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

vhost_net_set_features() leaves the device IOTLB attached when
userspace clears VIRTIO_F_ACCESS_PLATFORM. Later descriptor translation
can therefore continue to use translations from the old IOTLB after the
userspace memory table has changed.

Use the common vhost helper when ACCESS_PLATFORM is absent. The helper
handles the no-IOTLB case internally, while the common initializer also
keeps an existing IOTLB when a feature update retains ACCESS_PLATFORM, so
logging updates do not discard valid translations.

Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API")
Link: https://lore.kernel.org/all/20260726141158.1652386-1-physicalmtea@gmail.com/ (local)
Signed-off-by: Jia Jia <redacted>
---
 drivers/vhost/net.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index c6536cad9c4f..8d6f530f49b3 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c

@@ -1687,7 +1687,8 @@ static int vhost_net_set_features(struct vhost_net *n, const u64 *features)
 	if (virtio_features_test_bit(features, VIRTIO_F_ACCESS_PLATFORM)) {
 		if (vhost_init_device_iotlb(&n->dev))
 			goto out_unlock;
-	}
+	} else
+		vhost_clear_device_iotlb(&n->dev);
 
 	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 		mutex_lock(&n->vqs[i].vq.mutex);