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Message-Id: <20190723075718.6275-5-jasowang@redhat.com>
Date: Tue, 23 Jul 2019 03:57:16 -0400
From: Jason Wang <jasowang@...hat.com>
To: mst@...hat.com, jasowang@...hat.com
Cc: kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] 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 03666b702498..89c9f08b5146 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2074,6 +2074,10 @@ 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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