[dpdk-dev] [PATCH 2/3] vhost: fix vring addr handling during live migration

[Tiwei Bie <tiwei.bie@intel.com>]

When live migration starts, QEMU will set ring addrs again for
each virtqueue. In this case, we should try to translate ring
addrs after we invalidating the ring, otherwise virtqueues can
be enabled with the addrs untranslated. Besides, also leverage
the access_ok flag in non-IOMMU case to prevent the data path
accessing invalidated virtqueues.

Fixes: 5a4933e56be4 ("vhost: postpone ring address translations at kick time only")
Cc: stable@dpdk.org

Reported-by: Yilong Lv <lvyilong.lyl@alibaba-inc.com>
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
 lib/librte_vhost/vhost.c      |  3 +--
 lib/librte_vhost/vhost_user.c | 12 ++++++++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 981837b5d..77be16069 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -358,7 +358,7 @@ vring_translate(struct virtio_net *dev, struct vhost_virtqueue *vq)
 {
 
 	if (!(dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
-		goto out;
+		return -1;
 
 	if (vq_is_packed(dev)) {
 		if (vring_translate_packed(dev, vq) < 0)
@@ -367,7 +367,6 @@ vring_translate(struct virtio_net *dev, struct vhost_virtqueue *vq)
 		if (vring_translate_split(dev, vq) < 0)
 			return -1;
 	}
-out:
 	vq->access_ok = 1;
 
 	return 0;
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index ea43ab139..381250cbc 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -622,6 +622,7 @@ translate_ring_addresses(struct virtio_net *dev, int vq_index)
 			return dev;
 		}
 
+		vq->access_ok = 1;
 		return dev;
 	}
 
@@ -680,6 +681,7 @@ translate_ring_addresses(struct virtio_net *dev, int vq_index)
 	}
 
 	vq->log_guest_addr = addr->log_guest_addr;
+	vq->access_ok = 1;
 
 	VHOST_LOG_DEBUG(VHOST_CONFIG, "(%d) mapped address desc: %p\n",
 			dev->vid, vq->desc);
@@ -704,6 +706,7 @@ vhost_user_set_vring_addr(struct virtio_net **pdev, struct VhostUserMsg *msg,
 	struct virtio_net *dev = *pdev;
 	struct vhost_virtqueue *vq;
 	struct vhost_vring_addr *addr = &msg->payload.addr;
+	bool access_ok;
 
 	if (dev->mem == NULL)
 		return RTE_VHOST_MSG_RESULT_ERR;
@@ -711,6 +714,8 @@ vhost_user_set_vring_addr(struct virtio_net **pdev, struct VhostUserMsg *msg,
 	/* addr->index refers to the queue index. The txq 1, rxq is 0. */
 	vq = dev->virtqueue[msg->payload.addr.index];
 
+	access_ok = vq->access_ok;
+
 	/*
 	 * Rings addresses should not be interpreted as long as the ring is not
 	 * started and enabled
@@ -719,8 +724,9 @@ vhost_user_set_vring_addr(struct virtio_net **pdev, struct VhostUserMsg *msg,
 
 	vring_invalidate(dev, vq);
 
-	if (vq->enabled && (dev->features &
-				(1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
+	if ((vq->enabled && (dev->features &
+				(1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) ||
+			access_ok) {
 		dev = translate_ring_addresses(dev, msg->payload.addr.index);
 		if (!dev)
 			return RTE_VHOST_MSG_RESULT_ERR;
@@ -1325,6 +1331,8 @@ vhost_user_get_vring_base(struct virtio_net **pdev,
 	msg->size = sizeof(msg->payload.state);
 	msg->fd_num = 0;
 
+	vring_invalidate(dev, vq);
+
 	return RTE_VHOST_MSG_RESULT_REPLY;
 }
 
-- 
2.17.1