Hi,

On 9/27/23 16:05, Eric Auger wrote:

Commit e2ae38cf3d91 ("vhost: fix hung thread due to erroneous iotlb entries") Forbade vhost iotlb msg with null size to prevent entries with size = start = 0 and last = ULONG_MAX to end up in the iotlb.

Then commit 95932ab2ea07 ("vhost: allow batching hint without size") only applied the check for VHOST_IOTLB_UPDATE and VHOST_IOTLB_INVALIDATE message types to fix a regression observed with batching hit.

Still, the introduction of that check introduced a regression for some users attempting to invalidate the whole ULONG_MAX range by setting the size to 0. This is the case with qemu/smmuv3/vhost integration which does not work anymore. It Looks safe to partially revert the original commit and allow VHOST_IOTLB_INVALIDATE messages with null size. vhost_iotlb_del_range() will compute a correct end iova. Same for vhost_vdpa_iotlb_unmap().

Signed-off-by: Eric Auger eric.auger@redhat.com Fixes: e2ae38cf3d91 ("vhost: fix hung thread due to erroneous iotlb entries") Cc: stable@vger.kernel.org # v5.17+ Acked-by: Jason Wang jasowang@redhat.com

Gentle Ping.

Thanks

Eric

---

drivers/vhost/vhost.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c71d573f1c94..e0c181ad17e3 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1458,9 +1458,7 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev, goto done; }

• if ((msg.type == VHOST_IOTLB_UPDATE ||

•     msg.type == VHOST_IOTLB_INVALIDATE) &&
  

•     msg.size == 0) {
  

• if (msg.type == VHOST_IOTLB_UPDATE && msg.size == 0) { ret = -EINVAL; goto done; }