virtio-pci-modern: introduce helpers for setting and getting features

This patch introduces helpers for setting and getting features.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210104065503.199631-8-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_pci_modern.c

@@ -137,12 +137,16 @@ static void __iomem *map_capability(struct pci_dev *dev, int off,
 	return p;
 }
 
-/* virtio config->get_features() implementation */
-static u64 vp_get_features(struct virtio_device *vdev)
+/*
+ * vp_modern_get_features - get features from device
+ * @mdev: the modern virtio-pci device
+ *
+ * Returns the features read from the device
+ */
+static u64 vp_modern_get_features(struct virtio_pci_modern_device *mdev)
 {
-	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
 	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
 	u64 features;
 
 	vp_iowrite32(0, &cfg->device_feature_select);
@@ -153,6 +157,14 @@ static u64 vp_get_features(struct virtio_device *vdev)
 	return features;
 }
 
+/* virtio config->get_features() implementation */
+static u64 vp_get_features(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	return vp_modern_get_features(&vp_dev->mdev);
+}
+
 static void vp_transport_features(struct virtio_device *vdev, u64 features)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
@@ -163,12 +175,26 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
 		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
 }
 
+/*
+ * vp_modern_set_features - set features to device
+ * @mdev: the modern virtio-pci device
+ * @features: the features set to device
+ */
+static void vp_modern_set_features(struct virtio_pci_modern_device *mdev,
+				   u64 features)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite32(0, &cfg->guest_feature_select);
+	vp_iowrite32((u32)features, &cfg->guest_feature);
+	vp_iowrite32(1, &cfg->guest_feature_select);
+	vp_iowrite32(features >> 32, &cfg->guest_feature);
+}
+
 /* virtio config->finalize_features() implementation */
 static int vp_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
 	u64 features = vdev->features;
 
 	/* Give virtio_ring a chance to accept features. */
@@ -183,10 +209,7 @@ static int vp_finalize_features(struct virtio_device *vdev)
 		return -EINVAL;
 	}
 
-	vp_iowrite32(0, &cfg->guest_feature_select);
-	vp_iowrite32((u32)vdev->features, &cfg->guest_feature);
-	vp_iowrite32(1, &cfg->guest_feature_select);
-	vp_iowrite32(vdev->features >> 32, &cfg->guest_feature);
+	vp_modern_set_features(&vp_dev->mdev, vdev->features);
 
 	return 0;
 }