virtio: introduce virtio_map container union

Following patch will introduce the mapping operations for virtio
device. In order to achieve this, besides the dma device, virtio core
needs to support a transport or device specific mapping metadata as well.
So this patch introduces a union container of a dma device. The idea
is the allow the transport layer to pass device specific mapping
metadata which will be used as a parameter for the virtio mapping
operations. For the transport or device that is using DMA, dma device
is still being used.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20250821064641.5025-5-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Eugenio Pérez <eperezma@redhat.com>

Author: jasowang

drivers/virtio/virtio_ring.c

@@ -210,8 +210,7 @@ struct vring_virtqueue {
 	/* DMA, allocation, and size information */
 	bool we_own_ring;
 
-	/* Device used for doing DMA */
-	struct device *dma_dev;
+	union virtio_map map;
 
 #ifdef DEBUG
 	/* They're supposed to lock for us. */
@@ -307,10 +306,10 @@ EXPORT_SYMBOL_GPL(virtio_max_dma_size);
 
 static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
 			       dma_addr_t *dma_handle, gfp_t flag,
-			       struct device *dma_dev)
+			       union virtio_map map)
 {
 	if (vring_use_map_api(vdev)) {
-		return dma_alloc_coherent(dma_dev, size,
+		return dma_alloc_coherent(map.dma_dev, size,
 					  dma_handle, flag);
 	} else {
 		void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
@@ -341,10 +340,10 @@ static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
 
 static void vring_free_queue(struct virtio_device *vdev, size_t size,
 			     void *queue, dma_addr_t dma_handle,
-			     struct device *dma_dev)
+			     union virtio_map map)
 {
 	if (vring_use_map_api(vdev))
-		dma_free_coherent(dma_dev, size, queue, dma_handle);
+		dma_free_coherent(map.dma_dev, size, queue, dma_handle);
 	else
 		free_pages_exact(queue, PAGE_ALIGN(size));
 }
@@ -356,7 +355,7 @@ static void vring_free_queue(struct virtio_device *vdev, size_t size,
  */
 static struct device *vring_dma_dev(const struct vring_virtqueue *vq)
 {
-	return vq->dma_dev;
+	return vq->map.dma_dev;
 }
 
 /* Map one sg entry. */
@@ -1056,12 +1055,13 @@ static int vring_alloc_state_extra_split(struct vring_virtqueue_split *vring_spl
 }
 
 static void vring_free_split(struct vring_virtqueue_split *vring_split,
-			     struct virtio_device *vdev, struct device *dma_dev)
+			     struct virtio_device *vdev,
+			     union virtio_map map)
 {
 	vring_free_queue(vdev, vring_split->queue_size_in_bytes,
 			 vring_split->vring.desc,
 			 vring_split->queue_dma_addr,
-			 dma_dev);
+			 map);
 
 	kfree(vring_split->desc_state);
 	kfree(vring_split->desc_extra);
@@ -1072,7 +1072,7 @@ static int vring_alloc_queue_split(struct vring_virtqueue_split *vring_split,
 				   u32 num,
 				   unsigned int vring_align,
 				   bool may_reduce_num,
-				   struct device *dma_dev)
+				   union virtio_map map)
 {
 	void *queue = NULL;
 	dma_addr_t dma_addr;
@@ -1088,7 +1088,7 @@ static int vring_alloc_queue_split(struct vring_virtqueue_split *vring_split,
 		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
 					  &dma_addr,
 					  GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
-					  dma_dev);
+					  map);
 		if (queue)
 			break;
 		if (!may_reduce_num)
@@ -1102,7 +1102,7 @@ static int vring_alloc_queue_split(struct vring_virtqueue_split *vring_split,
 		/* Try to get a single page. You are my only hope! */
 		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
 					  &dma_addr, GFP_KERNEL | __GFP_ZERO,
-					  dma_dev);
+					  map);
 	}
 	if (!queue)
 		return -ENOMEM;
@@ -1126,7 +1126,7 @@ static struct virtqueue *__vring_new_virtqueue_split(unsigned int index,
 					       bool (*notify)(struct virtqueue *),
 					       void (*callback)(struct virtqueue *),
 					       const char *name,
-					       struct device *dma_dev)
+					       union virtio_map map)
 {
 	struct vring_virtqueue *vq;
 	int err;
@@ -1149,7 +1149,7 @@ static struct virtqueue *__vring_new_virtqueue_split(unsigned int index,
 #else
 	vq->broken = false;
 #endif
-	vq->dma_dev = dma_dev;
+	vq->map = map;
 	vq->use_map_api = vring_use_map_api(vdev);
 
