " XENDISPL_DRIVER_NAME "\n");
> + xenbus_unregister_driver(&xen_driver);
> +}
> +
> +module_init(xen_drv_init);
> +module_exit(xen_drv_fini);
> +
> +MODULE_DESCRIPTION("Xen para-virtualized display device frontend");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("xen:"XENDISPL_DRIVER_NAME);
> diff --git a/drivers/gpu/drm/xen/xen_drm_front.h b/drivers/gpu/drm/xen/xen_drm_front.h
> new file mode 100644
> index 000000000000..2d03de288f96
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front.h
> @@ -0,0 +1,189 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_H_
> +#define __XEN_DRM_FRONT_H_
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_simple_kms_helper.h>
> +
> +#include <linux/scatterlist.h>
> +
> +#include "xen_drm_front_cfg.h"
> +
> +/**
> + * DOC: Driver modes of operation in terms of display buffers used
> + *
> + * Depending on the requirements for the para-virtualized environment, namely
> + * requirements dictated by the accompanying DRM/(v)GPU drivers running in both
> + * host and guest environments, number of operating modes of para-virtualized
> + * display driver are supported:
> + *
> + * - display buffers can be allocated by either frontend driver or backend
> + * - display buffers can be allocated to be contiguous in memory or not
> + *
> + * Note! Frontend driver itself has no dependency on contiguous memory for
> + * its operation.
> + */
> +
> +/**
> + * DOC: Buffers allocated by the frontend driver
> + *
> + * The below modes of operation are configured at compile-time via
> + * frontend driver's kernel configuration:
> + */
> +
> +/**
> + * DOC: With GEM CMA helpers
> + *
> + * This use-case is useful when used with accompanying DRM/vGPU driver in
> + * guest domain which was designed to only work with contiguous buffers,
> + * e.g. DRM driver based on GEM CMA helpers: such drivers can only import
> + * contiguous PRIME buffers, thus requiring frontend driver to provide
> + * such. In order to implement this mode of operation para-virtualized
> + * frontend driver can be configured to use GEM CMA helpers.
> + */
> +
> +/**
> + * DOC: Without GEM CMA helpers
> + *
> + * If accompanying drivers can cope with non-contiguous memory then, to
> + * lower pressure on CMA subsystem of the kernel, driver can allocate
> + * buffers from system memory.
> + *
> + * Note! If used with accompanying DRM/(v)GPU drivers this mode of operation
> + * may require IOMMU support on the platform, so accompanying DRM/vGPU
> + * hardware can still reach display buffer memory while importing PRIME
> + * buffers from the frontend driver.
> + */
> +
> +/**
> + * DOC: Buffers allocated by the backend
> + *
> + * This mode of operation is run-time configured via guest domain configuration
> + * through XenStore entries.
> + *
> + * For systems which do not provide IOMMU support, but having specific
> + * requirements for display buffers it is possible to allocate such buffers
> + * at backend side and share those with the frontend.
> + * For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting
> + * physically contiguous memory, this allows implementing zero-copying
> + * use-cases.
> + *
> + * Note, while using this scenario the following should be considered:
> + *
> + * #. If guest domain dies then pages/grants received from the backend
> + * cannot be claimed back
> + *
> + * #. Misbehaving guest may send too many requests to the
> + * backend exhausting its grant references and memory
> + * (consider this from security POV)
> + */
> +
> +/**
> + * DOC: Driver limitations
> + *
> + * #. Only primary plane without additional properties is supported.
> + *
> + * #. Only one video mode per connector supported which is configured via XenStore.
> + *
> + * #. All CRTCs operate at fixed frequency of 60Hz.
> + */
> +
> +/* timeout in ms to wait for backend to respond */
> +#define XEN_DRM_FRONT_WAIT_BACK_MS 3000
> +
> +#ifndef GRANT_INVALID_REF
> +/*
> + * Note on usage of grant reference 0 as invalid grant reference:
> + * grant reference 0 is valid, but never exposed to a PV driver,
> + * because of the fact it is already in use/reserved by the PV console.
> + */
> +#define GRANT_INVALID_REF 0
> +#endif
> +
> +struct xen_drm_front_info {
> + struct xenbus_device *xb_dev;
> + struct xen_drm_front_drm_info *drm_info;
> +
> + /* to protect data between backend IO code and interrupt handler */
> + spinlock_t io_lock;
> +
> + int num_evt_pairs;
> + struct xen_drm_front_evtchnl_pair *evt_pairs;
> + struct xen_drm_front_cfg cfg;
> +
> + /* display buffers */
> + struct list_head dbuf_list;
> +};
> +
> +struct xen_drm_front_drm_pipeline {
> + struct xen_drm_front_drm_info *drm_info;
> +
> + int index;
> +
> + struct drm_simple_display_pipe pipe;
> +
> + struct drm_connector conn;
> + /* These are only for connector mode checking */
> + int width, height;
> +
> + struct drm_pending_vblank_event *pending_event;
> +
> + struct delayed_work pflip_to_worker;
> +
> + bool conn_connected;
> +};
> +
> +struct xen_drm_front_drm_info {
> + struct xen_drm_front_info *front_info;
> + struct drm_device *drm_dev;
> +
> + struct xen_drm_front_drm_pipeline pipeline[XEN_DRM_FRONT_MAX_CRTCS];
> +};
> +
> +static inline uint64_t xen_drm_front_fb_to_cookie(
> + struct drm_framebuffer *fb)
> +{
> + return (uint64_t)fb;
> +}
> +
> +static inline uint64_t xen_drm_front_dbuf_to_cookie(
> + struct drm_gem_object *gem_obj)
> +{
> + return (uint64_t)gem_obj;
> +}
> +
> +int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,
> + uint32_t x, uint32_t y, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t fb_cookie);
> +
> +int xen_drm_front_dbuf_create_from_sgt(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t size, struct sg_table *sgt);
> +
> +int xen_drm_front_dbuf_create_from_pages(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint32_t width, uint32_t height,
> + uint32_t bpp, uint64_t size, struct page **pages);
> +
> +int xen_drm_front_fb_attach(struct xen_drm_front_info *front_info,
> + uint64_t dbuf_cookie, uint64_t fb_cookie, uint32_t width,
> + uint32_t height, uint32_t pixel_format);
> +
> +int xen_drm_front_fb_detach(struct xen_drm_front_info *front_info,
> + uint64_t fb_cookie);
> +
> +int xen_drm_front_page_flip(struct xen_drm_front_info *front_info,
> + int conn_idx, uint64_t fb_cookie);
> +
> +void xen_drm_front_on_frame_done(struct xen_drm_front_info *front_info,
> + int conn_idx, uint64_t fb_cookie);
> +
> +#endif /* __XEN_DRM_FRONT_H_ */
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_cfg.c b/drivers/gpu/drm/xen/xen_drm_front_cfg.c
> new file mode 100644
> index 000000000000..9a0b2b8e6169
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_cfg.c
> @@ -0,0 +1,77 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include <drm/drmP.h>
> +
> +#include <linux/device.h>
> +
> +#include <xen/interface/io/displif.h>
> +#include <xen/xenbus.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_cfg.h"
> +
> +static int cfg_connector(struct xen_drm_front_info *front_info,
> + struct xen_drm_front_cfg_connector *connector,
> + const char *path, int index)
> +{
> + char *connector_path;
> +
> + connector_path = devm_kasprintf(&front_info->xb_dev->dev,
> + GFP_KERNEL, "%s/%d", path, index);
> + if (!connector_path)
> + return -ENOMEM;
> +
> + if (xenbus_scanf(XBT_NIL, connector_path, XENDISPL_FIELD_RESOLUTION,
> + "%d" XENDISPL_RESOLUTION_SEPARATOR "%d",
> + &connector->width, &connector->height) < 0) {
> + /* either no entry configured or wrong resolution set */
> + connector->width = 0;
> + connector->height = 0;
> + return -EINVAL;
> + }
> +
> + connector->xenstore_path = connector_path;
> +
> + DRM_INFO("Connector %s: resolution %dx%d\n",
> + connector_path, connector->width, connector->height);
> + return 0;
> +}
> +
> +int xen_drm_front_cfg_card(struct xen_drm_front_info *front_info,
> + struct xen_drm_front_cfg *cfg)
> +{
> + struct xenbus_device *xb_dev = front_info->xb_dev;
> + int ret, i;
> +
> + if (xenbus_read_unsigned(front_info->xb_dev->nodename,
