virtio: list legacy-capable devices

Several types of virtio devices had already been around before the
virtio standard was specified. These devices support virtio in legacy
(and transitional) mode.

Devices that have been added in the virtio standard are considered
non-transitional (i.e. with no support for legacy virtio).

Provide a helper function so virtio transports can figure that out
easily.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200707105446.677966-2-cohuck@redhat.com>
Cc: qemu-stable@nongnu.org
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 5bd2a2f6217dffc2a5f4bbe990c1c6705364fa23..546a198e79b078948ffffcb6d36aea3c65d05c7e 100644 (file)
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -27,6 +27,7 @@
 #include "hw/virtio/virtio-access.h"
 #include "sysemu/dma.h"
 #include "sysemu/runstate.h"
+#include "standard-headers/linux/virtio_ids.h"
 
 /*
  * The alignment to use between consumer and producer parts of vring.
@@ -3279,6 +3280,30 @@ void virtio_init(VirtIODevice *vdev, const char *name,
     vdev->use_guest_notifier_mask = true;
 }
 
+/*
+ * Only devices that have already been around prior to defining the virtio
+ * standard support legacy mode; this includes devices not specified in the
+ * standard. All newer devices conform to the virtio standard only.
+ */
+bool virtio_legacy_allowed(VirtIODevice *vdev)
+{
+    switch (vdev->device_id) {
+    case VIRTIO_ID_NET:
+    case VIRTIO_ID_BLOCK:
+    case VIRTIO_ID_CONSOLE:
+    case VIRTIO_ID_RNG:
+    case VIRTIO_ID_BALLOON:
+    case VIRTIO_ID_RPMSG:
+    case VIRTIO_ID_SCSI:
+    case VIRTIO_ID_9P:
+    case VIRTIO_ID_RPROC_SERIAL:
+    case VIRTIO_ID_CAIF:
+        return true;
+    default:
+        return false;
+    }
+}
+
 hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
 {
     return vdev->vq[n].vring.desc;

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index b69d517496358d4dcba30eeb42c721e866798051..198ffc762678647cc9275c376be821cdb28e440a 100644 (file)
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -396,4 +396,6 @@ static inline bool virtio_device_disabled(VirtIODevice *vdev)
     return unlikely(vdev->disabled || vdev->broken);
 }
 
+bool virtio_legacy_allowed(VirtIODevice *vdev);
+
 #endif