[dpdk-stable] [PATCH] vhost: retranslate vring addr when memory table changes

[Maxime Coquelin]

[ Backported from upstream commit d5022533c20aed365d513663806a999459037015 ]

When the vhost-user master sends memory updates using
VHOST_USER_SET_MEM request, the user backends unmap and then
mmap again the memory regions in its address space.

If the ring addresses have already been translated, it needs to
be translated again as they point to unmapped memory.

Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---

Hi Yongseok,

This patch is already in upstream master since v18.05, but wasn't
backported to stable because it initially fixed a bug in a new
feature.

I have been reported of a crash in the vhost-user library that
this patch fixes, so we would need to backport this patch to
v17.11 LTS.

Thanks,
Maxime

 lib/librte_vhost/vhost_user.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 07c848c7c..0eb5e0d65 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -623,8 +623,9 @@ vhost_memory_changed(struct VhostUserMemory *new,
 }
 
 static int
-vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
+vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *pmsg)
 {
+	struct virtio_net *dev = *pdev;
 	struct VhostUserMemory memory = pmsg->payload.memory;
 	struct rte_vhost_mem_region *reg;
 	void *mmap_addr;
@@ -748,6 +749,25 @@ vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
 			mmap_offset);
 	}
 
+	for (i = 0; i < dev->nr_vring; i++) {
+		struct vhost_virtqueue *vq = dev->virtqueue[i];
+
+		if (vq->desc || vq->avail || vq->used) {
+			/*
+			 * If the memory table got updated, the ring addresses
+			 * need to be translated again as virtual addresses have
+			 * changed.
+			 */
+			vring_invalidate(dev, vq);
+
+			dev = translate_ring_addresses(dev, i);
+			if (!dev)
+				return -1;
+
+			*pdev = dev;
+		}
+	}
+
 	dump_guest_pages(dev);
 
 	return 0;
@@ -1409,7 +1429,7 @@ vhost_user_msg_handler(int vid, int fd)
 		break;
 
 	case VHOST_USER_SET_MEM_TABLE:
-		ret = vhost_user_set_mem_table(dev, &msg);
+		ret = vhost_user_set_mem_table(&dev, &msg);
 		break;
 
 	case VHOST_USER_SET_LOG_BASE:
-- 
2.17.1