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SubjectRe: [PATCH v4 10/25] nvdimm: Add driver for OpenCAPI Persistent Memory
On Wed, Apr 1, 2020 at 1:49 AM Dan Williams <dan.j.williams@intel.com> wrote:
>
> On Sun, Mar 29, 2020 at 10:23 PM Alastair D'Silva <alastair@d-silva.org> wrote:
> >
> > This driver exposes LPC memory on OpenCAPI pmem cards
> > as an NVDIMM, allowing the existing nvram infrastructure
> > to be used.
> >
> > Namespace metadata is stored on the media itself, so
> > scm_reserve_metadata() maps 1 section's worth of PMEM storage
> > at the start to hold this. The rest of the PMEM range is registered
> > with libnvdimm as an nvdimm. ndctl_config_read/write/size() provide
> > callbacks to libnvdimm to access the metadata.
> >
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> > drivers/nvdimm/Kconfig | 2 +
> > drivers/nvdimm/Makefile | 1 +
> > drivers/nvdimm/ocxl/Kconfig | 15 ++
> > drivers/nvdimm/ocxl/Makefile | 7 +
> > drivers/nvdimm/ocxl/main.c | 476 +++++++++++++++++++++++++++++++++
> > drivers/nvdimm/ocxl/ocxlpmem.h | 23 ++
> > 6 files changed, 524 insertions(+)
> > create mode 100644 drivers/nvdimm/ocxl/Kconfig
> > create mode 100644 drivers/nvdimm/ocxl/Makefile
> > create mode 100644 drivers/nvdimm/ocxl/main.c
> > create mode 100644 drivers/nvdimm/ocxl/ocxlpmem.h
> >
> > diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
> > index b7d1eb38b27d..368328637182 100644
> > --- a/drivers/nvdimm/Kconfig
> > +++ b/drivers/nvdimm/Kconfig
> > @@ -131,4 +131,6 @@ config NVDIMM_TEST_BUILD
> > core devm_memremap_pages() implementation and other
> > infrastructure.
> >
> > +source "drivers/nvdimm/ocxl/Kconfig"
> > +
> > endif
> > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
> > index 29203f3d3069..bc02be11c794 100644
> > --- a/drivers/nvdimm/Makefile
> > +++ b/drivers/nvdimm/Makefile
> > @@ -33,3 +33,4 @@ libnvdimm-$(CONFIG_NVDIMM_KEYS) += security.o
> > TOOLS := ../../tools
> > TEST_SRC := $(TOOLS)/testing/nvdimm/test
> > obj-$(CONFIG_NVDIMM_TEST_BUILD) += $(TEST_SRC)/iomap.o
> > +obj-$(CONFIG_LIBNVDIMM) += ocxl/
> > diff --git a/drivers/nvdimm/ocxl/Kconfig b/drivers/nvdimm/ocxl/Kconfig
> > new file mode 100644
> > index 000000000000..c5d927520920
> > --- /dev/null
> > +++ b/drivers/nvdimm/ocxl/Kconfig
> > @@ -0,0 +1,15 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +if LIBNVDIMM
> > +
> > +config OCXL_PMEM
> > + tristate "OpenCAPI Persistent Memory"
> > + depends on LIBNVDIMM && PPC_POWERNV && PCI && EEH && ZONE_DEVICE && OCXL
>
> Does OXCL_PMEM itself have any CONFIG_ZONE_DEVICE dependencies? That's
> more a function of CONFIG_DEV_DAX and CONFIG_FS_DAX. Doesn't OCXL
> already depend on CONFIG_PCI?
>
>
> > + help
> > + Exposes devices that implement the OpenCAPI Storage Class Memory
> > + specification as persistent memory regions. You may also want
> > + DEV_DAX, DEV_DAX_PMEM & FS_DAX if you plan on using DAX devices
> > + stacked on top of this driver.
> > +
> > + Select N if unsure.
> > +
> > +endif
> > diff --git a/drivers/nvdimm/ocxl/Makefile b/drivers/nvdimm/ocxl/Makefile
> > new file mode 100644
> > index 000000000000..e0e8ade1987a
> > --- /dev/null
> > +++ b/drivers/nvdimm/ocxl/Makefile
> > @@ -0,0 +1,7 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +ccflags-$(CONFIG_PPC_WERROR) += -Werror
> > +
> > +obj-$(CONFIG_OCXL_PMEM) += ocxlpmem.o
> > +
> > +ocxlpmem-y := main.o
> > \ No newline at end of file
> > diff --git a/drivers/nvdimm/ocxl/main.c b/drivers/nvdimm/ocxl/main.c
> > new file mode 100644
> > index 000000000000..c0066fedf9cc
> > --- /dev/null
> > +++ b/drivers/nvdimm/ocxl/main.c
> > @@ -0,0 +1,476 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +// Copyright 2020 IBM Corp.