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
@@ -1187,21 +1187,21 @@ static struct virtqueue *vring_create_virtqueue_split(
 	bool (*notify)(struct virtqueue *),
 	void (*callback)(struct virtqueue *),
 	const char *name,
-	struct device *dma_dev)
+	union virtio_map map)
 {
 	struct vring_virtqueue_split vring_split = {};
 	struct virtqueue *vq;
 	int err;
 
 	err = vring_alloc_queue_split(&vring_split, vdev, num, vring_align,
-				      may_reduce_num, dma_dev);
+				      may_reduce_num, map);
 	if (err)
 		return NULL;
 
 	vq = __vring_new_virtqueue_split(index, &vring_split, vdev, weak_barriers,
-				   context, notify, callback, name, dma_dev);
+				   context, notify, callback, name, map);
 	if (!vq) {
-		vring_free_split(&vring_split, vdev, dma_dev);
+		vring_free_split(&vring_split, vdev, map);
 		return NULL;
 	}
 
@@ -1220,7 +1220,7 @@ static int virtqueue_resize_split(struct virtqueue *_vq, u32 num)
 	err = vring_alloc_queue_split(&vring_split, vdev, num,
 				      vq->split.vring_align,
 				      vq->split.may_reduce_num,
-				      vring_dma_dev(vq));
+				      vq->map);
 	if (err)
 		goto err;
 
@@ -1238,7 +1238,7 @@ static int virtqueue_resize_split(struct virtqueue *_vq, u32 num)
 	return 0;
 
 err_state_extra:
-	vring_free_split(&vring_split, vdev, vring_dma_dev(vq));
+	vring_free_split(&vring_split, vdev, vq->map);
 err:
 	virtqueue_reinit_split(vq);
 	return -ENOMEM;
@@ -1947,33 +1947,33 @@ static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num)
 
 static void vring_free_packed(struct vring_virtqueue_packed *vring_packed,
 			      struct virtio_device *vdev,
-			      struct device *dma_dev)
+			      union virtio_map map)
 {
 	if (vring_packed->vring.desc)
 		vring_free_queue(vdev, vring_packed->ring_size_in_bytes,
 				 vring_packed->vring.desc,
 				 vring_packed->ring_dma_addr,
-				 dma_dev);
+				 map);
 
 	if (vring_packed->vring.driver)
 		vring_free_queue(vdev, vring_packed->event_size_in_bytes,
 				 vring_packed->vring.driver,
 				 vring_packed->driver_event_dma_addr,
-				 dma_dev);
+				 map);
 
 	if (vring_packed->vring.device)
 		vring_free_queue(vdev, vring_packed->event_size_in_bytes,
 				 vring_packed->vring.device,
 				 vring_packed->device_event_dma_addr,
-				 dma_dev);
+				 map);
 
 	kfree(vring_packed->desc_state);
 	kfree(vring_packed->desc_extra);
 }
 
 static int vring_alloc_queue_packed(struct vring_virtqueue_packed *vring_packed,
 				    struct virtio_device *vdev,
-				    u32 num, struct device *dma_dev)
+				    u32 num, union virtio_map map)
 {
 	struct vring_packed_desc *ring;
 	struct vring_packed_desc_event *driver, *device;
@@ -1985,7 +1985,7 @@ static int vring_alloc_queue_packed(struct vring_virtqueue_packed *vring_packed,
 	ring = vring_alloc_queue(vdev, ring_size_in_bytes,
 				 &ring_dma_addr,
 				 GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
-				 dma_dev);
+				 map);
 	if (!ring)
 		goto err;
 
