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

[Jia Jia]

>
> 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@xxxxxxxxxx>
> >Signed-off-by: Jia Jia <physicalmtea@xxxxxxxxx>
> >---
> > 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

You're right, thanks for the reminder. That was my oversight—I should
have cleaned it up more carefully. I'll remember that going forward.

>
> >               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
> >
>