[PATCH] vhost: disable all features and trace last_avail_idx

[Eugenio PÃrez]

---
 drivers/vhost/vhost.c | 13 +++++++++++--
 drivers/vhost/vhost.h | 10 +++++-----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index fc422c3e5c08..021d70bed015 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1645,6 +1645,9 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
 		vq->last_avail_idx = s.num;
 		/* Forget the cached index value. */
 		vq->avail_idx = vq->last_avail_idx;
+		pr_debug(
+			"VHOST_SET_VRING_BASE [vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u]",
+			vq, vq->last_avail_idx, vq->avail_idx);
 		break;
 	case VHOST_GET_VRING_BASE:
 		s.index = idx;
@@ -2239,8 +2242,8 @@ static int fetch_buf(struct vhost_virtqueue *vq)
 		vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
 
 		if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
-			vq_err(vq, "Guest moved used index from %u to %u",
-				last_avail_idx, vq->avail_idx);
+			vq_err(vq, "Guest moved vq %p used index from %u to %u",
+				vq, last_avail_idx, vq->avail_idx);
 			return -EFAULT;
 		}
 
@@ -2316,6 +2319,9 @@ static int fetch_buf(struct vhost_virtqueue *vq)
 	BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
 
 	/* On success, increment avail index. */
+	pr_debug(
+		"[vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u][vq->ndescs=%d][vq->first_desc=%d]",
+		vq, vq->last_avail_idx, vq->avail_idx, vq->ndescs, vq->first_desc);
 	vq->last_avail_idx++;
 
 	return 0;
@@ -2431,6 +2437,9 @@ EXPORT_SYMBOL_GPL(vhost_get_vq_desc);
 /* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
 void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
 {
+	pr_debug(
+		"DISCARD [vq=%p][vq->last_avail_idx=%u][vq->avail_idx=%u][n=%d]",
+		vq, vq->last_avail_idx, vq->avail_idx, n);
 	vq->last_avail_idx -= n;
 }
 EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 661088ae6dc7..08f6d2ccb697 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -250,11 +250,11 @@ int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled);
 	} while (0)
 
 enum {
-	VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
-			 (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
-			 (1ULL << VIRTIO_RING_F_EVENT_IDX) |
-			 (1ULL << VHOST_F_LOG_ALL) |
-			 (1ULL << VIRTIO_F_ANY_LAYOUT) |
+	VHOST_FEATURES = /* (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | */
+			 /* (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | */
+			 /* (1ULL << VIRTIO_RING_F_EVENT_IDX) | */
+			 /* (1ULL << VHOST_F_LOG_ALL) | */
+			 /* (1ULL << VIRTIO_F_ANY_LAYOUT) | */
 			 (1ULL << VIRTIO_F_VERSION_1)
 };
 
-- 
2.18.1