Eric Auger
2023-Aug-23 15:30 UTC
[PATCH] vhost: Allow null msg.size on VHOST_IOTLB_INVALIDATE
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 at redhat.com>
Fixes: e2ae38cf3d91 ("vhost: fix hung thread due to erroneous iotlb
entries")
---
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;
}
--
2.41.0
Jason Wang
2023-Aug-24 03:23 UTC
[PATCH] vhost: Allow null msg.size on VHOST_IOTLB_INVALIDATE
On Wed, Aug 23, 2023 at 11:30?PM Eric Auger <eric.auger at redhat.com> 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 at redhat.com>Cc: stable at vger.kernel.org I think we need to document the usage of 0 as msg.size for IOTLB_INVALIDATE in uapi. Other than this: Acked-by: Jason Wang <jasowang at redhat.com> Thanks> Fixes: e2ae38cf3d91 ("vhost: fix hung thread due to erroneous iotlb entries") > --- > 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; > } > -- > 2.41.0 >