> > +
> > +/*
> > + * A driver for OpenCAPI devices that implement the Storage Class
> > + * Memory specification.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <misc/ocxl.h>
> > +#include <linux/ndctl.h>
> > +#include <linux/mm_types.h>
> > +#include <linux/memory_hotplug.h>
> > +#include "ocxlpmem.h"
> > +
> > +static const struct pci_device_id pci_tbl[] = {
> > + { PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0625), },
> > + { }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(pci, pci_tbl);
> > +
> > +#define NUM_MINORS 256 // Total to reserve
> > +
> > +static dev_t ocxlpmem_dev;
> > +static struct class *ocxlpmem_class;
> > +static struct mutex minors_idr_lock;
> > +static struct idr minors_idr;
> > +
> > +/**
> > + * ndctl_config_write() - Handle a ND_CMD_SET_CONFIG_DATA command from ndctl
> > + * @ocxlpmem: the device metadata
> > + * @command: the incoming data to write
> > + * Return: 0 on success, negative on failure
> > + */
> > +static int ndctl_config_write(struct ocxlpmem *ocxlpmem,
> > + struct nd_cmd_set_config_hdr *command)
> > +{
> > + if (command->in_offset + command->in_length > LABEL_AREA_SIZE)
> > + return -EINVAL;
> > +
> > + memcpy_flushcache(ocxlpmem->metadata_addr + command->in_offset,
> > + command->in_buf, command->in_length);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * ndctl_config_read() - Handle a ND_CMD_GET_CONFIG_DATA command from ndctl
> > + * @ocxlpmem: the device metadata
> > + * @command: the read request
> > + * Return: 0 on success, negative on failure
> > + */
> > +static int ndctl_config_read(struct ocxlpmem *ocxlpmem,
> > + struct nd_cmd_get_config_data_hdr *command)
> > +{
> > + if (command->in_offset + command->in_length > LABEL_AREA_SIZE)
> > + return -EINVAL;
> > +
> > + memcpy_mcsafe(command->out_buf,
> > + ocxlpmem->metadata_addr + command->in_offset,
> > + command->in_length);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * ndctl_config_size() - Handle a ND_CMD_GET_CONFIG_SIZE command from ndctl
> > + * @command: the read request
> > + * Return: 0 on success, negative on failure
> > + */
> > +static int ndctl_config_size(struct nd_cmd_get_config_size *command)
> > +{
> > + command->status = 0;
> > + command->config_size = LABEL_AREA_SIZE;
> > + command->max_xfer = PAGE_SIZE;
> > +
> > + return 0;
> > +}
> > +
> > +static int ndctl(struct nvdimm_bus_descriptor *nd_desc,
> > + struct nvdimm *nvdimm,
> > + unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
> > +{
> > + struct ocxlpmem *ocxlpmem = container_of(nd_desc,
> > + struct ocxlpmem, bus_desc);
> > +
> > + switch (cmd) {
> > + case ND_CMD_GET_CONFIG_SIZE:
> > + *cmd_rc = ndctl_config_size(buf);
> > + return 0;
> > +
> > + case ND_CMD_GET_CONFIG_DATA:
> > + *cmd_rc = ndctl_config_read(ocxlpmem, buf);
> > + return 0;
> > +
> > + case ND_CMD_SET_CONFIG_DATA:
> > + *cmd_rc = ndctl_config_write(ocxlpmem, buf);
> > + return 0;
> > +
> > + default:
> > + return -ENOTTY;
> > + }
> > +}
> > +
> > +/**
> > + * reserve_metadata() - Reserve space for nvdimm metadata
> > + * @ocxlpmem: the device metadata
> > + * @lpc_mem: The resource representing the LPC memory of the OpenCAPI device
> > + */
> > +static int reserve_metadata(struct ocxlpmem *ocxlpmem,
> > + struct resource *lpc_mem)
> > +{
