[PATCH V5 5/9] vhost: mark dirty pages during map uninit

Jason Wang
2019-08-09T05:49:21Z

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@redhat.com>
Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address")
Signed-off-by: Jason Wang <jasowang@redhat.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