> + XENDISPL_FIELD_BE_ALLOC, 0)) {
> + DRM_INFO("Backend can provide display buffers\n");
> + cfg->be_alloc = true;
> + }
> +
> + cfg->num_connectors = 0;
> + for (i = 0; i < ARRAY_SIZE(cfg->connectors); i++) {
> + ret = cfg_connector(front_info,
> + &cfg->connectors[i], xb_dev->nodename, i);
> + if (ret < 0)
> + break;
> + cfg->num_connectors++;
> + }
> +
> + if (!cfg->num_connectors) {
> + DRM_ERROR("No connector(s) configured at %s\n",
> + xb_dev->nodename);
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_cfg.h b/drivers/gpu/drm/xen/xen_drm_front_cfg.h
> new file mode 100644
> index 000000000000..6e7af670f8cd
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_cfg.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_CFG_H_
> +#define __XEN_DRM_FRONT_CFG_H_
> +
> +#include <linux/types.h>
> +
> +#define XEN_DRM_FRONT_MAX_CRTCS 4
> +
> +struct xen_drm_front_cfg_connector {
> + int width;
> + int height;
> + char *xenstore_path;
> +};
> +
> +struct xen_drm_front_cfg {
> + struct xen_drm_front_info *front_info;
> + /* number of connectors in this configuration */
> + int num_connectors;
> + /* connector configurations */
> + struct xen_drm_front_cfg_connector connectors[XEN_DRM_FRONT_MAX_CRTCS];
> + /* set if dumb buffers are allocated externally on backend side */
> + bool be_alloc;
> +};
> +
> +int xen_drm_front_cfg_card(struct xen_drm_front_info *front_info,
> + struct xen_drm_front_cfg *cfg);
> +
> +#endif /* __XEN_DRM_FRONT_CFG_H_ */
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_conn.c b/drivers/gpu/drm/xen/xen_drm_front_conn.c
> new file mode 100644
> index 000000000000..b5d0b27983b8
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_conn.c
> @@ -0,0 +1,115 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +
> +#include <video/videomode.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_conn.h"
> +#include "xen_drm_front_kms.h"
> +
> +static struct xen_drm_front_drm_pipeline *
> +to_xen_drm_pipeline(struct drm_connector *connector)
> +{
> + return container_of(connector, struct xen_drm_front_drm_pipeline, conn);
> +}
> +
> +static const uint32_t plane_formats[] = {
> + DRM_FORMAT_RGB565,
> + DRM_FORMAT_RGB888,
> + DRM_FORMAT_XRGB8888,
> + DRM_FORMAT_ARGB8888,
> + DRM_FORMAT_XRGB4444,
> + DRM_FORMAT_ARGB4444,
> + DRM_FORMAT_XRGB1555,
> + DRM_FORMAT_ARGB1555,
> +};
> +
> +const uint32_t *xen_drm_front_conn_get_formats(int *format_count)
> +{
> + *format_count = ARRAY_SIZE(plane_formats);
> + return plane_formats;
> +}
> +
> +static int connector_detect(struct drm_connector *connector,
> + struct drm_modeset_acquire_ctx *ctx,
> + bool force)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(connector);
> +
> + if (drm_dev_is_unplugged(connector->dev))
> + pipeline->conn_connected = false;
> +
> + return pipeline->conn_connected ? connector_status_connected :
> + connector_status_disconnected;
> +}
> +
> +#define XEN_DRM_CRTC_VREFRESH_HZ 60
> +
> +static int connector_get_modes(struct drm_connector *connector)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(connector);
> + struct drm_display_mode *mode;
> + struct videomode videomode;
> + int width, height;
> +
> + mode = drm_mode_create(connector->dev);
> + if (!mode)
> + return 0;
> +
> + memset(&videomode, 0, sizeof(videomode));
> + videomode.hactive = pipeline->width;
> + videomode.vactive = pipeline->height;
> + width = videomode.hactive + videomode.hfront_porch +
> + videomode.hback_porch + videomode.hsync_len;
> + height = videomode.vactive + videomode.vfront_porch +
> + videomode.vback_porch + videomode.vsync_len;
> + videomode.pixelclock = width * height * XEN_DRM_CRTC_VREFRESH_HZ;
> + mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
> +
> + drm_display_mode_from_videomode(&videomode, mode);
> + drm_mode_probed_add(connector, mode);
> + return 1;
> +}
> +
> +static const struct drm_connector_helper_funcs connector_helper_funcs = {
> + .get_modes = connector_get_modes,
> + .detect_ctx = connector_detect,
> +};
> +
> +static const struct drm_connector_funcs connector_funcs = {
> + .dpms = drm_helper_connector_dpms,
> + .fill_modes = drm_helper_probe_single_connector_modes,
> + .destroy = drm_connector_cleanup,
> + .reset = drm_atomic_helper_connector_reset,
> + .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> + .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +int xen_drm_front_conn_init(struct xen_drm_front_drm_info *drm_info,
> + struct drm_connector *connector)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(connector);
> +
> + drm_connector_helper_add(connector, &connector_helper_funcs);
> +
> + pipeline->conn_connected = true;
> +
> + connector->polled = DRM_CONNECTOR_POLL_CONNECT |
> + DRM_CONNECTOR_POLL_DISCONNECT;
> +
> + return drm_connector_init(drm_info->drm_dev, connector,
> + &connector_funcs, DRM_MODE_CONNECTOR_VIRTUAL);
> +}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_conn.h b/drivers/gpu/drm/xen/xen_drm_front_conn.h
> new file mode 100644
> index 000000000000..f38c4b6db5df
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_conn.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_CONN_H_
> +#define __XEN_DRM_FRONT_CONN_H_
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_encoder.h>
> +
> +#include <linux/wait.h>
> +
> +struct xen_drm_front_drm_info;
> +
> +int xen_drm_front_conn_init(struct xen_drm_front_drm_info *drm_info,
> + struct drm_connector *connector);
> +
> +const uint32_t *xen_drm_front_conn_get_formats(int *format_count);
> +
> +#endif /* __XEN_DRM_FRONT_CONN_H_ */
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
> new file mode 100644
> index 000000000000..e521785fd22b
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
> @@ -0,0 +1,382 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include <drm/drmP.h>
> +
> +#include <linux/errno.h>
> +#include <linux/irq.h>
> +
> +#include <xen/xenbus.h>
> +#include <xen/events.h>
> +#include <xen/grant_table.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_evtchnl.h"
> +
> +static irqreturn_t evtchnl_interrupt_ctrl(int irq, void *dev_id)
> +{
> + struct xen_drm_front_evtchnl *evtchnl = dev_id;
> + struct xen_drm_front_info *front_info = evtchnl->front_info;
> + struct xendispl_resp *resp;
> + RING_IDX i, rp;
> + unsigned long flags;
> +
> + if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
> + return IRQ_HANDLED;
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> +
> +again:
> + rp = evtchnl->u.req.ring.sring->rsp_prod;
> + /* ensure we see queued responses up to rp */
> + virt_rmb();
> +
> + for (i = evtchnl->u.req.ring.rsp_cons; i != rp; i++) {
> + resp = RING_GET_RESPONSE(&evtchnl->u.req.ring, i);
> + if (unlikely(resp->id != evtchnl->evt_id))
> + continue;
> +
> + switch (resp->operation) {
> + case XENDISPL_OP_PG_FLIP:
> + case XENDISPL_OP_FB_ATTACH:
> + case XENDISPL_OP_FB_DETACH:
> + case XENDISPL_OP_DBUF_CREATE:
> + case XENDISPL_OP_DBUF_DESTROY:
> + case XENDISPL_OP_SET_CONFIG:
> + evtchnl->u.req.resp_status = resp->status;
> + complete(&evtchnl->u.req.completion);
> + break;
> +
> + default:
> + DRM_ERROR("Operation %d is not supported\n",
> + resp->operation);
> + break;
> + }
> + }
> +
> + evtchnl->u.req.ring.rsp_cons = i;
> +
> + if (i != evtchnl->u.req.ring.req_prod_pvt) {
> + int more_to_do;
> +
> + RING_FINAL_CHECK_FOR_RESPONSES(&evtchnl->u.req.ring,
> + more_to_do);
> + if (more_to_do)
> + goto again;
> + } else
> + evtchnl->u.req.ring.sring->rsp_event = i + 1;
> +
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id)
> +{
> + struct xen_drm_front_evtchnl *evtchnl = dev_id;
> + struct xen_drm_front_info *front_info = evtchnl->front_info;
> + struct xendispl_event_page *page = evtchnl->u.evt.page;
> + uint32_t cons, prod;
> + unsigned long flags;
> +
> + if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
> + return IRQ_HANDLED;
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> +
> + prod = page->in_prod;
> + /* ensure we see ring contents up to prod */
> + virt_rmb();
> + if (prod == page->in_cons)
