[PULL 01/31] virtio: check for validity of indirect descriptors

["Michael S. Tsirkin" <mst@redhat.com>]

From: Yuri Benditovich <yuri.benditovich@daynix.com>

virtio processes indirect descriptors even if the respected
feature VIRTIO_RING_F_INDIRECT_DESC was not negotiated.
If qemu is used with reduced set of features to emulate the
hardware device that does not support indirect descriptors,
the will probably trigger problematic flows on the hardware
setup but do not reveal the  mistake on qemu.
Add LOG_GUEST_ERROR for such case. This will issue logs with
'-d guest_errors' in the command line

Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Message-Id: <20250515063237.808293-1-yuri.benditovich@daynix.com>
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
---
 hw/virtio/virtio.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 2e98cecf64..5534251e01 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -205,6 +205,15 @@ static const char *virtio_id_to_name(uint16_t device_id)
     return name;
 }
 
+static void virtio_check_indirect_feature(VirtIODevice *vdev)
+{
+    if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "Device %s: indirect_desc was not negotiated!\n",
+                      vdev->name);
+    }
+}
+
 /* Called within call_rcu().  */
 static void virtio_free_region_cache(VRingMemoryRegionCaches *caches)
 {
@@ -1733,6 +1742,7 @@ static void *virtqueue_split_pop(VirtQueue *vq, size_t sz)
             virtio_error(vdev, "Invalid size for indirect buffer table");
             goto done;
         }
+        virtio_check_indirect_feature(vdev);
 
         /* loop over the indirect descriptor table */
         len = address_space_cache_init(&indirect_desc_cache, vdev->dma_as,
@@ -1870,6 +1880,7 @@ static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz)
             virtio_error(vdev, "Invalid size for indirect buffer table");
             goto done;
         }
+        virtio_check_indirect_feature(vdev);
 
         /* loop over the indirect descriptor table */
         len = address_space_cache_init(&indirect_desc_cache, vdev->dma_as,
-- 
MST