[PATCH v2] IOMMU not supported by vhost-user.

[lagarcia@linux.ibm.com]

From: Leonardo Garcia <lagarcia@br.ibm.com>

Currently, as IOMMU is not supported, if a user mistakenly set it and
tries to mount the vhost-user filesystem (or use any other vhost-user
based device) inside the guest, whenever the user tries to access the
device, the system will hang forever (because virtiofsd will not be
running anymore).

Signed-off-by: Leonardo Garcia <lagarcia@br.ibm.com>
---
 hw/virtio/vhost-user-fs.c | 5 +++++
 hw/virtio/vhost-user.c    | 7 +++++++
 hw/virtio/vhost.c         | 1 -
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index ac4fc34b36..059b0d2ef9 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -222,6 +222,11 @@ static void vuf_device_realize(DeviceState *dev, Error **errp)
     /* 1 high prio queue, plus the number configured */
     fs->vhost_dev.nvqs = 1 + fs->conf.num_request_queues;
     fs->vhost_dev.vqs = g_new0(struct vhost_virtqueue, fs->vhost_dev.nvqs);
+    /*
+     * vhost_user_backend_init does additional checks if VirtIODevice is defined
+     * in vhost_dev
+     */
+    fs->vhost_dev.vdev = vdev;
     ret = vhost_dev_init(&fs->vhost_dev, &fs->vhost_user,
                          VHOST_BACKEND_TYPE_USER, 0);
     if (ret < 0) {
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 2fdd5daf74..6ab760364b 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1849,6 +1849,13 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque)
             }
         }
 
+        if ((dev->vdev != NULL) &&
+            virtio_host_has_feature(dev->vdev, VIRTIO_F_IOMMU_PLATFORM) &&
+            !(features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
+            error_report("IOMMU is currently not supported with vhost-user");
+            return -1;
+        }
+
         if (virtio_has_feature(features, VIRTIO_F_IOMMU_PLATFORM) &&
                 !(virtio_has_feature(dev->protocol_features,
                     VHOST_USER_PROTOCOL_F_SLAVE_REQ) &&
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 6e17d631f7..78e58d2148 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1293,7 +1293,6 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     int i, r, n_initialized_vqs = 0;
     Error *local_err = NULL;
 
-    hdev->vdev = NULL;
     hdev->migration_blocker = NULL;
 
     r = vhost_set_backend_type(hdev, backend_type);
-- 
2.29.2