> + goto out;
> +
> + for (cons = page->in_cons; cons != prod; cons++) {
> + struct xendispl_evt *event;
> +
> + event = &XENDISPL_IN_RING_REF(page, cons);
> + if (unlikely(event->id != evtchnl->evt_id++))
> + continue;
> +
> + switch (event->type) {
> + case XENDISPL_EVT_PG_FLIP:
> + xen_drm_front_on_frame_done(front_info, evtchnl->index,
> + event->op.pg_flip.fb_cookie);
> + break;
> + }
> + }
> + page->in_cons = cons;
> + /* ensure ring contents */
> + virt_wmb();
> +
> +out:
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> + return IRQ_HANDLED;
> +}
> +
> +static void evtchnl_free(struct xen_drm_front_info *front_info,
> + struct xen_drm_front_evtchnl *evtchnl)
> +{
> + unsigned long page = 0;
> +
> + if (evtchnl->type == EVTCHNL_TYPE_REQ)
> + page = (unsigned long)evtchnl->u.req.ring.sring;
> + else if (evtchnl->type == EVTCHNL_TYPE_EVT)
> + page = (unsigned long)evtchnl->u.evt.page;
> + if (!page)
> + return;
> +
> + evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
> +
> + if (evtchnl->type == EVTCHNL_TYPE_REQ) {
> + /* release all who still waits for response if any */
> + evtchnl->u.req.resp_status = -EIO;
> + complete_all(&evtchnl->u.req.completion);
> + }
> +
> + if (evtchnl->irq)
> + unbind_from_irqhandler(evtchnl->irq, evtchnl);
> +
> + if (evtchnl->port)
> + xenbus_free_evtchn(front_info->xb_dev, evtchnl->port);
> +
> + /* end access and free the page */
> + if (evtchnl->gref != GRANT_INVALID_REF)
> + gnttab_end_foreign_access(evtchnl->gref, 0, page);
> +
> + memset(evtchnl, 0, sizeof(*evtchnl));
> +}
> +
> +static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index,
> + struct xen_drm_front_evtchnl *evtchnl,
> + enum xen_drm_front_evtchnl_type type)
> +{
> + struct xenbus_device *xb_dev = front_info->xb_dev;
> + unsigned long page;
> + grant_ref_t gref;
> + irq_handler_t handler;
> + int ret;
> +
> + memset(evtchnl, 0, sizeof(*evtchnl));
> + evtchnl->type = type;
> + evtchnl->index = index;
> + evtchnl->front_info = front_info;
> + evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
> + evtchnl->gref = GRANT_INVALID_REF;
> +
> + page = get_zeroed_page(GFP_NOIO | __GFP_HIGH);
> + if (!page) {
> + ret = -ENOMEM;
> + goto fail;
> + }
> +
> + if (type == EVTCHNL_TYPE_REQ) {
> + struct xen_displif_sring *sring;
> +
> + init_completion(&evtchnl->u.req.completion);
> + mutex_init(&evtchnl->u.req.req_io_lock);
> + sring = (struct xen_displif_sring *)page;
> + SHARED_RING_INIT(sring);
> + FRONT_RING_INIT(&evtchnl->u.req.ring,
> + sring, XEN_PAGE_SIZE);
> +
> + ret = xenbus_grant_ring(xb_dev, sring, 1, &gref);
> + if (ret < 0)
> + goto fail;
> +
> + handler = evtchnl_interrupt_ctrl;
> + } else {
> + evtchnl->u.evt.page = (struct xendispl_event_page *)page;
> +
> + ret = gnttab_grant_foreign_access(xb_dev->otherend_id,
> + virt_to_gfn((void *)page), 0);
> + if (ret < 0)
> + goto fail;
> +
> + gref = ret;
> + handler = evtchnl_interrupt_evt;
> + }
> + evtchnl->gref = gref;
> +
> + ret = xenbus_alloc_evtchn(xb_dev, &evtchnl->port);
> + if (ret < 0)
> + goto fail;
> +
> + ret = bind_evtchn_to_irqhandler(evtchnl->port,
> + handler, 0, xb_dev->devicetype, evtchnl);
> + if (ret < 0)
> + goto fail;
> +
> + evtchnl->irq = ret;
> + return 0;
> +
> +fail:
> + DRM_ERROR("Failed to allocate ring: %d\n", ret);
> + return ret;
> +}
> +
> +int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info)
> +{
> + struct xen_drm_front_cfg *cfg;
> + int ret, conn;
> +
> + cfg = &front_info->cfg;
> +
> + front_info->evt_pairs = kcalloc(cfg->num_connectors,
> + sizeof(struct xen_drm_front_evtchnl_pair), GFP_KERNEL);
> + if (!front_info->evt_pairs) {
> + ret = -ENOMEM;
> + goto fail;
> + }
> +
> + for (conn = 0; conn < cfg->num_connectors; conn++) {
> + ret = evtchnl_alloc(front_info, conn,
> + &front_info->evt_pairs[conn].req,
> + EVTCHNL_TYPE_REQ);
> + if (ret < 0) {
> + DRM_ERROR("Error allocating control channel\n");
> + goto fail;
> + }
> +
> + ret = evtchnl_alloc(front_info, conn,
> + &front_info->evt_pairs[conn].evt,
> + EVTCHNL_TYPE_EVT);
> + if (ret < 0) {
> + DRM_ERROR("Error allocating in-event channel\n");
> + goto fail;
> + }
> + }
> + front_info->num_evt_pairs = cfg->num_connectors;
> + return 0;
> +
> +fail:
> + xen_drm_front_evtchnl_free_all(front_info);
> + return ret;
> +}
> +
> +static int evtchnl_publish(struct xenbus_transaction xbt,
> + struct xen_drm_front_evtchnl *evtchnl, const char *path,
> + const char *node_ring, const char *node_chnl)
> +{
> + struct xenbus_device *xb_dev = evtchnl->front_info->xb_dev;
> + int ret;
> +
> + /* write control channel ring reference */
> + ret = xenbus_printf(xbt, path, node_ring, "%u", evtchnl->gref);
> + if (ret < 0) {
> + xenbus_dev_error(xb_dev, ret, "writing ring-ref");
> + return ret;
> + }
> +
> + /* write event channel ring reference */
> + ret = xenbus_printf(xbt, path, node_chnl, "%u", evtchnl->port);
> + if (ret < 0) {
> + xenbus_dev_error(xb_dev, ret, "writing event channel");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info)
> +{
> + struct xenbus_transaction xbt;
> + struct xen_drm_front_cfg *plat_data;
> + int ret, conn;
> +
> + plat_data = &front_info->cfg;
> +
> +again:
> + ret = xenbus_transaction_start(&xbt);
> + if (ret < 0) {
> + xenbus_dev_fatal(front_info->xb_dev, ret,
> + "starting transaction");
> + return ret;
> + }
> +
> + for (conn = 0; conn < plat_data->num_connectors; conn++) {
> + ret = evtchnl_publish(xbt,
> + &front_info->evt_pairs[conn].req,
> + plat_data->connectors[conn].xenstore_path,
> + XENDISPL_FIELD_REQ_RING_REF,
> + XENDISPL_FIELD_REQ_CHANNEL);
> + if (ret < 0)
> + goto fail;
> +
> + ret = evtchnl_publish(xbt,
> + &front_info->evt_pairs[conn].evt,
> + plat_data->connectors[conn].xenstore_path,
> + XENDISPL_FIELD_EVT_RING_REF,
> + XENDISPL_FIELD_EVT_CHANNEL);
> + if (ret < 0)
> + goto fail;
> + }
> +
> + ret = xenbus_transaction_end(xbt, 0);
> + if (ret < 0) {
> + if (ret == -EAGAIN)
> + goto again;
> +
> + xenbus_dev_fatal(front_info->xb_dev, ret,
> + "completing transaction");
> + goto fail_to_end;
> + }
> +
> + return 0;
> +
> +fail:
> + xenbus_transaction_end(xbt, 1);
> +
> +fail_to_end:
> + xenbus_dev_fatal(front_info->xb_dev, ret, "writing Xen store");
> + return ret;
> +}
> +
> +void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl)
> +{
> + int notify;
> +
> + evtchnl->u.req.ring.req_prod_pvt++;
> + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&evtchnl->u.req.ring, notify);
> + if (notify)
> + notify_remote_via_irq(evtchnl->irq);
> +}
> +
> +void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info,
> + enum xen_drm_front_evtchnl_state state)
> +{
> + unsigned long flags;
> + int i;
> +
> + if (!front_info->evt_pairs)
> + return;
> +
> + spin_lock_irqsave(&front_info->io_lock, flags);
> + for (i = 0; i < front_info->num_evt_pairs; i++) {
> + front_info->evt_pairs[i].req.state = state;
> + front_info->evt_pairs[i].evt.state = state;
> + }
> + spin_unlock_irqrestore(&front_info->io_lock, flags);
> +
> +}
> +
> +void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info)
> +{
> + int i;
> +
> + if (!front_info->evt_pairs)
> + return;
> +
> + for (i = 0; i < front_info->num_evt_pairs; i++) {
> + evtchnl_free(front_info, &front_info->evt_pairs[i].req);
> + evtchnl_free(front_info, &front_info->evt_pairs[i].evt);
> + }
> +
> + kfree(front_info->evt_pairs);
> + front_info->evt_pairs = NULL;
> +}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.h b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.h
> new file mode 100644
> index 000000000000..38ceacb8e9c1
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.h
> @@ -0,0 +1,81 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_EVTCHNL_H_
> +#define __XEN_DRM_FRONT_EVTCHNL_H_
> +
> +#include <linux/completion.h>
> +#include <linux/types.h>
> +
> +#include <xen/interface/io/ring.h>
> +#include <xen/interface/io/displif.h>
> +
> +/*
> + * All operations which are not connector oriented use this ctrl event channel,
> + * e.g. fb_attach/destroy which belong to a DRM device, not to a CRTC.
