virtio_balloon: disable VIOMMU support

commit e41b1355508debe45fda33ef8c03ff3ba5d206b9 upstream.

virtio balloon bypasses the DMA API entirely so does not support the
VIOMMU right now.  It's not clear we need that support, for now let's
just make sure we don't pretend to support it.

Cc: Wei Wang <wei.w.wang@intel.com>
Fixes: 1a937693993f ("virtio: new feature to detect IOMMU device quirk")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 34adf9b9c0538815db33f62ed842de49be5222e7..b7f1fda40422fbaf871b968db80dc43d6d4ea9e0 100644 (file)
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -664,6 +664,12 @@ static int virtballoon_restore(struct virtio_device *vdev)
 }
 #endif
 
+static int virtballoon_validate(struct virtio_device *vdev)
+{
+       __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
+       return 0;
+}
+
 static unsigned int features[] = {
        VIRTIO_BALLOON_F_MUST_TELL_HOST,
        VIRTIO_BALLOON_F_STATS_VQ,
@@ -676,6 +682,7 @@ static struct virtio_driver virtio_balloon_driver = {
        .driver.name =  KBUILD_MODNAME,
        .driver.owner = THIS_MODULE,
        .id_table =     id_table,
+       .validate =     virtballoon_validate,
        .probe =        virtballoon_probe,
        .remove =       virtballoon_remove,
        .config_changed = virtballoon_changed,