@@ -1998,7 +1998,7 @@ static int vring_alloc_queue_packed(struct vring_virtqueue_packed *vring_packed,
 	driver = vring_alloc_queue(vdev, event_size_in_bytes,
 				   &driver_event_dma_addr,
 				   GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
-				   dma_dev);
+				   map);
 	if (!driver)
 		goto err;
 
@@ -2009,7 +2009,7 @@ static int vring_alloc_queue_packed(struct vring_virtqueue_packed *vring_packed,
 	device = vring_alloc_queue(vdev, event_size_in_bytes,
 				   &device_event_dma_addr,
 				   GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
-				   dma_dev);
+				   map);
 	if (!device)
 		goto err;
 
@@ -2021,7 +2021,7 @@ static int vring_alloc_queue_packed(struct vring_virtqueue_packed *vring_packed,
 	return 0;
 
 err:
-	vring_free_packed(vring_packed, vdev, dma_dev);
+	vring_free_packed(vring_packed, vdev, map);
 	return -ENOMEM;
 }
 
@@ -2097,7 +2097,7 @@ static struct virtqueue *__vring_new_virtqueue_packed(unsigned int index,
 					       bool (*notify)(struct virtqueue *),
 					       void (*callback)(struct virtqueue *),
 					       const char *name,
-					       struct device *dma_dev)
+					       union virtio_map map)
 {
 	struct vring_virtqueue *vq;
 	int err;
@@ -2120,7 +2120,7 @@ static struct virtqueue *__vring_new_virtqueue_packed(unsigned int index,
 	vq->broken = false;
 #endif
 	vq->packed_ring = true;
-	vq->dma_dev = dma_dev;
+	vq->map = map;
 	vq->use_map_api = vring_use_map_api(vdev);
 
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
@@ -2158,18 +2158,18 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	bool (*notify)(struct virtqueue *),
 	void (*callback)(struct virtqueue *),
 	const char *name,
-	struct device *dma_dev)
+	union virtio_map map)
 {
 	struct vring_virtqueue_packed vring_packed = {};
 	struct virtqueue *vq;
 
-	if (vring_alloc_queue_packed(&vring_packed, vdev, num, dma_dev))
+	if (vring_alloc_queue_packed(&vring_packed, vdev, num, map))
 		return NULL;
 
 	vq = __vring_new_virtqueue_packed(index, &vring_packed, vdev, weak_barriers,
-					context, notify, callback, name, dma_dev);
+					context, notify, callback, name, map);
 	if (!vq) {
-		vring_free_packed(&vring_packed, vdev, dma_dev);
+		vring_free_packed(&vring_packed, vdev, map);
 		return NULL;
 	}
 
@@ -2185,7 +2185,7 @@ static int virtqueue_resize_packed(struct virtqueue *_vq, u32 num)
 	struct virtio_device *vdev = _vq->vdev;
 	int err;
 
-	if (vring_alloc_queue_packed(&vring_packed, vdev, num, vring_dma_dev(vq)))
+	if (vring_alloc_queue_packed(&vring_packed, vdev, num, vq->map))
 		goto err_ring;
 
 	err = vring_alloc_state_extra_packed(&vring_packed);
@@ -2202,7 +2202,7 @@ static int virtqueue_resize_packed(struct virtqueue *_vq, u32 num)
 	return 0;
 
 err_state_extra:
-	vring_free_packed(&vring_packed, vdev, vring_dma_dev(vq));
+	vring_free_packed(&vring_packed, vdev, vq->map);
 err_ring:
 	virtqueue_reinit_packed(vq);
 	return -ENOMEM;
@@ -2434,7 +2434,7 @@ struct device *virtqueue_dma_dev(struct virtqueue *_vq)
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
 	if (vq->use_map_api)
-		return vring_dma_dev(vq);
+		return vq->map.dma_dev;
 	else
 		return NULL;
 }
@@ -2719,19 +2719,20 @@ struct virtqueue *vring_create_virtqueue(
 	void (*callback)(struct virtqueue *),
 	const char *name)
 {
+	union virtio_map map = {.dma_dev = vdev->dev.parent};
 
