[PATCH v2 2/3] vhost: support PACKED when setting-getting vring_base

Shannon Nelson
2023-04-24T22:50:30Z

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

Signed-off-by: Shannon Nelson <shannon.nelson at amd.com>
---
 drivers/vhost/vhost.c | 18 +++++++++++++-----
 drivers/vhost/vhost.h |  8 ++++++--
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f11bdbe4c2c5..f64efda48f21 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1633,17 +1633,25 @@ 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 1647b750169c..6f73f29d5979 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -85,13 +85,17 @@ 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 */
--
2.17.1