Re: [PATCH v3 2/2] vhost/vsock: keep IOTLB across feature updates

[Stefano Garzarella <sgarzare@redhat.com>]

On Mon, Aug 10, 2026 at 09:40:18PM +0800, Jia Jia wrote:
>VHOST_SET_FEATURES is also used to update logging while a device is
>running. When ACCESS_PLATFORM stays enabled, allocating a new empty
>IOTLB on every call drops valid translations and forces avoidable
>misses.
>
>Initialize the device IOTLB only when one does not already exist.
>

Do we need a Fixes tag here?

>Signed-off-by: Jia Jia <physicalmtea@gmail.com>
>---
> drivers/vhost/vsock.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 7372c22691de..1beae7f5b9a9 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -889,7 +889,8 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
> 		goto err;
> 	}
>
>-	if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
>+	if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)) &&
>+	    !vsock->dev.iotlb) {

Do we need to do the same in vhost-net too?

Thanks,
Stefano

> 		if (vhost_init_device_iotlb(&vsock->dev))
> 			goto err;
> 	}
>-- 
>2.34.1
>