 	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
 		return vring_create_virtqueue_packed(index, num, vring_align,
 				vdev, weak_barriers, may_reduce_num,
-				context, notify, callback, name, vdev->dev.parent);
+				context, notify, callback, name, map);
 
 	return vring_create_virtqueue_split(index, num, vring_align,
 			vdev, weak_barriers, may_reduce_num,
-			context, notify, callback, name, vdev->dev.parent);
+			context, notify, callback, name, map);
 }
 EXPORT_SYMBOL_GPL(vring_create_virtqueue);
 
-struct virtqueue *vring_create_virtqueue_dma(
+struct virtqueue *vring_create_virtqueue_map(
 	unsigned int index,
 	unsigned int num,
 	unsigned int vring_align,
@@ -2742,19 +2743,19 @@ struct virtqueue *vring_create_virtqueue_dma(
 	bool (*notify)(struct virtqueue *),
 	void (*callback)(struct virtqueue *),
 	const char *name,
-	struct device *dma_dev)
+	union virtio_map map)
 {
 
 	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
 		return vring_create_virtqueue_packed(index, num, vring_align,
 				vdev, weak_barriers, may_reduce_num,
-				context, notify, callback, name, dma_dev);
+				context, notify, callback, name, map);
 
 	return vring_create_virtqueue_split(index, num, vring_align,
 			vdev, weak_barriers, may_reduce_num,
-			context, notify, callback, name, dma_dev);
+			context, notify, callback, name, map);
 }
-EXPORT_SYMBOL_GPL(vring_create_virtqueue_dma);
+EXPORT_SYMBOL_GPL(vring_create_virtqueue_map);
 
 /**
  * virtqueue_resize - resize the vring of vq
@@ -2865,6 +2866,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
 				      const char *name)
 {
 	struct vring_virtqueue_split vring_split = {};
+	union virtio_map map = {.dma_dev = vdev->dev.parent};
 
 	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
 		struct vring_virtqueue_packed vring_packed = {};
@@ -2874,13 +2876,13 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
 		return __vring_new_virtqueue_packed(index, &vring_packed,
 						    vdev, weak_barriers,
 						    context, notify, callback,
-						    name, vdev->dev.parent);
+						    name, map);
 	}
 
 	vring_init(&vring_split.vring, num, pages, vring_align);
 	return __vring_new_virtqueue_split(index, &vring_split, vdev, weak_barriers,
 				     context, notify, callback, name,
-				     vdev->dev.parent);
+				     map);
 }
 EXPORT_SYMBOL_GPL(vring_new_virtqueue);
 
@@ -2894,19 +2896,19 @@ static void vring_free(struct virtqueue *_vq)
 					 vq->packed.ring_size_in_bytes,
 					 vq->packed.vring.desc,
 					 vq->packed.ring_dma_addr,
-					 vring_dma_dev(vq));
+					 vq->map);
 
 			vring_free_queue(vq->vq.vdev,
 					 vq->packed.event_size_in_bytes,
 					 vq->packed.vring.driver,
 					 vq->packed.driver_event_dma_addr,
-					 vring_dma_dev(vq));
+					 vq->map);
 
 			vring_free_queue(vq->vq.vdev,
 					 vq->packed.event_size_in_bytes,
 					 vq->packed.vring.device,
 					 vq->packed.device_event_dma_addr,
-					 vring_dma_dev(vq));
+					 vq->map);
 
 			kfree(vq->packed.desc_state);
 			kfree(vq->packed.desc_extra);
@@ -2915,7 +2917,7 @@ static void vring_free(struct virtqueue *_vq)
 					 vq->split.queue_size_in_bytes,
 					 vq->split.vring.desc,
 					 vq->split.queue_dma_addr,
-					 vring_dma_dev(vq));
+					 vq->map);
 		}
 	}
 	if (!vq->packed_ring) {