Re: [PATCH v7 2/3] vhost/vsock: discard IOTLB when ACCESS_PLATFORM is cleared

[Stefano Garzarella <sgarzare@redhat.com>]

On Thu, Aug 20, 2026 at 04:03:31PM +0800, Jia Jia wrote:
>Clear the device IOTLB when userspace clears VIRTIO_F_ACCESS_PLATFORM.
>Otherwise descriptor translation can continue to use mappings installed
>before the feature change.
>
>The common helper invalidates cached vring access and applies the
>transition even while a backend is attached. The backend remains attached,
>but userspace must configure the vring addresses for the new address mode
>after a successful live transition.
>
>Fixes: e13a6915a03f ("vhost/vsock: add IOTLB API support")
>Suggested-by: Michael S. Tsirkin <mst@redhat.com>
>Signed-off-by: Jia Jia <physicalmtea@gmail.com>
>---
> drivers/vhost/vsock.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 9aaab6bb8061..e1e9d002d6ae 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -865,9 +865,11 @@ 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)) {

Unrelated change...

I think I've already pointed something like this in previous versions: 
for a patch that fixes a specific issue, these unrelated changes should 
be avoided. Please keep this in mind.

Stefano

> 		if (vhost_init_device_iotlb(&vsock->dev))
> 			goto err;
>+	} else {
>+		vhost_clear_device_iotlb(&vsock->dev);
> 	}
>
> 	vsock->seqpacket_allow = features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET);
>-- 
>2.34.1
>