> > + ocxlpmem->metadata_addr = devm_memremap(&ocxlpmem->dev, lpc_mem->start,
> > + LABEL_AREA_SIZE, MEMREMAP_WB);
> > + if (IS_ERR(ocxlpmem->metadata_addr))
> > + return PTR_ERR(ocxlpmem->metadata_addr);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * register_lpc_mem() - Discover persistent memory on a device and register it with the NVDIMM subsystem
> > + * @ocxlpmem: the device metadata
> > + * Return: 0 on success
> > + */
> > +static int register_lpc_mem(struct ocxlpmem *ocxlpmem)
> > +{
> > + struct nd_region_desc region_desc;
> > + struct nd_mapping_desc nd_mapping_desc;
> > + struct resource *lpc_mem;
> > + const struct ocxl_afu_config *config;
> > + const struct ocxl_fn_config *fn_config;
> > + int rc;
> > + unsigned long nvdimm_cmd_mask = 0;
> > + unsigned long nvdimm_flags = 0;
> > + int target_node;
> > + char serial[16 + 1];
> > +
> > + // Set up the reserved metadata area
> > + rc = ocxl_afu_map_lpc_mem(ocxlpmem->ocxl_afu);
> > + if (rc < 0)
> > + return rc;
> > +
> > + lpc_mem = ocxl_afu_lpc_mem(ocxlpmem->ocxl_afu);
> > + if (!lpc_mem || !lpc_mem->start)
> > + return -EINVAL;
> > +
> > + config = ocxl_afu_config(ocxlpmem->ocxl_afu);
> > + fn_config = ocxl_function_config(ocxlpmem->ocxl_fn);
> > +
> > + rc = reserve_metadata(ocxlpmem, lpc_mem);
> > + if (rc)
> > + return rc;
> > +
> > + ocxlpmem->bus_desc.provider_name = "ocxlpmem";
> > + ocxlpmem->bus_desc.ndctl = ndctl;
> > + ocxlpmem->bus_desc.module = THIS_MODULE;
> > +
> > + ocxlpmem->nvdimm_bus = nvdimm_bus_register(&ocxlpmem->dev,
> > + &ocxlpmem->bus_desc);
> > + if (!ocxlpmem->nvdimm_bus)
> > + return -EINVAL;
> > +
> > + ocxlpmem->pmem_res.start = (u64)lpc_mem->start + LABEL_AREA_SIZE;
> > + ocxlpmem->pmem_res.end = (u64)lpc_mem->start + config->lpc_mem_size - 1;
> > + ocxlpmem->pmem_res.name = "OpenCAPI persistent memory";
> > +
> > + set_bit(ND_CMD_GET_CONFIG_SIZE, &nvdimm_cmd_mask);
> > + set_bit(ND_CMD_GET_CONFIG_DATA, &nvdimm_cmd_mask);
> > + set_bit(ND_CMD_SET_CONFIG_DATA, &nvdimm_cmd_mask);
> > +
> > + set_bit(NDD_ALIASING, &nvdimm_flags);
> > +
> > + snprintf(serial, sizeof(serial), "%llx", fn_config->serial);
> > + nd_mapping_desc.nvdimm = nvdimm_create(ocxlpmem->nvdimm_bus, ocxlpmem,
> > + NULL, nvdimm_flags,
> > + nvdimm_cmd_mask, 0, NULL);
> > + if (!nd_mapping_desc.nvdimm)
> > + return -ENOMEM;
> > +
> > + if (nvdimm_bus_check_dimm_count(ocxlpmem->nvdimm_bus, 1))
> > + return -EINVAL;
> > +
> > + nd_mapping_desc.start = ocxlpmem->pmem_res.start;
> > + nd_mapping_desc.size = resource_size(&ocxlpmem->pmem_res);
> > + nd_mapping_desc.position = 0;
> > +
> > + ocxlpmem->nd_set.cookie1 = fn_config->serial;
> > + ocxlpmem->nd_set.cookie2 = fn_config->serial;
> > +
> > + target_node = of_node_to_nid(ocxlpmem->pdev->dev.of_node);
> > +
> > + memset(&region_desc, 0, sizeof(region_desc));
> > + region_desc.res = &ocxlpmem->pmem_res;
> > + region_desc.numa_node = NUMA_NO_NODE;
> > + region_desc.target_node = target_node;
> > + region_desc.num_mappings = 1;
> > + region_desc.mapping = &nd_mapping_desc;
> > + region_desc.nd_set = &ocxlpmem->nd_set;
> > +
> > + set_bit(ND_REGION_PAGEMAP, &region_desc.flags);
> > + /*
> > + * NB: libnvdimm copies the data from ndr_desc into it's own
> > + * structures so passing a stack pointer is fine.
