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Date: Fri, 9 Aug 2019 01:48:46 -0400 From: Jason Wang <jasowang@...hat.com> To: mst@...hat.com, kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Cc: linux-mm@...ck.org, jgg@...pe.ca, Jason Wang <jasowang@...hat.com> Subject: [PATCH V5 4/9] vhost: reset invalidate_count in vhost_set_vring_num_addr() 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@...hat.com> Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address") Signed-off-by: Jason Wang <jasowang@...hat.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 --- a/drivers/vhost/vhost.c +++ 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 -- 2.18.1
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