[PATCH v5 2/3] vhost/vsock: discard IOTLB when ACCESS_PLATFORM is cleared

[Jia Jia <physicalmtea@gmail.com>]

vhost_vsock_set_features() currently leaves the device IOTLB
attached when userspace clears VIRTIO_F_ACCESS_PLATFORM. Descriptor
translation can therefore continue to use mappings installed before the
feature change, including HVAs made stale by a later memory table update.

Use the common vhost helper when ACCESS_PLATFORM is absent. The helper
handles the no-IOTLB case internally, while the common initializer keeps
an existing IOTLB when ACCESS_PLATFORM remains enabled across a feature
update.

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 | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 1d8ec6bed53e..1a61d7db7605 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -849,10 +849,11 @@ 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)) {
 		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);