> + */
> +#define GENERIC_OP_EVT_CHNL 0
> +
> +enum xen_drm_front_evtchnl_state {
> + EVTCHNL_STATE_DISCONNECTED,
> + EVTCHNL_STATE_CONNECTED,
> +};
> +
> +enum xen_drm_front_evtchnl_type {
> + EVTCHNL_TYPE_REQ,
> + EVTCHNL_TYPE_EVT,
> +};
> +
> +struct xen_drm_front_drm_info;
> +
> +struct xen_drm_front_evtchnl {
> + struct xen_drm_front_info *front_info;
> + int gref;
> + int port;
> + int irq;
> + int index;
> + enum xen_drm_front_evtchnl_state state;
> + enum xen_drm_front_evtchnl_type type;
> + /* either response id or incoming event id */
> + uint16_t evt_id;
> + /* next request id or next expected event id */
> + uint16_t evt_next_id;
> + union {
> + struct {
> + struct xen_displif_front_ring ring;
> + struct completion completion;
> + /* latest response status */
> + int resp_status;
> + /* serializer for backend IO: request/response */
> + struct mutex req_io_lock;
> + } req;
> + struct {
> + struct xendispl_event_page *page;
> + } evt;
> + } u;
> +};
> +
> +struct xen_drm_front_evtchnl_pair {
> + struct xen_drm_front_evtchnl req;
> + struct xen_drm_front_evtchnl evt;
> +};
> +
> +int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info);
> +
> +int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info);
> +
> +void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl);
> +
> +void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info,
> + enum xen_drm_front_evtchnl_state state);
> +
> +void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info);
> +
> +#endif /* __XEN_DRM_FRONT_EVTCHNL_H_ */
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
> new file mode 100644
> index 000000000000..ad3c6fe4afa3
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
> @@ -0,0 +1,309 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include "xen_drm_front_gem.h"
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_fb_helper.h>
> +#include <drm/drm_gem.h>
> +
> +#include <linux/dma-buf.h>
> +#include <linux/scatterlist.h>
> +#include <linux/shmem_fs.h>
> +
> +#include <xen/balloon.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_shbuf.h"
> +
> +struct xen_gem_object {
> + struct drm_gem_object base;
> +
> + size_t num_pages;
> + struct page **pages;
> +
> + /* set for buffers allocated by the backend */
> + bool be_alloc;
> +
> + /* this is for imported PRIME buffer */
> + struct sg_table *sgt_imported;
> +};
> +
> +static inline struct xen_gem_object *to_xen_gem_obj(
> + struct drm_gem_object *gem_obj)
> +{
> + return container_of(gem_obj, struct xen_gem_object, base);
> +}
> +
> +static int gem_alloc_pages_array(struct xen_gem_object *xen_obj,
> + size_t buf_size)
> +{
> + xen_obj->num_pages = DIV_ROUND_UP(buf_size, PAGE_SIZE);
> + xen_obj->pages = kvmalloc_array(xen_obj->num_pages,
> + sizeof(struct page *), GFP_KERNEL);
> + return xen_obj->pages == NULL ? -ENOMEM : 0;
> +}
> +
> +static void gem_free_pages_array(struct xen_gem_object *xen_obj)
> +{
> + kvfree(xen_obj->pages);
> + xen_obj->pages = NULL;
> +}
> +
> +static struct xen_gem_object *gem_create_obj(struct drm_device *dev,
> + size_t size)
> +{
> + struct xen_gem_object *xen_obj;
> + int ret;
> +
> + xen_obj = kzalloc(sizeof(*xen_obj), GFP_KERNEL);
> + if (!xen_obj)
> + return ERR_PTR(-ENOMEM);
> +
> + ret = drm_gem_object_init(dev, &xen_obj->base, size);
> + if (ret < 0) {
> + kfree(xen_obj);
> + return ERR_PTR(ret);
> + }
> +
> + return xen_obj;
> +}
> +
> +static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + struct xen_gem_object *xen_obj;
> + int ret;
> +
> + size = round_up(size, PAGE_SIZE);
> + xen_obj = gem_create_obj(dev, size);
> + if (IS_ERR_OR_NULL(xen_obj))
> + return xen_obj;
> +
> + if (drm_info->front_info->cfg.be_alloc) {
> + /*
> + * backend will allocate space for this buffer, so
> + * only allocate array of pointers to pages
> + */
> + ret = gem_alloc_pages_array(xen_obj, size);
> + if (ret < 0)
> + goto fail;
> +
> + /*
> + * allocate ballooned pages which will be used to map
> + * grant references provided by the backend
> + */
> + ret = alloc_xenballooned_pages(xen_obj->num_pages,
> + xen_obj->pages);
> + if (ret < 0) {
> + DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n",
> + xen_obj->num_pages, ret);
> + gem_free_pages_array(xen_obj);
> + goto fail;
> + }
> +
> + xen_obj->be_alloc = true;
> + return xen_obj;
> + }
> + /*
> + * need to allocate backing pages now, so we can share those
> + * with the backend
> + */
> + xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE);
> + xen_obj->pages = drm_gem_get_pages(&xen_obj->base);
> + if (IS_ERR_OR_NULL(xen_obj->pages)) {
> + ret = PTR_ERR(xen_obj->pages);
> + xen_obj->pages = NULL;
> + goto fail;
> + }
> +
> + return xen_obj;
> +
> +fail:
> + DRM_ERROR("Failed to allocate buffer with size %zu\n", size);
> + return ERR_PTR(ret);
> +}
> +
> +struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev,
> + size_t size)
> +{
> + struct xen_gem_object *xen_obj;
> +
> + xen_obj = gem_create(dev, size);
> + if (IS_ERR_OR_NULL(xen_obj))
> + return ERR_CAST(xen_obj);
> +
> + return &xen_obj->base;
> +}
> +
> +void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj)
> +{
> + struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
> +
> + if (xen_obj->base.import_attach) {
> + drm_prime_gem_destroy(&xen_obj->base, xen_obj->sgt_imported);
> + gem_free_pages_array(xen_obj);
> + } else {
> + if (xen_obj->pages) {
> + if (xen_obj->be_alloc) {
> + free_xenballooned_pages(xen_obj->num_pages,
> + xen_obj->pages);
> + gem_free_pages_array(xen_obj);
> + } else
> + drm_gem_put_pages(&xen_obj->base,
> + xen_obj->pages, true, false);
> + }
> + }
> + drm_gem_object_release(gem_obj);
> + kfree(xen_obj);
> +}
> +
> +struct page **xen_drm_front_gem_get_pages(struct drm_gem_object *gem_obj)
> +{
> + struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
> +
> + return xen_obj->pages;
> +}
> +
> +struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj)
> +{
> + struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
> +
> + if (!xen_obj->pages)
> + return NULL;
> +
> + return drm_prime_pages_to_sg(xen_obj->pages, xen_obj->num_pages);
> +}
> +
> +struct drm_gem_object *xen_drm_front_gem_import_sg_table(struct drm_device *dev,
> + struct dma_buf_attachment *attach, struct sg_table *sgt)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + struct xen_gem_object *xen_obj;
> + size_t size;
> + int ret;
> +
> + size = attach->dmabuf->size;
> + xen_obj = gem_create_obj(dev, size);
> + if (IS_ERR_OR_NULL(xen_obj))
> + return ERR_CAST(xen_obj);
> +
> + ret = gem_alloc_pages_array(xen_obj, size);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + xen_obj->sgt_imported = sgt;
> +
> + ret = drm_prime_sg_to_page_addr_arrays(sgt, xen_obj->pages,
> + NULL, xen_obj->num_pages);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + /*
> + * N.B. Although we have an API to create display buffer from sgt
> + * we use pages API, because we still need those for GEM handling,
> + * e.g. for mapping etc.
> + */
> + ret = xen_drm_front_dbuf_create_from_pages(drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(&xen_obj->base),
> + 0, 0, 0, size, xen_obj->pages);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + DRM_DEBUG("Imported buffer of size %zu with nents %u\n",
> + size, sgt->nents);
> +
> + return &xen_obj->base;
> +}
> +
> +static int gem_mmap_obj(struct xen_gem_object *xen_obj,
> + struct vm_area_struct *vma)
> +{
> + unsigned long addr = vma->vm_start;
> + int i;
> +
> + /*
> + * clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
> + * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
> + * the whole buffer.
> + */
> + vma->vm_flags &= ~VM_PFNMAP;
> + vma->vm_flags |= VM_MIXEDMAP;
> + vma->vm_pgoff = 0;
> + vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
> +
> + /*
> + * vm_operations_struct.fault handler will be called if CPU access
> + * to VM is here. For GPUs this isn't the case, because CPU
> + * doesn't touch the memory. Insert pages now, so both CPU and GPU are
> + * happy.
