Jason Gunthorpe
2019-Jul-31 12:41 UTC
[PATCH V2 4/9] vhost: reset invalidate_count in vhost_set_vring_num_addr()
On Wed, Jul 31, 2019 at 04:46:50AM -0400, Jason Wang wrote:> The vhost_set_vring_num_addr() could be called in the middle of > invalidate_range_start() and invalidate_range_end(). If we don't reset > invalidate_count after the un-registering of MMU notifier, the > invalidate_cont will run out of sync (e.g never reach zero). This will > in fact disable the fast accessor path. Fixing by reset the count to > zero. > > Reported-by: Michael S. Tsirkin <mst at redhat.com>Did Michael report this as well?> Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address") > Signed-off-by: Jason Wang <jasowang at redhat.com> > drivers/vhost/vhost.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 2a3154976277..2a7217c33668 100644 > +++ b/drivers/vhost/vhost.c > @@ -2073,6 +2073,10 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d, > d->has_notifier = false; > } > > + /* reset invalidate_count in case we are in the middle of > + * invalidate_start() and invalidate_end(). > + */ > + vq->invalidate_count = 0; > vhost_uninit_vq_maps(vq); > #endif >
Jason Wang
2019-Jul-31 13:29 UTC
[PATCH V2 4/9] vhost: reset invalidate_count in vhost_set_vring_num_addr()
On 2019/7/31 ??8:41, Jason Gunthorpe wrote:> On Wed, Jul 31, 2019 at 04:46:50AM -0400, Jason Wang wrote: >> The vhost_set_vring_num_addr() could be called in the middle of >> invalidate_range_start() and invalidate_range_end(). If we don't reset >> invalidate_count after the un-registering of MMU notifier, the >> invalidate_cont will run out of sync (e.g never reach zero). This will >> in fact disable the fast accessor path. Fixing by reset the count to >> zero. >> >> Reported-by: Michael S. Tsirkin <mst at redhat.com> > Did Michael report this as well?Correct me if I was wrong. I think it's point 4 described in https://lkml.org/lkml/2019/7/21/25. Thanks> >> Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address") >> Signed-off-by: Jason Wang <jasowang at redhat.com> >> drivers/vhost/vhost.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >> index 2a3154976277..2a7217c33668 100644 >> +++ b/drivers/vhost/vhost.c >> @@ -2073,6 +2073,10 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d, >> d->has_notifier = false; >> } >> >> + /* reset invalidate_count in case we are in the middle of >> + * invalidate_start() and invalidate_end(). >> + */ >> + vq->invalidate_count = 0; >> vhost_uninit_vq_maps(vq); >> #endif >>
Jason Gunthorpe
2019-Jul-31 19:32 UTC
[PATCH V2 4/9] vhost: reset invalidate_count in vhost_set_vring_num_addr()
On Wed, Jul 31, 2019 at 09:29:28PM +0800, Jason Wang wrote:> > On 2019/7/31 ??8:41, Jason Gunthorpe wrote: > > On Wed, Jul 31, 2019 at 04:46:50AM -0400, Jason Wang wrote: > > > The vhost_set_vring_num_addr() could be called in the middle of > > > invalidate_range_start() and invalidate_range_end(). If we don't reset > > > invalidate_count after the un-registering of MMU notifier, the > > > invalidate_cont will run out of sync (e.g never reach zero). This will > > > in fact disable the fast accessor path. Fixing by reset the count to > > > zero. > > > > > > Reported-by: Michael S. Tsirkin <mst at redhat.com> > > Did Michael report this as well? > > > Correct me if I was wrong. I think it's point 4 described in > https://lkml.org/lkml/2019/7/21/25.I'm not sure what that is talking about But this fixes what I described: https://lkml.org/lkml/2019/7/22/554 Jason