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Subject[PATCH 16/52] virtio-fs: Add VIRTIO_PCI_CAP_SHARED_MEMORY_CFG and utility to find them
Date
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

The shm cap defines a capability to allow 64bit size chunks at 64 bit
size offsets into a bar. There can be multiple such chunks on any one
device.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
fs/fuse/virtio_fs.c | 69 +++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/virtio_pci.h | 10 ++++++
2 files changed, 79 insertions(+)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 87b7e42a6763..cd916943205e 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_fs.h>
+#include <uapi/linux/virtio_pci.h>
#include "fuse_i.h"

enum {
@@ -57,6 +58,74 @@ struct virtio_fs {
size_t window_len;
};

+/* TODO: This should be in a PCI file somewhere */
+static int virtio_pci_find_shm_cap(struct pci_dev *dev,
+ u8 required_id,
+ u8 *bar, u64 *offset, u64 *len)
+{
+ int pos;
+
+ for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
+ pos > 0;
+ pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
+ u8 type, cap_len, id;
+ u32 tmp32;
+ u64 res_offset, res_length;
+
+ pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+ cfg_type),
+ &type);
+ if (type != VIRTIO_PCI_CAP_SHARED_MEMORY_CFG)
+ continue;
+
+ pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+ cap_len),
+ &cap_len);
+ if (cap_len != sizeof(struct virtio_pci_shm_cap)) {
+ printk(KERN_ERR "%s: shm cap with bad size offset: %d size: %d\n",
+ __func__, pos, cap_len);
+ continue;
+ };
+
+ pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_shm_cap,
+ id),
+ &id);
+ if (id != required_id)
+ continue;
+
+ /* Type, and ID match, looks good */
+ pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+ bar),
+ bar);
+
+ /* Read the lower 32bit of length and offset */
+ pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap, offset),
+ &tmp32);
+ res_offset = tmp32;
+ pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap, length),
+ &tmp32);
+ res_length = tmp32;
+
+ /* and now the top half */
+ pci_read_config_dword(dev,
+ pos + offsetof(struct virtio_pci_shm_cap,
+ offset_hi),
+ &tmp32);
+ res_offset |= ((u64)tmp32) << 32;
+ pci_read_config_dword(dev,
+ pos + offsetof(struct virtio_pci_shm_cap,
+ length_hi),
+ &tmp32);
+ res_length |= ((u64)tmp32) << 32;
+
+ *offset = res_offset;
+ *len = res_length;
+
+ return pos;
+ }
+ return 0;
+}
+
static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
{
struct virtio_fs *fs = vq->vdev->priv;
diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index 90007a1abcab..2e6072b5a7c9 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -113,6 +113,8 @@
#define VIRTIO_PCI_CAP_DEVICE_CFG 4
/* PCI configuration access */
#define VIRTIO_PCI_CAP_PCI_CFG 5
+/* Additional shared memory capability */
+#define VIRTIO_PCI_CAP_SHARED_MEMORY_CFG 8

/* This is the PCI capability header: */
struct virtio_pci_cap {
@@ -163,6 +165,14 @@ struct virtio_pci_cfg_cap {
__u8 pci_cfg_data[4]; /* Data for BAR access. */
};

+/* Fields in VIRTIO_PCI_CAP_SHARED_MEMORY_CFG */
+struct virtio_pci_shm_cap {
+ struct virtio_pci_cap cap;
+ __le32 offset_hi; /* Most sig 32 bits of offset */
+ __le32 length_hi; /* Most sig 32 bits of length */
+ __u8 id; /* To distinguish shm chunks */
+};
+
/* Macro versions of offsets for the Old Timers! */
#define VIRTIO_PCI_CAP_VNDR 0
#define VIRTIO_PCI_CAP_NEXT 1
--
2.13.6
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