> + * FIXME: as we insert all the pages now then no .fault handler must
> + * be called, so don't provide one
> + */
> + for (i = 0; i < xen_obj->num_pages; i++) {
> + int ret;
> +
> + ret = vm_insert_page(vma, addr, xen_obj->pages[i]);
> + if (ret < 0) {
> + DRM_ERROR("Failed to insert pages into vma: %d\n", ret);
> + return ret;
> + }
> +
> + addr += PAGE_SIZE;
> + }
> + return 0;
> +}
> +
> +int xen_drm_front_gem_mmap(struct file *filp, struct vm_area_struct *vma)
> +{
> + struct xen_gem_object *xen_obj;
> + struct drm_gem_object *gem_obj;
> + int ret;
> +
> + ret = drm_gem_mmap(filp, vma);
> + if (ret < 0)
> + return ret;
> +
> + gem_obj = vma->vm_private_data;
> + xen_obj = to_xen_gem_obj(gem_obj);
> + return gem_mmap_obj(xen_obj, vma);
> +}
> +
> +void *xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj)
> +{
> + struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
> +
> + if (!xen_obj->pages)
> + return NULL;
> +
> + return vmap(xen_obj->pages, xen_obj->num_pages,
> + VM_MAP, pgprot_writecombine(PAGE_KERNEL));
> +}
> +
> +void xen_drm_front_gem_prime_vunmap(struct drm_gem_object *gem_obj,
> + void *vaddr)
> +{
> + vunmap(vaddr);
> +}
> +
> +int xen_drm_front_gem_prime_mmap(struct drm_gem_object *gem_obj,
> + struct vm_area_struct *vma)
> +{
> + struct xen_gem_object *xen_obj;
> + int ret;
> +
> + ret = drm_gem_mmap_obj(gem_obj, gem_obj->size, vma);
> + if (ret < 0)
> + return ret;
> +
> + xen_obj = to_xen_gem_obj(gem_obj);
> + return gem_mmap_obj(xen_obj, vma);
> +}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.h b/drivers/gpu/drm/xen/xen_drm_front_gem.h
> new file mode 100644
> index 000000000000..a94130a1d73e
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.h
> @@ -0,0 +1,41 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_GEM_H
> +#define __XEN_DRM_FRONT_GEM_H
> +
> +#include <drm/drmP.h>
> +
> +struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev,
> + size_t size);
> +
> +struct drm_gem_object *xen_drm_front_gem_import_sg_table(struct drm_device *dev,
> + struct dma_buf_attachment *attach, struct sg_table *sgt);
> +
> +struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj);
> +
> +struct page **xen_drm_front_gem_get_pages(struct drm_gem_object *obj);
> +
> +void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj);
> +
> +#ifndef CONFIG_DRM_XEN_FRONTEND_CMA
> +
> +int xen_drm_front_gem_mmap(struct file *filp, struct vm_area_struct *vma);
> +
> +void *xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj);
> +
> +void xen_drm_front_gem_prime_vunmap(struct drm_gem_object *gem_obj,
> + void *vaddr);
> +
> +int xen_drm_front_gem_prime_mmap(struct drm_gem_object *gem_obj,
> + struct vm_area_struct *vma);
> +#endif
> +
> +#endif /* __XEN_DRM_FRONT_GEM_H */
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem_cma.c b/drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
> new file mode 100644
> index 000000000000..e0ca1e113df9
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem_cma.c
> @@ -0,0 +1,78 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_gem.h>
> +#include <drm/drm_fb_cma_helper.h>
> +#include <drm/drm_gem_cma_helper.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_gem.h"
> +
> +struct drm_gem_object *xen_drm_front_gem_import_sg_table(struct drm_device *dev,
> + struct dma_buf_attachment *attach, struct sg_table *sgt)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + struct drm_gem_object *gem_obj;
> + struct drm_gem_cma_object *cma_obj;
> + int ret;
> +
> + gem_obj = drm_gem_cma_prime_import_sg_table(dev, attach, sgt);
> + if (IS_ERR_OR_NULL(gem_obj))
> + return gem_obj;
> +
> + cma_obj = to_drm_gem_cma_obj(gem_obj);
> +
> + ret = xen_drm_front_dbuf_create_from_sgt(
> + drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(gem_obj),
> + 0, 0, 0, gem_obj->size,
> + drm_gem_cma_prime_get_sg_table(gem_obj));
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + DRM_DEBUG("Imported CMA buffer of size %zu\n", gem_obj->size);
> +
> + return gem_obj;
> +}
> +
> +struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj)
> +{
> + return drm_gem_cma_prime_get_sg_table(gem_obj);
> +}
> +
> +struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev,
> + size_t size)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + struct drm_gem_cma_object *cma_obj;
> +
> + if (drm_info->front_info->cfg.be_alloc) {
> + /* This use-case is not yet supported and probably won't be */
> + DRM_ERROR("Backend allocated buffers and CMA helpers are not supported at the same time\n");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + cma_obj = drm_gem_cma_create(dev, size);
> + if (IS_ERR_OR_NULL(cma_obj))
> + return ERR_CAST(cma_obj);
> +
> + return &cma_obj->base;
> +}
> +
> +void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj)
> +{
> + drm_gem_cma_free_object(gem_obj);
> +}
> +
> +struct page **xen_drm_front_gem_get_pages(struct drm_gem_object *gem_obj)
> +{
> + return NULL;
> +}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_kms.c b/drivers/gpu/drm/xen/xen_drm_front_kms.c
> new file mode 100644
> index 000000000000..545049dfaf0a
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_kms.c
> @@ -0,0 +1,371 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include "xen_drm_front_kms.h"
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_atomic.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_gem.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_conn.h"
> +
> +/*
> + * Timeout in ms to wait for frame done event from the backend:
> + * must be a bit more than IO time-out
> + */
> +#define FRAME_DONE_TO_MS (XEN_DRM_FRONT_WAIT_BACK_MS + 100)
> +
> +static struct xen_drm_front_drm_pipeline *
> +to_xen_drm_pipeline(struct drm_simple_display_pipe *pipe)
> +{
> + return container_of(pipe, struct xen_drm_front_drm_pipeline, pipe);
> +}
> +
> +static void fb_destroy(struct drm_framebuffer *fb)
> +{
> + struct xen_drm_front_drm_info *drm_info = fb->dev->dev_private;
> + int idx;
> +
> + if (drm_dev_enter(fb->dev, &idx)) {
> + xen_drm_front_fb_detach(drm_info->front_info,
> + xen_drm_front_fb_to_cookie(fb));
> + drm_dev_exit(idx);
> + }
> + drm_gem_fb_destroy(fb);
> +}
> +
> +static struct drm_framebuffer_funcs fb_funcs = {
> + .destroy = fb_destroy,
> +};
> +
> +static struct drm_framebuffer *fb_create(struct drm_device *dev,
> + struct drm_file *filp, const struct drm_mode_fb_cmd2 *mode_cmd)
> +{
> + struct xen_drm_front_drm_info *drm_info = dev->dev_private;
> + static struct drm_framebuffer *fb;
> + struct drm_gem_object *gem_obj;
> + int ret;
> +
> + fb = drm_gem_fb_create_with_funcs(dev, filp, mode_cmd, &fb_funcs);
> + if (IS_ERR_OR_NULL(fb))
> + return fb;
> +
> + gem_obj = drm_gem_object_lookup(filp, mode_cmd->handles[0]);
> + if (!gem_obj) {
> + DRM_ERROR("Failed to lookup GEM object\n");
> + ret = -ENOENT;
> + goto fail;
> + }
> +
> + drm_gem_object_put_unlocked(gem_obj);
> +
> + ret = xen_drm_front_fb_attach(
> + drm_info->front_info,
> + xen_drm_front_dbuf_to_cookie(gem_obj),
> + xen_drm_front_fb_to_cookie(fb),
> + fb->width, fb->height, fb->format->format);
> + if (ret < 0) {
> + DRM_ERROR("Back failed to attach FB %p: %d\n", fb, ret);
> + goto fail;
> + }
> +
> + return fb;
> +
> +fail:
> + drm_gem_fb_destroy(fb);
> + return ERR_PTR(ret);
> +}
> +
> +static const struct drm_mode_config_funcs mode_config_funcs = {
> + .fb_create = fb_create,
> + .atomic_check = drm_atomic_helper_check,
> + .atomic_commit = drm_atomic_helper_commit,
> +};
> +
> +static void send_pending_event(struct xen_drm_front_drm_pipeline *pipeline)
> +{
> + struct drm_crtc *crtc = &pipeline->pipe.crtc;
> + struct drm_device *dev = crtc->dev;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&dev->event_lock, flags);
> + if (pipeline->pending_event)
> + drm_crtc_send_vblank_event(crtc, pipeline->pending_event);
> + pipeline->pending_event = NULL;
> + spin_unlock_irqrestore(&dev->event_lock, flags);
> +}
> +
> +static void display_enable(struct drm_simple_display_pipe *pipe,
> + struct drm_crtc_state *crtc_state)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(pipe);
> + struct drm_crtc *crtc = &pipe->crtc;
> + struct drm_framebuffer *fb = pipe->plane.state->fb;
> + int ret, idx;
> +
> + if (!drm_dev_enter(pipe->crtc.dev, &idx))
> + return;
> +
> + ret = xen_drm_front_mode_set(pipeline,
> + crtc->x, crtc->y, fb->width, fb->height,
> + fb->format->cpp[0] * 8,
> + xen_drm_front_fb_to_cookie(fb));
> +
> + if (ret) {
> + DRM_ERROR("Failed to enable display: %d\n", ret);
> + pipeline->conn_connected = false;
> + }
> +
> + drm_dev_exit(idx);
> +}
> +
