vhost: support PACKED when setting-getting vring_base

Use the right structs for PACKED or split vqs when setting and
getting the vring base.

Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Message-Id: <20230424225031.18947-3-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 1f80eac5d6ae05f1bf50e6d6820e02ff1fe0a7d0..60c9ebd629dd159d0ceb8a0c14f96091be193753 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1600,17 +1600,25 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
                        r = -EFAULT;
                        break;
                }
-               if (s.num > 0xffff) {
-                       r = -EINVAL;
-                       break;
+               if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+                       vq->last_avail_idx = s.num & 0xffff;
+                       vq->last_used_idx = (s.num >> 16) & 0xffff;
+               } else {
+                       if (s.num > 0xffff) {
+                               r = -EINVAL;
+                               break;
+                       }
+                       vq->last_avail_idx = s.num;
                }
-               vq->last_avail_idx = s.num;
                /* Forget the cached index value. */
                vq->avail_idx = vq->last_avail_idx;
                break;
        case VHOST_GET_VRING_BASE:
                s.index = idx;
-               s.num = vq->last_avail_idx;
+               if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+                       s.num = (u32)vq->last_avail_idx | ((u32)vq->last_used_idx << 16);
+               else
+                       s.num = vq->last_avail_idx;
                if (copy_to_user(argp, &s, sizeof s))
                        r = -EFAULT;
                break;

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 305ec8593d46a4643328223e9d5dcba6aa24d712..fc900be504b38e48d7c74f96e78d825d4a2a909e 100644 (file)
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -92,13 +92,17 @@ struct vhost_virtqueue {
        /* The routine to call when the Guest pings us, or timeout. */
        vhost_work_fn_t handle_kick;
 
-       /* Last available index we saw. */
+       /* Last available index we saw.
+        * Values are limited to 0x7fff, and the high bit is used as
+        * a wrap counter when using VIRTIO_F_RING_PACKED. */
        u16 last_avail_idx;
 
        /* Caches available index value from user. */
        u16 avail_idx;
 
-       /* Last index we used. */
+       /* Last index we used.
+        * Values are limited to 0x7fff, and the high bit is used as
+        * a wrap counter when using VIRTIO_F_RING_PACKED. */
        u16 last_used_idx;
 
        /* Used flags */