[PATCH v2 15/30] virtio: Implement get_shm_region for PCI transport

Vivek Goyal
2019-05-15T19:28:48Z

From: Sebastien Boeuf <sebastien.boeuf@intel.com>

On PCI the shm regions are found using capability entries;
find a region by searching for the capability.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
drivers/virtio/virtio_pci_modern.c | 108 +++++++++++++++++++++++++++++
include/uapi/linux/virtio_pci.h | 10 +++
2 files changed, 118 insertions(+)

diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index 07571daccfec..51c9e6eca5ac 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -446,6 +446,112 @@ static void del_vq(struct virtio_pci_vq_info *info)
vring_del_virtqueue(vq);
}

+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 bool vp_get_shm_region(struct virtio_device *vdev,
+ struct virtio_shm_region *region, u8 id)
+{
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ struct pci_dev *pci_dev = vp_dev->pci_dev;
+ u8 bar;
+ u64 offset, len;
+ phys_addr_t phys_addr;
+ size_t bar_len;
+ char *bar_name;
+ int ret;
+
+ if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len)) {
+ return false;
+ }
+
+ ret = pci_request_region(pci_dev, bar, "virtio-pci-shm");
+ if (ret < 0) {
+ dev_err(&pci_dev->dev, "%s: failed to request BAR\n",
+ __func__);
+ return false;
+ }
+
+ phys_addr = pci_resource_start(pci_dev, bar);
+ bar_len = pci_resource_len(pci_dev, bar);
+
+ if (offset + len > bar_len) {
+ dev_err(&pci_dev->dev,
+ "%s: bar shorter than cap offset+len\n",
+ __func__);
+ return false;
+ }
+
+ region->len = len;
+ region->addr = (u64) phys_addr + offset;
+
+ return true;
+}
+
static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
.get = NULL,
.set = NULL,
@@ -460,6 +566,7 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
.bus_name = vp_bus_name,
.set_vq_affinity = vp_set_vq_affinity,
.get_vq_affinity = vp_get_vq_affinity,
+ .get_shm_region = vp_get_shm_region,
};

static const struct virtio_config_ops virtio_pci_config_ops = {
@@ -476,6 +583,7 @@ static const struct virtio_config_ops virtio_pci_config_ops = {
.bus_name = vp_bus_name,
.set_vq_affinity = vp_set_vq_affinity,
.get_vq_affinity = vp_get_vq_affinity,
+ .get_shm_region = vp_get_shm_region,
};

/**
diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index 90007a1abcab..31841a60a4ad 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
--
2.20.1