> +static void display_disable(struct drm_simple_display_pipe *pipe)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(pipe);
> + int ret = 0, idx;
> +
> + if (drm_dev_enter(pipe->crtc.dev, &idx)) {
> + ret = xen_drm_front_mode_set(pipeline, 0, 0, 0, 0, 0,
> + xen_drm_front_fb_to_cookie(NULL));
> + drm_dev_exit(idx);
> + }
> + if (ret)
> + DRM_ERROR("Failed to disable display: %d\n", ret);
> +
> + /* Make sure we can restart with enabled connector next time */
> + pipeline->conn_connected = true;
> +
> + /* release stalled event if any */
> + send_pending_event(pipeline);
> +}
> +
> +void xen_drm_front_kms_on_frame_done(
> + struct xen_drm_front_drm_pipeline *pipeline,
> + uint64_t fb_cookie)
> +{
> + /*
> + * This runs in interrupt context, e.g. under
> + * drm_info->front_info->io_lock, so we cannot call _sync version
> + * to cancel the work
> + */
> + cancel_delayed_work(&pipeline->pflip_to_worker);
> +
> + send_pending_event(pipeline);
> +}
> +
> +static void pflip_to_worker(struct work_struct *work)
> +{
> + struct delayed_work *delayed_work = to_delayed_work(work);
> + struct xen_drm_front_drm_pipeline *pipeline =
> + container_of(delayed_work,
> + struct xen_drm_front_drm_pipeline,
> + pflip_to_worker);
> +
> + DRM_ERROR("Frame done timed-out, releasing");
> + send_pending_event(pipeline);
> +}
> +
> +static bool display_send_page_flip(struct drm_simple_display_pipe *pipe,
> + struct drm_plane_state *old_plane_state)
> +{
> + struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(
> + old_plane_state->state, &pipe->plane);
> +
> + /*
> + * If old_plane_state->fb is NULL and plane_state->fb is not,
> + * then this is an atomic commit which will enable display.
> + * If old_plane_state->fb is not NULL and plane_state->fb is,
> + * then this is an atomic commit which will disable display.
> + * Ignore these and do not send page flip as this framebuffer will be
> + * sent to the backend as a part of display_set_config call.
> + */
> + if (old_plane_state->fb && plane_state->fb) {
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(pipe);
> + struct xen_drm_front_drm_info *drm_info = pipeline->drm_info;
> + int ret;
> +
> + schedule_delayed_work(&pipeline->pflip_to_worker,
> + msecs_to_jiffies(FRAME_DONE_TO_MS));
> +
> + ret = xen_drm_front_page_flip(drm_info->front_info,
> + pipeline->index,
> + xen_drm_front_fb_to_cookie(plane_state->fb));
> + if (ret) {
> + DRM_ERROR("Failed to send page flip request to backend: %d\n", ret);
> +
> + pipeline->conn_connected = false;
> + /*
> + * Report the flip not handled, so pending event is
> + * sent, unblocking user-space.
> + */
> + return false;
> + }
> + /*
> + * Signal that page flip was handled, pending event will be sent
> + * on frame done event from the backend.
> + */
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static int display_prepare_fb(struct drm_simple_display_pipe *pipe,
> + struct drm_plane_state *plane_state)
> +{
> + return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
> +}
> +
> +static void display_update(struct drm_simple_display_pipe *pipe,
> + struct drm_plane_state *old_plane_state)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + to_xen_drm_pipeline(pipe);
> + struct drm_crtc *crtc = &pipe->crtc;
> + struct drm_pending_vblank_event *event;
> + int idx;
> +
> + event = crtc->state->event;
> + if (event) {
> + struct drm_device *dev = crtc->dev;
> + unsigned long flags;
> +
> + WARN_ON(pipeline->pending_event);
> +
> + spin_lock_irqsave(&dev->event_lock, flags);
> + crtc->state->event = NULL;
> +
> + pipeline->pending_event = event;
> + spin_unlock_irqrestore(&dev->event_lock, flags);
> +
> + }
> +
> + if (!drm_dev_enter(pipe->crtc.dev, &idx)) {
> + send_pending_event(pipeline);
> + return;
> + }
> +
> + /*
> + * Send page flip request to the backend *after* we have event cached
> + * above, so on page flip done event from the backend we can
> + * deliver it and there is no race condition between this code and
> + * event from the backend.
> + * If this is not a page flip, e.g. no flip done event from the backend
> + * is expected, then send now.
> + */
> + if (!display_send_page_flip(pipe, old_plane_state))
> + send_pending_event(pipeline);
> +
> + drm_dev_exit(idx);
> +}
> +
> +enum drm_mode_status display_mode_valid(struct drm_crtc *crtc,
> + const struct drm_display_mode *mode)
> +{
> + struct xen_drm_front_drm_pipeline *pipeline =
> + container_of(crtc,
> + struct xen_drm_front_drm_pipeline,
> + pipe.crtc);
> +
> + if (mode->hdisplay != pipeline->width)
> + return MODE_ERROR;
> +
> + if (mode->vdisplay != pipeline->height)
> + return MODE_ERROR;
> +
> + return MODE_OK;
> +}
> +
> +static const struct drm_simple_display_pipe_funcs display_funcs = {
> + .mode_valid = display_mode_valid,
> + .enable = display_enable,
> + .disable = display_disable,
> + .prepare_fb = display_prepare_fb,
> + .update = display_update,
> +};
> +
> +static int display_pipe_init(struct xen_drm_front_drm_info *drm_info,
> + int index, struct xen_drm_front_cfg_connector *cfg,
> + struct xen_drm_front_drm_pipeline *pipeline)
> +{
> + struct drm_device *dev = drm_info->drm_dev;
> + const uint32_t *formats;
> + int format_count;
> + int ret;
> +
> + pipeline->drm_info = drm_info;
> + pipeline->index = index;
> + pipeline->height = cfg->height;
> + pipeline->width = cfg->width;
> +
> + INIT_DELAYED_WORK(&pipeline->pflip_to_worker, pflip_to_worker);
> +
> + ret = xen_drm_front_conn_init(drm_info, &pipeline->conn);
> + if (ret)
> + return ret;
> +
> + formats = xen_drm_front_conn_get_formats(&format_count);
> +
> + return drm_simple_display_pipe_init(dev, &pipeline->pipe,
> + &display_funcs, formats, format_count,
> + NULL, &pipeline->conn);
> +}
> +
> +int xen_drm_front_kms_init(struct xen_drm_front_drm_info *drm_info)
> +{
> + struct drm_device *dev = drm_info->drm_dev;
> + int i, ret;
> +
> + drm_mode_config_init(dev);
> +
> + dev->mode_config.min_width = 0;
> + dev->mode_config.min_height = 0;
> + dev->mode_config.max_width = 4095;
> + dev->mode_config.max_height = 2047;
> + dev->mode_config.funcs = &mode_config_funcs;
> +
> + for (i = 0; i < drm_info->front_info->cfg.num_connectors; i++) {
> + struct xen_drm_front_cfg_connector *cfg =
> + &drm_info->front_info->cfg.connectors[i];
> + struct xen_drm_front_drm_pipeline *pipeline =
> + &drm_info->pipeline[i];
> +
> + ret = display_pipe_init(drm_info, i, cfg, pipeline);
> + if (ret) {
> + drm_mode_config_cleanup(dev);
> + return ret;
> + }
> + }
> +
> + drm_mode_config_reset(dev);
> + drm_kms_helper_poll_init(dev);
> + return 0;
> +}
> +
> +void xen_drm_front_kms_fini(struct xen_drm_front_drm_info *drm_info)
> +{
> + int i;
> +
> + for (i = 0; i < drm_info->front_info->cfg.num_connectors; i++) {
> + struct xen_drm_front_drm_pipeline *pipeline =
> + &drm_info->pipeline[i];
> +
> + cancel_delayed_work_sync(&pipeline->pflip_to_worker);
> +
> + send_pending_event(pipeline);
> + }
> +}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_kms.h b/drivers/gpu/drm/xen/xen_drm_front_kms.h
> new file mode 100644
> index 000000000000..1c3a64c36dbb
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_kms.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_KMS_H_
> +#define __XEN_DRM_FRONT_KMS_H_
> +
> +#include <linux/types.h>
> +
> +struct xen_drm_front_drm_info;
> +struct xen_drm_front_drm_pipeline;
> +
> +int xen_drm_front_kms_init(struct xen_drm_front_drm_info *drm_info);
> +
> +void xen_drm_front_kms_fini(struct xen_drm_front_drm_info *drm_info);
> +
> +void xen_drm_front_kms_on_frame_done(
> + struct xen_drm_front_drm_pipeline *pipeline,
> + uint64_t fb_cookie);
> +
> +#endif /* __XEN_DRM_FRONT_KMS_H_ */
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.c b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
> new file mode 100644
> index 000000000000..0fde2d8f7706
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c
> @@ -0,0 +1,432 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#include <drm/drmP.h>
> +
> +#if defined(CONFIG_X86)
> +#include <drm/drm_cache.h>
> +#endif
> +#include <linux/errno.h>
> +#include <linux/mm.h>
> +
> +#include <asm/xen/hypervisor.h>
> +#include <xen/balloon.h>
> +#include <xen/xen.h>
> +#include <xen/xenbus.h>
> +#include <xen/interface/io/ring.h>
> +#include <xen/interface/io/displif.h>
> +
> +#include "xen_drm_front.h"
> +#include "xen_drm_front_shbuf.h"
> +
> +struct xen_drm_front_shbuf_ops {
> + /*
> + * Calculate number of grefs required to handle this buffer,
> + * e.g. if grefs are required for page directory only or the buffer
> + * pages as well.
