From ad7aa686d172c8ba0beb975cdb9df986eec043ac Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Thu, 10 Mar 2022 15:52:11 +0800
Subject: [PATCH] vhost: allow batching hint without size
commit 95932ab2ea07b79cdb33121e2f40ccda9e6a73b5 upstream.
Commit e2ae38cf3d91 ("vhost: fix hung thread due to erroneous iotlb
entries") tries to reject the IOTLB message whose size is zero. But
the size is not necessarily meaningful, one example is the batching
hint, so the commit breaks that.
Fixing this be reject zero size message only if the message is used to
update/invalidate the IOTLB.
Fixes: e2ae38cf3d91 ("vhost: fix hung thread due to erroneous iotlb entries")
Reported-by: Eli Cohen <elic@nvidia.com>
Cc: Anirudh Rayabharam <mail@anirudhrb.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220310075211.4801-1-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vhost/vhost.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 55475fd59fb7c..6942472cffb0f 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1170,7 +1170,9 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
goto done;
}
- if (msg.size == 0) {
+ if ((msg.type == VHOST_IOTLB_UPDATE ||
+ msg.type == VHOST_IOTLB_INVALIDATE) &&
+ msg.size == 0) {
ret = -EINVAL;
goto done;
}