netdev - [PATCH V4 5/9] vhost: mark dirty pages during map uninit

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Message-Id: <20190807070617.23716-6-jasowang@redhat.com>
Date:   Wed,  7 Aug 2019 03:06:13 -0400
From:   Jason Wang <jasowang@...hat.com>
To:     mst@...hat.com, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org, jgg@...pe.ca,
        Jason Wang <jasowang@...hat.com>
Subject: [PATCH V4 5/9] vhost: mark dirty pages during map uninit

We don't mark dirty pages if the map was teared down outside MMU
notifier. This will lead untracked dirty pages. Fixing by marking
dirty pages during map uninit.

Reported-by: Michael S. Tsirkin <mst@...hat.com>
Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address")
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
 drivers/vhost/vhost.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 2a7217c33668..c12cdadb0855 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -305,6 +305,18 @@ static void vhost_map_unprefetch(struct vhost_map *map)
 	kfree(map);
 }
 
+static void vhost_set_map_dirty(struct vhost_virtqueue *vq,
+				struct vhost_map *map, int index)
+{
+	struct vhost_uaddr *uaddr = &vq->uaddrs[index];
+	int i;
+
+	if (uaddr->write) {
+		for (i = 0; i < map->npages; i++)
+			set_page_dirty(map->pages[i]);
+	}
+}
+
 static void vhost_uninit_vq_maps(struct vhost_virtqueue *vq)
 {
 	struct vhost_map *map[VHOST_NUM_ADDRS];
@@ -314,8 +326,10 @@ static void vhost_uninit_vq_maps(struct vhost_virtqueue *vq)
 	for (i = 0; i < VHOST_NUM_ADDRS; i++) {
 		map[i] = rcu_dereference_protected(vq->maps[i],
 				  lockdep_is_held(&vq->mmu_lock));
-		if (map[i])
+		if (map[i]) {
+			vhost_set_map_dirty(vq, map[i], i);
 			rcu_assign_pointer(vq->maps[i], NULL);
+		}
 	}
 	spin_unlock(&vq->mmu_lock);
 
@@ -353,7 +367,6 @@ static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
 {
 	struct vhost_uaddr *uaddr = &vq->uaddrs[index];
 	struct vhost_map *map;
-	int i;
 
 	if (!vhost_map_range_overlap(uaddr, start, end))
 		return;
@@ -364,10 +377,7 @@ static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
 	map = rcu_dereference_protected(vq->maps[index],
 					lockdep_is_held(&vq->mmu_lock));
 	if (map) {
-		if (uaddr->write) {
-			for (i = 0; i < map->npages; i++)
-				set_page_dirty(map->pages[i]);
-		}
+		vhost_set_map_dirty(vq, map, index);
 		rcu_assign_pointer(vq->maps[index], NULL);
 	}
 	spin_unlock(&vq->mmu_lock);
-- 
2.18.1