virtio: add support for negotiating extended features

The virtio specifications allows for a device features space up
to 128 bits and more. Soon we are going to use some of the 'extended'
bits features for the virtio net driver.

Add support to allow extended features negotiation on a per
devices basis. Devices willing to negotiated extended features
need to implemented a new pair of features getter/setter, the
core will conditionally use them instead of the basic one.

Note that 'bad_features' don't need to be extended, as they are
bound to the 64 bits limit.

Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <9bb29d70adc3f2b8c7756d4e3cd076cffee87826.1758549625.git.pabeni@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index 11adfbf3abacd22ee2255627e54590607f9d3eb3..cef944e01588fd0a6de9230250a59cb554a579f9 100644 (file)
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -62,9 +62,14 @@ void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
     }
 
     /* Get the features of the plugged device. */
-    assert(vdc->get_features != NULL);
-    vdev->host_features = vdc->get_features(vdev, vdev->host_features,
-                                            &local_err);
+    if (vdc->get_features_ex) {
+        vdc->get_features_ex(vdev, vdev->host_features_ex, &local_err);
+    } else {
+        assert(vdc->get_features != NULL);
+        virtio_features_from_u64(vdev->host_features_ex,
+                                 vdc->get_features(vdev, vdev->host_features,
+                                                   &local_err));
+    }
     if (local_err) {
         error_propagate(errp, local_err);
         return;

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index bf53c211e5cc084237e4fbed562822f7fc49c0ac..34f977a3c9e969b8aa14c28c8b610e0fd6556956 100644 (file)
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3103,7 +3103,9 @@ static int virtio_set_features_nocheck(VirtIODevice *vdev, const uint64_t *val)
     bad = virtio_features_andnot(tmp, val, vdev->host_features_ex);
     virtio_features_and(tmp, val, vdev->host_features_ex);
 
-    if (k->set_features) {
+    if (k->set_features_ex) {
+        k->set_features_ex(vdev, val);
+    } else if (k->set_features) {
         bad = bad || virtio_features_use_ex(tmp);
         k->set_features(vdev, tmp[0]);
     }
@@ -3149,6 +3151,13 @@ virtio_set_features_nocheck_maybe_co(VirtIODevice *vdev,
 int virtio_set_features(VirtIODevice *vdev, uint64_t val)
 {
     uint64_t features[VIRTIO_FEATURES_NU64S];
+
+    virtio_features_from_u64(features, val);
+    return virtio_set_features_ex(vdev, features);
+}
+
+int virtio_set_features_ex(VirtIODevice *vdev, const uint64_t *features)
+{
     int ret;
     /*
      * The driver must not attempt to set features after feature negotiation
@@ -3158,13 +3167,12 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t val)
         return -EINVAL;
     }
 
-    if (val & (1ull << VIRTIO_F_BAD_FEATURE)) {
+    if (features[0] & (1ull << VIRTIO_F_BAD_FEATURE)) {
         qemu_log_mask(LOG_GUEST_ERROR,
                       "%s: guest driver for %s has enabled UNUSED(30) feature bit!\n",
                       __func__, vdev->name);
     }
 
-    virtio_features_from_u64(features, val);
     ret = virtio_set_features_nocheck(vdev, features);
     if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
         /* VIRTIO_RING_F_EVENT_IDX changes the size of the caches.  */

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 39e4059a66d3ed482f211c894574872c1cae2bc5..2aeb021fb3f1ec5aac698e893844d0d274e7bb12 100644 (file)
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -178,6 +178,9 @@ struct VirtioDeviceClass {
     /* This is what a VirtioDevice must implement */
     DeviceRealize realize;
     DeviceUnrealize unrealize;
+    void (*get_features_ex)(VirtIODevice *vdev, uint64_t *requested_features,
+                            Error **errp);
+    void (*set_features_ex)(VirtIODevice *vdev, const uint64_t *val);
     uint64_t (*get_features)(VirtIODevice *vdev,
                              uint64_t requested_features,
                              Error **errp);
@@ -373,6 +376,7 @@ void virtio_queue_reset(VirtIODevice *vdev, uint32_t queue_index);
 void virtio_queue_enable(VirtIODevice *vdev, uint32_t queue_index);
 void virtio_update_irq(VirtIODevice *vdev);
 int virtio_set_features(VirtIODevice *vdev, uint64_t val);
+int virtio_set_features_ex(VirtIODevice *vdev, const uint64_t *val);
 
 /* Base devices.  */
 typedef struct VirtIOBlkConf VirtIOBlkConf;