vringh: add 'iotlb_lock' to synchronize iotlb accesses

Usually iotlb accesses are synchronized with a spinlock.
Let's request it as a new parameter in vringh_set_iotlb() and
hold it when we navigate the iotlb in iotlb_translate() to avoid
race conditions with any new additions/deletions of ranges from
the ioltb.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-3-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 85d85faba058..f68122705719 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -1074,6 +1074,8 @@ static int iotlb_translate(const struct vringh *vrh,
 	int ret = 0;
 	u64 s = 0;
 
+	spin_lock(vrh->iotlb_lock);
+
 	while (len > s) {
 		u64 size, pa, pfn;
 
@@ -1103,6 +1105,8 @@ static int iotlb_translate(const struct vringh *vrh,
 		++ret;
 	}
 
+	spin_unlock(vrh->iotlb_lock);
+
 	return ret;
 }
 
@@ -1262,10 +1266,13 @@ EXPORT_SYMBOL(vringh_init_iotlb);
  * vringh_set_iotlb - initialize a vringh for a ring with IOTLB.
  * @vrh: the vring
  * @iotlb: iotlb associated with this vring
+ * @iotlb_lock: spinlock to synchronize the iotlb accesses
  */
-void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb)
+void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
+		      spinlock_t *iotlb_lock)
 {
 	vrh->iotlb = iotlb;
+	vrh->iotlb_lock = iotlb_lock;
 }
 EXPORT_SYMBOL(vringh_set_iotlb);