[PATCH v3 for 9.1 3/6] virtio-mmio: Handle extra notification data

[Jonah Palmer]

Add support to virtio-mmio devices for handling the extra data sent from
the driver to the device when the VIRTIO_F_NOTIFICATION_DATA transport
feature has been negotiated.

The extra data that's passed to the virtio-mmio device when this feature
is enabled varies depending on the device's virtqueue layout.

The data passed to the virtio-mmio device is in the same format as the
data passed to virtio-pci devices.

Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
---
 hw/virtio/virtio-mmio.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 22f9fbcf5a..003c363f0b 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -248,6 +248,7 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, 
uint64_t value,
 {
     VirtIOMMIOProxy *proxy = (VirtIOMMIOProxy *)opaque;
     VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+    uint16_t vq_idx;
 
     trace_virtio_mmio_write_offset(offset, value);
 
@@ -407,8 +408,13 @@ static void virtio_mmio_write(void *opaque, hwaddr offset, 
uint64_t value,
         }
         break;
     case VIRTIO_MMIO_QUEUE_NOTIFY:
-        if (value < VIRTIO_QUEUE_MAX) {
-            virtio_queue_notify(vdev, value);
+        vq_idx = value;
+        if (vq_idx < VIRTIO_QUEUE_MAX && virtio_queue_get_num(vdev, vq_idx)) {
+            if (virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
+                virtio_queue_set_shadow_avail_idx(virtio_get_queue(vdev, 
vq_idx),
+                                                  (value >> 16) & 0xFFFF);
+            }
+            virtio_queue_notify(vdev, vq_idx);
         }
         break;
     case VIRTIO_MMIO_INTERRUPT_ACK:
-- 
2.39.3