> + */
> + void (*calc_num_grefs)(struct xen_drm_front_shbuf *buf);
> + /* Fill page directory according to para-virtual display protocol. */
> + void (*fill_page_dir)(struct xen_drm_front_shbuf *buf);
> + /* Claim grant references for the pages of the buffer. */
> + int (*grant_refs_for_buffer)(struct xen_drm_front_shbuf *buf,
> + grant_ref_t *priv_gref_head, int gref_idx);
> + /* Map grant references of the buffer. */
> + int (*map)(struct xen_drm_front_shbuf *buf);
> + /* Unmap grant references of the buffer. */
> + int (*unmap)(struct xen_drm_front_shbuf *buf);
> +};
> +
> +grant_ref_t xen_drm_front_shbuf_get_dir_start(struct xen_drm_front_shbuf *buf)
> +{
> + if (!buf->grefs)
> + return GRANT_INVALID_REF;
> +
> + return buf->grefs[0];
> +}
> +
> +int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf)
> +{
> + if (buf->ops->map)
> + return buf->ops->map(buf);
> +
> + /* no need to map own grant references */
> + return 0;
> +}
> +
> +int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf)
> +{
> + if (buf->ops->unmap)
> + return buf->ops->unmap(buf);
> +
> + /* no need to unmap own grant references */
> + return 0;
> +}
> +
> +void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf)
> +{
> +#if defined(CONFIG_X86)
> + drm_clflush_pages(buf->pages, buf->num_pages);
> +#endif
> +}
> +
> +void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf)
> +{
> + if (buf->grefs) {
> + int i;
> +
> + for (i = 0; i < buf->num_grefs; i++)
> + if (buf->grefs[i] != GRANT_INVALID_REF)
> + gnttab_end_foreign_access(buf->grefs[i],
> + 0, 0UL);
> + }
> + kfree(buf->grefs);
> + kfree(buf->directory);
> + if (buf->sgt) {
> + sg_free_table(buf->sgt);
> + kvfree(buf->pages);
> + }
> + kfree(buf);
> +}
> +
> +/*
> + * number of grefs a page can hold with respect to the
> + * struct xendispl_page_directory header
> + */
> +#define XEN_DRM_NUM_GREFS_PER_PAGE ((PAGE_SIZE - \
> + offsetof(struct xendispl_page_directory, gref)) / \
> + sizeof(grant_ref_t))
> +
> +static int get_num_pages_dir(struct xen_drm_front_shbuf *buf)
> +{
> + /* number of pages the page directory consumes itself */
> + return DIV_ROUND_UP(buf->num_pages, XEN_DRM_NUM_GREFS_PER_PAGE);
> +}
> +
> +static void backend_calc_num_grefs(struct xen_drm_front_shbuf *buf)
> +{
> + /* only for pages the page directory consumes itself */
> + buf->num_grefs = get_num_pages_dir(buf);
> +}
> +
> +static void guest_calc_num_grefs(struct xen_drm_front_shbuf *buf)
> +{
> + /*
> + * number of pages the page directory consumes itself
> + * plus grefs for the buffer pages
> + */
> + buf->num_grefs = get_num_pages_dir(buf) + buf->num_pages;
> +}
> +
> +#define xen_page_to_vaddr(page) \
> + ((phys_addr_t)pfn_to_kaddr(page_to_xen_pfn(page)))
> +
> +static int backend_unmap(struct xen_drm_front_shbuf *buf)
> +{
> + struct gnttab_unmap_grant_ref *unmap_ops;
> + int i, ret;
> +
> + if (!buf->pages || !buf->backend_map_handles || !buf->grefs)
> + return 0;
> +
> + unmap_ops = kcalloc(buf->num_pages, sizeof(*unmap_ops),
> + GFP_KERNEL);
> + if (!unmap_ops) {
> + DRM_ERROR("Failed to get memory while unmapping\n");
> + return -ENOMEM;
> + }
> +
> + for (i = 0; i < buf->num_pages; i++) {
> + phys_addr_t addr;
> +
> + addr = xen_page_to_vaddr(buf->pages[i]);
> + gnttab_set_unmap_op(&unmap_ops[i], addr, GNTMAP_host_map,
> + buf->backend_map_handles[i]);
> + }
> +
> + ret = gnttab_unmap_refs(unmap_ops, NULL, buf->pages,
> + buf->num_pages);
> +
> + for (i = 0; i < buf->num_pages; i++) {
> + if (unlikely(unmap_ops[i].status != GNTST_okay))
> + DRM_ERROR("Failed to unmap page %d: %d\n",
> + i, unmap_ops[i].status);
> + }
> +
> + if (ret)
> + DRM_ERROR("Failed to unmap grant references, ret %d", ret);
> +
> + kfree(unmap_ops);
> + kfree(buf->backend_map_handles);
> + buf->backend_map_handles = NULL;
> + return ret;
> +}
> +
> +static int backend_map(struct xen_drm_front_shbuf *buf)
> +{
> + struct gnttab_map_grant_ref *map_ops = NULL;
> + unsigned char *ptr;
> + int ret, cur_gref, cur_dir_page, cur_page, grefs_left;
> +
> + map_ops = kcalloc(buf->num_pages, sizeof(*map_ops), GFP_KERNEL);
> + if (!map_ops)
> + return -ENOMEM;
> +
> + buf->backend_map_handles = kcalloc(buf->num_pages,
> + sizeof(*buf->backend_map_handles), GFP_KERNEL);
> + if (!buf->backend_map_handles) {
> + kfree(map_ops);
> + return -ENOMEM;
> + }
> +
> + /*
> + * read page directory to get grefs from the backend: for external
> + * buffer we only allocate buf->grefs for the page directory,
> + * so buf->num_grefs has number of pages in the page directory itself
> + */
> + ptr = buf->directory;
> + grefs_left = buf->num_pages;
> + cur_page = 0;
> + for (cur_dir_page = 0; cur_dir_page < buf->num_grefs; cur_dir_page++) {
> + struct xendispl_page_directory *page_dir =
> + (struct xendispl_page_directory *)ptr;
> + int to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
> +
> + if (to_copy > grefs_left)
> + to_copy = grefs_left;
> +
> + for (cur_gref = 0; cur_gref < to_copy; cur_gref++) {
> + phys_addr_t addr;
> +
> + addr = xen_page_to_vaddr(buf->pages[cur_page]);
> + gnttab_set_map_op(&map_ops[cur_page], addr,
> + GNTMAP_host_map,
> + page_dir->gref[cur_gref],
> + buf->xb_dev->otherend_id);
> + cur_page++;
> + }
> +
> + grefs_left -= to_copy;
> + ptr += PAGE_SIZE;
> + }
> + ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);
> +
> + /* save handles even if error, so we can unmap */
> + for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {
> + buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;
> + if (unlikely(map_ops[cur_page].status != GNTST_okay))
> + DRM_ERROR("Failed to map page %d: %d\n",
> + cur_page, map_ops[cur_page].status);
> + }
> +
> + if (ret) {
> + DRM_ERROR("Failed to map grant references, ret %d", ret);
> + backend_unmap(buf);
> + }
> +
> + kfree(map_ops);
> + return ret;
> +}
> +
> +static void backend_fill_page_dir(struct xen_drm_front_shbuf *buf)
> +{
> + struct xendispl_page_directory *page_dir;
> + unsigned char *ptr;
> + int i, num_pages_dir;
> +
> + ptr = buf->directory;
> + num_pages_dir = get_num_pages_dir(buf);
> +
> + /* fill only grefs for the page directory itself */
> + for (i = 0; i < num_pages_dir - 1; i++) {
> + page_dir = (struct xendispl_page_directory *)ptr;
> +
> + page_dir->gref_dir_next_page = buf->grefs[i + 1];
> + ptr += PAGE_SIZE;
> + }
> + /* last page must say there is no more pages */
> + page_dir = (struct xendispl_page_directory *)ptr;
> + page_dir->gref_dir_next_page = GRANT_INVALID_REF;
> +}
> +
> +static void guest_fill_page_dir(struct xen_drm_front_shbuf *buf)
> +{
> + unsigned char *ptr;
> + int cur_gref, grefs_left, to_copy, i, num_pages_dir;
> +
> + ptr = buf->directory;
> + num_pages_dir = get_num_pages_dir(buf);
> +
> + /*
> + * while copying, skip grefs at start, they are for pages
> + * granted for the page directory itself
> + */
> + cur_gref = num_pages_dir;
> + grefs_left = buf->num_pages;