> > + */
> > + ocxlpmem->nd_region = nvdimm_pmem_region_create(ocxlpmem->nvdimm_bus,
> > + &region_desc);
> > + if (!ocxlpmem->nd_region)
> > + return -EINVAL;
> > +
> > + dev_info(&ocxlpmem->dev,
> > + "Onlining %lluMB of persistent memory\n",
> > + nd_mapping_desc.size / SZ_1M);
> > +
> > + return 0;
> > +}
> > +
> > +/**
> > + * allocate_minor() - Allocate a minor number to use for an OpenCAPI pmem device
> > + * @ocxlpmem: the device metadata
> > + * Return: the allocated minor number
> > + */
> > +static int allocate_minor(struct ocxlpmem *ocxlpmem)
> > +{
> > + int minor;
> > +
> > + mutex_lock(&minors_idr_lock);
> > + minor = idr_alloc(&minors_idr, ocxlpmem, 0, NUM_MINORS, GFP_KERNEL);
> > + mutex_unlock(&minors_idr_lock);
> > + return minor;
> > +}
> > +
> > +static void free_minor(struct ocxlpmem *ocxlpmem)
> > +{
> > + mutex_lock(&minors_idr_lock);
> > + idr_remove(&minors_idr, MINOR(ocxlpmem->dev.devt));
> > + mutex_unlock(&minors_idr_lock);
> > +}
> > +
> > +/**
> > + * free_ocxlpmem() - Free all members of an ocxlpmem struct
> > + * @ocxlpmem: the device struct to clear
> > + */
> > +static void free_ocxlpmem(struct ocxlpmem *ocxlpmem)
> > +{
> > + int rc;
> > +
> > + free_minor(ocxlpmem);
> > +
> > + if (ocxlpmem->ocxl_context) {
> > + rc = ocxl_context_detach(ocxlpmem->ocxl_context);
> > + if (rc == -EBUSY)
> > + dev_warn(&ocxlpmem->dev, "Timeout detaching ocxl context\n");
> > + else
> > + ocxl_context_free(ocxlpmem->ocxl_context);
> > + }
> > +
> > + if (ocxlpmem->ocxl_afu)
> > + ocxl_afu_put(ocxlpmem->ocxl_afu);
> > +
> > + if (ocxlpmem->ocxl_fn)
> > + ocxl_function_close(ocxlpmem->ocxl_fn);
> > +
> > + pci_dev_put(ocxlpmem->pdev);
> > +
> > + kfree(ocxlpmem);
> > +}
> > +
> > +/**
> > + * free_ocxlpmem_dev() - Free an OpenCAPI persistent memory device
> > + * @dev: The device struct
> > + */
> > +static void free_ocxlpmem_dev(struct device *dev)
> > +{
> > + struct ocxlpmem *ocxlpmem = container_of(dev, struct ocxlpmem, dev);
> > +
> > + free_ocxlpmem(ocxlpmem);
> > +}
> > +
> > +/**
> > + * ocxlpmem_register() - Register an OpenCAPI pmem device with the kernel
> > + * @ocxlpmem: the device metadata
> > + * Return: 0 on success, negative on failure
> > + */
> > +static int ocxlpmem_register(struct ocxlpmem *ocxlpmem)
> > +{
> > + int rc;
> > + int minor = allocate_minor(ocxlpmem);
> > +
> > + if (minor < 0)
> > + return minor;
> > +
> > + ocxlpmem->dev.release = free_ocxlpmem_dev;
> > + rc = dev_set_name(&ocxlpmem->dev, "ocxlpmem%d", minor);
> > + if (rc < 0)
> > + return rc;
> > +
> > + ocxlpmem->dev.devt = MKDEV(MAJOR(ocxlpmem_dev), minor);
> > + ocxlpmem->dev.class = ocxlpmem_class;
> > + ocxlpmem->dev.parent = &ocxlpmem->pdev->dev;
> > +
> > + return device_register(&ocxlpmem->dev);
>
> You lost me, why does this need it's own ioctl path and device node?
> I'd expect you you'd tunnel the commands you need through the existing
> infrastructure ideally with an eye for cross-arch compatibility. This
> is a fundamental concern that probably has significant implications
> for what follows.

At a minimum this device registration should move to the end of the
patchset once all the libnvdimm generic enabling is done. Even then I
think the libnvdimm core has all the hooks you need to provide device
specific enabling *through* the existing interfaces. Have a look at
the how the ACPI NFIT bus driver provides "nfit/" scoped sysfs
attributes and tunnels "struct nd_cmd_pkg" ioctl invocations to either
the bus or "dimm" level device objects. The dimm security model is an
example of an implementation that wraps a libnvdimm-generic sysfs
front-end to an intel-specific-device backend. It would be unfortunate
to need to invent another ABI.

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