This is a follow-up to Micheal's patch [1] and the discussion with Halil and
Jason [2].
I made two patches, one to fix the problem and one for cleanup. This should
simplify the backport of the fix because we've had the problem since
vhost-vsock was introduced (v4.8) and that part has been touched a bit
recently.
Thanks,
Stefano
[1] https://lore.kernel.org/virtualization/20211122105822.onarsa4sydzxqynu@steredhat/T/#t
[2] https://lore.kernel.org/virtualization/[email protected]/T/#t
Stefano Garzarella (2):
vhost/vsock: fix incorrect used length reported to the guest
vhost/vsock: cleanup removing `len` variable
drivers/vhost/vsock.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
--
2.31.1
The "used length" reported by calling vhost_add_used() must be the
number of bytes written by the device (using "in" buffers).
In vhost_vsock_handle_tx_kick() the device only reads the guest
buffers (they are all "out" buffers), without writing anything,
so we must pass 0 as "used length" to comply virtio spec.
Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko")
Cc: [email protected]
Reported-by: Halil Pasic <[email protected]>
Suggested-by: Jason Wang <[email protected]>
Signed-off-by: Stefano Garzarella <[email protected]>
---
drivers/vhost/vsock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 938aefbc75ec..4e3b95af7ee4 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -554,7 +554,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
virtio_transport_free_pkt(pkt);
len += sizeof(pkt->hdr);
- vhost_add_used(vq, head, len);
+ vhost_add_used(vq, head, 0);
total_len += len;
added = true;
} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
--
2.31.1
We can increment `total_len` directly and remove `len` since it
is no longer used for vhost_add_used().
Signed-off-by: Stefano Garzarella <[email protected]>
---
drivers/vhost/vsock.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 4e3b95af7ee4..d6ca1c7ad513 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -511,8 +511,6 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
vhost_disable_notify(&vsock->dev, vq);
do {
- u32 len;
-
if (!vhost_vsock_more_replies(vsock)) {
/* Stop tx until the device processes already
* pending replies. Leave tx virtqueue
@@ -540,7 +538,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
continue;
}
- len = pkt->len;
+ total_len += sizeof(pkt->hdr) + pkt->len;
/* Deliver to monitoring devices all received packets */
virtio_transport_deliver_tap_pkt(pkt);
@@ -553,9 +551,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
else
virtio_transport_free_pkt(pkt);
- len += sizeof(pkt->hdr);
vhost_add_used(vq, head, 0);
- total_len += len;
added = true;
} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
--
2.31.1
On Mon, Nov 22, 2021 at 05:35:23PM +0100, Stefano Garzarella wrote:
> This is a follow-up to Micheal's patch [1] and the discussion with Halil and
> Jason [2].
>
> I made two patches, one to fix the problem and one for cleanup. This should
> simplify the backport of the fix because we've had the problem since
> vhost-vsock was introduced (v4.8) and that part has been touched a bit
> recently.
>
> Thanks,
> Stefano
>
> [1] https://lore.kernel.org/virtualization/20211122105822.onarsa4sydzxqynu@steredhat/T/#t
> [2] https://lore.kernel.org/virtualization/[email protected]/T/#t
>
> Stefano Garzarella (2):
> vhost/vsock: fix incorrect used length reported to the guest
> vhost/vsock: cleanup removing `len` variable
>
> drivers/vhost/vsock.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> --
> 2.31.1
>
Reviewed-by: Stefan Hajnoczi <[email protected]>
On Mon, 22 Nov 2021 17:35:24 +0100
Stefano Garzarella <[email protected]> wrote:
> The "used length" reported by calling vhost_add_used() must be the
> number of bytes written by the device (using "in" buffers).
>
> In vhost_vsock_handle_tx_kick() the device only reads the guest
> buffers (they are all "out" buffers), without writing anything,
> so we must pass 0 as "used length" to comply virtio spec.
>
> Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko")
> Cc: [email protected]
> Reported-by: Halil Pasic <[email protected]>
> Suggested-by: Jason Wang <[email protected]>
> Signed-off-by: Stefano Garzarella <[email protected]>
Reviewed-by: Halil Pasic <[email protected]>
> ---
> drivers/vhost/vsock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 938aefbc75ec..4e3b95af7ee4 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -554,7 +554,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> virtio_transport_free_pkt(pkt);
>
> len += sizeof(pkt->hdr);
> - vhost_add_used(vq, head, len);
> + vhost_add_used(vq, head, 0);
> total_len += len;
> added = true;
> } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));