> + for (i = 0; i < num_pages_dir; i++) {
> + struct xendispl_page_directory *page_dir =
> + (struct xendispl_page_directory *)ptr;
> +
> + if (grefs_left <= XEN_DRM_NUM_GREFS_PER_PAGE) {
> + to_copy = grefs_left;
> + page_dir->gref_dir_next_page = GRANT_INVALID_REF;
> + } else {
> + to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
> + page_dir->gref_dir_next_page = buf->grefs[i + 1];
> + }
> + memcpy(&page_dir->gref, &buf->grefs[cur_gref],
> + to_copy * sizeof(grant_ref_t));
> + ptr += PAGE_SIZE;
> + grefs_left -= to_copy;
> + cur_gref += to_copy;
> + }
> +}
> +
> +static int guest_grant_refs_for_buffer(struct xen_drm_front_shbuf *buf,
> + grant_ref_t *priv_gref_head, int gref_idx)
> +{
> + int i, cur_ref, otherend_id;
> +
> + otherend_id = buf->xb_dev->otherend_id;
> + for (i = 0; i < buf->num_pages; i++) {
> + cur_ref = gnttab_claim_grant_reference(priv_gref_head);
> + if (cur_ref < 0)
> + return cur_ref;
> + gnttab_grant_foreign_access_ref(cur_ref, otherend_id,
> + xen_page_to_gfn(buf->pages[i]), 0);
> + buf->grefs[gref_idx++] = cur_ref;
> + }
> + return 0;
> +}
> +
> +static int grant_references(struct xen_drm_front_shbuf *buf)
> +{
> + grant_ref_t priv_gref_head;
> + int ret, i, j, cur_ref;
> + int otherend_id, num_pages_dir;
> +
> + ret = gnttab_alloc_grant_references(buf->num_grefs, &priv_gref_head);
> + if (ret < 0) {
> + DRM_ERROR("Cannot allocate grant references\n");
> + return ret;
> + }
> + otherend_id = buf->xb_dev->otherend_id;
> + j = 0;
> + num_pages_dir = get_num_pages_dir(buf);
> + for (i = 0; i < num_pages_dir; i++) {
> + unsigned long frame;
> +
> + cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
> + if (cur_ref < 0)
> + return cur_ref;
> +
> + frame = xen_page_to_gfn(virt_to_page(buf->directory +
> + PAGE_SIZE * i));
> + gnttab_grant_foreign_access_ref(cur_ref, otherend_id,
> + frame, 0);
> + buf->grefs[j++] = cur_ref;
> + }
> +
> + if (buf->ops->grant_refs_for_buffer) {
> + ret = buf->ops->grant_refs_for_buffer(buf, &priv_gref_head, j);
> + if (ret)
> + return ret;
> + }
> +
> + gnttab_free_grant_references(priv_gref_head);
> + return 0;
> +}
> +
> +static int alloc_storage(struct xen_drm_front_shbuf *buf)
> +{
> + if (buf->sgt) {
> + buf->pages = kvmalloc_array(buf->num_pages,
> + sizeof(struct page *), GFP_KERNEL);
> + if (!buf->pages)
> + return -ENOMEM;
> +
> + if (drm_prime_sg_to_page_addr_arrays(buf->sgt, buf->pages,
> + NULL, buf->num_pages) < 0)
> + return -EINVAL;
> + }
> +
> + buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), GFP_KERNEL);
> + if (!buf->grefs)
> + return -ENOMEM;
> +
> + buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, GFP_KERNEL);
> + if (!buf->directory)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +/*
> + * For be allocated buffers we don't need grant_refs_for_buffer as those
> + * grant references are allocated at backend side
> + */
> +static const struct xen_drm_front_shbuf_ops backend_ops = {
> + .calc_num_grefs = backend_calc_num_grefs,
> + .fill_page_dir = backend_fill_page_dir,
> + .map = backend_map,
> + .unmap = backend_unmap
> +};
> +
> +/* For locally granted references we do not need to map/unmap the references */
> +static const struct xen_drm_front_shbuf_ops local_ops = {
> + .calc_num_grefs = guest_calc_num_grefs,
> + .fill_page_dir = guest_fill_page_dir,
> + .grant_refs_for_buffer = guest_grant_refs_for_buffer,
> +};
> +
> +struct xen_drm_front_shbuf *xen_drm_front_shbuf_alloc(
> + struct xen_drm_front_shbuf_cfg *cfg)
> +{
> + struct xen_drm_front_shbuf *buf;
> + int ret;
> +
> + /* either pages or sgt, not both */
> + if (unlikely(cfg->pages && cfg->sgt)) {
> + DRM_ERROR("Cannot handle buffer allocation with both pages and sg table provided\n");
> + return NULL;
> + }
> +
> + buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> + if (!buf)
> + return NULL;
> +
> + if (cfg->be_alloc)
> + buf->ops = &backend_ops;
> + else
> + buf->ops = &local_ops;
> +
> + buf->xb_dev = cfg->xb_dev;
> + buf->num_pages = DIV_ROUND_UP(cfg->size, PAGE_SIZE);
> + buf->sgt = cfg->sgt;
> + buf->pages = cfg->pages;
> +
> + buf->ops->calc_num_grefs(buf);
> +
> + ret = alloc_storage(buf);
> + if (ret)
> + goto fail;
> +
> + ret = grant_references(buf);
> + if (ret)
> + goto fail;
> +
> + buf->ops->fill_page_dir(buf);
> +
> + return buf;
> +
> +fail:
> + xen_drm_front_shbuf_free(buf);
> + return ERR_PTR(ret);
> +}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.h b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
> new file mode 100644
> index 000000000000..6c4fbc68f328
> --- /dev/null
> +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h
> @@ -0,0 +1,72 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +
> +/*
> + * Xen para-virtual DRM device
> + *
> + * Copyright (C) 2016-2018 EPAM Systems Inc.
> + *
> + * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> + */
> +
> +#ifndef __XEN_DRM_FRONT_SHBUF_H_
> +#define __XEN_DRM_FRONT_SHBUF_H_
> +
> +#include <linux/kernel.h>
> +#include <linux/scatterlist.h>
> +
> +#include <xen/grant_table.h>
> +
> +struct xen_drm_front_shbuf {
> + /*
> + * number of references granted for the backend use:
> + * - for allocated/imported dma-buf's this holds number of grant
> + * references for the page directory and pages of the buffer
> + * - for the buffer provided by the backend this holds number of
> + * grant references for the page directory as grant references for
> + * the buffer will be provided by the backend
> + */
> + int num_grefs;
> + grant_ref_t *grefs;
> + unsigned char *directory;
> +
> + /*
> + * there are 2 ways to provide backing storage for this shared buffer:
> + * either pages or sgt. if buffer created from sgt then we own
> + * the pages and must free those ourselves on closure
> + */
> + int num_pages;
> + struct page **pages;
> +
> + struct sg_table *sgt;
> +
> + struct xenbus_device *xb_dev;
> +
> + /* these are the ops used internally depending on be_alloc mode */
> + const struct xen_drm_front_shbuf_ops *ops;
> +
> + /* Xen map handles for the buffer allocated by the backend */
> + grant_handle_t *backend_map_handles;
> +};
> +
> +struct xen_drm_front_shbuf_cfg {
> + struct xenbus_device *xb_dev;
> + size_t size;
> + struct page **pages;
> + struct sg_table *sgt;
> + bool be_alloc;
> +};
> +
> +struct xen_drm_front_shbuf *xen_drm_front_shbuf_alloc(
> + struct xen_drm_front_shbuf_cfg *cfg);
> +
> +grant_ref_t xen_drm_front_shbuf_get_dir_start(struct xen_drm_front_shbuf *buf);
> +
> +int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf);
> +
> +int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf);
> +
> +void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf);
> +
> +void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf);
> +
> +#endif /* __XEN_DRM_FRONT_SHBUF_H_ */
> --
> 2.7.4
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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