virtio: feature bit manipulation helpers

Add virtio_{add,clear}_feature helper functions for manipulating a
feature bits variable. This has some benefits over open coding:
- add check that the bit is in a sane range
- make it obvious at a glance what is going on
- have a central point to change when we want to extend feature bits

Convert existing code manipulating features to use the new helpers.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 3 insertions, 3 deletions

diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 2450c13747..10123f34b2 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -349,7 +349,7 @@ static void virtio_mmio_device_plugged(DeviceState *opaque)
 {
     VirtIOMMIOProxy *proxy = VIRTIO_MMIO(opaque);
 
-    proxy->host_features |= (0x1 << VIRTIO_F_NOTIFY_ON_EMPTY);
+    virtio_add_feature(&proxy->host_features, VIRTIO_F_NOTIFY_ON_EMPTY);
     proxy->host_features = virtio_bus_get_vdev_features(&proxy->bus,
                                                         proxy->host_features);
 }
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 927997680e..6dd41b992f 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -952,8 +952,8 @@ static void virtio_pci_device_plugged(DeviceState *d)
         proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
     }
 
-    proxy->host_features |= 0x1 << VIRTIO_F_NOTIFY_ON_EMPTY;
-    proxy->host_features |= 0x1 << VIRTIO_F_BAD_FEATURE;
+    virtio_add_feature(&proxy->host_features, VIRTIO_F_NOTIFY_ON_EMPTY);
+    virtio_add_feature(&proxy->host_features, VIRTIO_F_BAD_FEATURE);
     proxy->host_features = virtio_bus_get_vdev_features(bus,
                                                       proxy->host_features);
 }