Re: [PATCH] vhost: Fix vhost_copy_to_user()

From: Jason Wang
Date: Wed Apr 11 2018 - 09:44:59 EST




On 2018å04æ11æ 21:30, Eric Auger wrote:
vhost_copy_to_user is used to copy vring used elements to userspace.
We should use VHOST_ADDR_USED instead of VHOST_ADDR_DESC.

Fixes: f88949138058 ("vhost: introduce O(1) vq metadata cache")
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>

---

This fixes a stall observed when running an aarch64 guest with
virtual smmu
---
drivers/vhost/vhost.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index bec722e..f44aead 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -744,7 +744,7 @@ static int vhost_copy_to_user(struct vhost_virtqueue *vq, void __user *to,
struct iov_iter t;
void __user *uaddr = vhost_vq_meta_fetch(vq,
(u64)(uintptr_t)to, size,
- VHOST_ADDR_DESC);
+ VHOST_ADDR_USED);
if (uaddr)
return __copy_to_user(uaddr, from, size);

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

Thanks!

Stable material I think.