FAILED: patch "[PATCH] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()" failed to apply to 4.9-stable tree

FAILED: patch "[PATCH] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()" failed to apply to 4.9-stable tree

[gregkh]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 71878fa46c7e3b40fa7b3f1b6e4ba3f92f1ac359 Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Sat, 3 Oct 2020 12:02:03 +0200
Subject: [PATCH] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()

The open-coded computation of the used size doesn't take the event
into account when the VIRTIO_RING_F_EVENT_IDX feature is present.
Fix that by using vhost_get_used_size().

Fixes: 8ea8cf89e19a ("vhost: support event index")
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kurz <groug@kaod.org>
Link: https://lore.kernel.org/r/160171932300.284610.11846106312938909461.stgit@bahia.lan
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index c3b49975dc28..9d2c225fb518 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1519,8 +1519,7 @@ static long vhost_vring_set_addr(struct vhost_dev *d,
 		/* Also validate log access for used ring if enabled. */
 		if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
 			!log_access_ok(vq->log_base, a.log_guest_addr,
-				sizeof *vq->used +
-				vq->num * sizeof *vq->used->ring))
+				       vhost_get_used_size(vq, vq->num)))
 			return -EINVAL;
 	}