virtio-pci-modern: introduce helper for setting/geting queue size

This patch introduces helper for setting/getting queue size for modern
device.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210104065503.199631-13-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_pci_modern.c

@@ -262,6 +262,36 @@ static bool vp_modern_get_queue_enable(struct virtio_pci_modern_device *mdev,
 	return vp_ioread16(&mdev->common->queue_enable);
 }
 
+/*
+ * vp_modern_set_queue_size - set size for a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ * @size: the size of the virtqueue
+ */
+static void vp_modern_set_queue_size(struct virtio_pci_modern_device *mdev,
+				     u16 index, u16 size)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+	vp_iowrite16(size, &mdev->common->queue_size);
+
+}
+
+/*
+ * vp_modern_get_queue_size - get size for a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ *
+ * Returns the size of the virtqueue
+ */
+static u16 vp_modern_get_queue_size(struct virtio_pci_modern_device *mdev,
+				    u16 index)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+
+	return vp_ioread16(&mdev->common->queue_size);
+
+}
+
 /* virtio config->finalize_features() implementation */
 static int vp_finalize_features(struct virtio_device *vdev)
 {
@@ -487,7 +517,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
 	vp_iowrite16(index, &cfg->queue_select);
 
 	/* Check if queue is either not available or already active. */
-	num = vp_ioread16(&cfg->queue_size);
+	num = vp_modern_get_queue_size(mdev, index);
 	if (!num || vp_modern_get_queue_enable(mdev, index))
 		return ERR_PTR(-ENOENT);
 
@@ -510,7 +540,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
 		return ERR_PTR(-ENOMEM);
 
 	/* activate the queue */
-	vp_iowrite16(virtqueue_get_vring_size(vq), &cfg->queue_size);
+	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
 	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
 				virtqueue_get_avail_addr(vq),
 				virtqueue_get_used_addr(vq));