vduse: add vq group support

This allows separate the different virtqueues in groups that shares the
same address space.  Asking the VDUSE device for the groups of the vq at
the beginning as they're needed for the DMA API.

Allocating 3 vq groups as net is the device that need the most groups:
* Dataplane (guest passthrough)
* CVQ
* Shadowed vrings.

Future versions of the series can include dynamic allocation of the
groups array so VDUSE can declare more groups.

Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Xie Yongji <xieyongji@bytedance.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20260119143306.1818855-4-eperezma@redhat.com>

Author: eugpermar

drivers/vdpa/vdpa_user/vduse_dev.c

@@ -39,6 +39,7 @@
 #define DRV_LICENSE  "GPL v2"
 
 #define VDUSE_DEV_MAX (1U << MINORBITS)
+#define VDUSE_DEV_MAX_GROUPS 0xffff
 #define VDUSE_MAX_BOUNCE_SIZE (1024 * 1024 * 1024)
 #define VDUSE_MIN_BOUNCE_SIZE (1024 * 1024)
 #define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
@@ -58,6 +59,7 @@ struct vduse_virtqueue {
 	struct vdpa_vq_state state;
 	bool ready;
 	bool kicked;
+	u32 group;
 	spinlock_t kick_lock;
 	spinlock_t irq_lock;
 	struct eventfd_ctx *kickfd;
@@ -114,6 +116,7 @@ struct vduse_dev {
 	u8 status;
 	u32 vq_num;
 	u32 vq_align;
+	u32 ngroups;
 	struct vduse_umem *umem;
 	struct mutex mem_lock;
 	unsigned int bounce_size;
@@ -592,6 +595,16 @@ static int vduse_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 idx,
 	return 0;
 }
 
+static u32 vduse_get_vq_group(struct vdpa_device *vdpa, u16 idx)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	if (dev->api_version < VDUSE_API_VERSION_1)
+		return 0;
+
+	return dev->vqs[idx]->group;
+}
+
 static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
 				struct vdpa_vq_state *state)
 {
@@ -789,6 +802,7 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
 	.set_vq_cb		= vduse_vdpa_set_vq_cb,
 	.set_vq_num             = vduse_vdpa_set_vq_num,
 	.get_vq_size		= vduse_vdpa_get_vq_size,
+	.get_vq_group		= vduse_get_vq_group,
 	.set_vq_ready		= vduse_vdpa_set_vq_ready,
 	.get_vq_ready		= vduse_vdpa_get_vq_ready,
 	.set_vq_state		= vduse_vdpa_set_vq_state,
@@ -1252,12 +1266,24 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
 		if (config.index >= dev->vq_num)
 			break;
 
-		if (!is_mem_zero((const char *)config.reserved,
-				 sizeof(config.reserved)))
+		if (dev->api_version < VDUSE_API_VERSION_1) {
+			if (config.group)
+				break;
+		} else {
+			if (config.group >= dev->ngroups)
+				break;
+			if (dev->status & VIRTIO_CONFIG_S_DRIVER_OK)
+				break;
+		}
+
+		if (config.reserved1 ||
+		    !is_mem_zero((const char *)config.reserved2,
+				 sizeof(config.reserved2)))
 			break;
 
 		index = array_index_nospec(config.index, dev->vq_num);
 		dev->vqs[index]->num_max = config.max_size;
+		dev->vqs[index]->group = config.group;
 		ret = 0;
 		break;
 	}
@@ -1737,12 +1763,20 @@ static bool features_is_valid(struct vduse_dev_config *config)
 	return true;
 }
 
-static bool vduse_validate_config(struct vduse_dev_config *config)
+static bool vduse_validate_config(struct vduse_dev_config *config,
+				  u64 api_version)
 {
 	if (!is_mem_zero((const char *)config->reserved,
 			 sizeof(config->reserved)))
 		return false;
 
+	if (api_version < VDUSE_API_VERSION_1 && config->ngroups)
+		return false;
+
+	if (api_version >= VDUSE_API_VERSION_1 &&
+	    (!config->ngroups || config->ngroups > VDUSE_DEV_MAX_GROUPS))
+		return false;
+
 	if (config->vq_align > PAGE_SIZE)
 		return false;
 
@@ -1858,6 +1892,9 @@ static int vduse_create_dev(struct vduse_dev_config *config,
 	dev->device_features = config->features;
 	dev->device_id = config->device_id;
 	dev->vendor_id = config->vendor_id;
+	dev->ngroups = (dev->api_version < VDUSE_API_VERSION_1)
+		       ? 1
+		       : config->ngroups;
 	dev->name = kstrdup(config->name, GFP_KERNEL);
 	if (!dev->name)
 		goto err_str;
@@ -1936,7 +1973,7 @@ static long vduse_ioctl(struct file *file, unsigned int cmd,
 			break;
 
 		ret = -EINVAL;
-		if (vduse_validate_config(&config) == false)
+		if (!vduse_validate_config(&config, control->api_version))
 			break;
 
 		buf = vmemdup_user(argp + size, config.config_size);
@@ -2017,7 +2054,7 @@ static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name)
 
 	vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, dev->dev,
 				 &vduse_vdpa_config_ops, &vduse_map_ops,
-				 1, 1, name, true);
+				 dev->ngroups, 1, name, true);
 	if (IS_ERR(vdev))
 		return PTR_ERR(vdev);
 

include/uapi/linux/vduse.h

@@ -31,6 +31,7 @@
  * @features: virtio features
  * @vq_num: the number of virtqueues
  * @vq_align: the allocation alignment of virtqueue's metadata
+ * @ngroups: number of vq groups that VDUSE device declares
  * @reserved: for future use, needs to be initialized to zero
  * @config_size: the size of the configuration space
  * @config: the buffer of the configuration space
@@ -45,7 +46,8 @@ struct vduse_dev_config {
 	__u64 features;
 	__u32 vq_num;
 	__u32 vq_align;
-	__u32 reserved[13];
+	__u32 ngroups; /* if VDUSE_API_VERSION >= 1 */
+	__u32 reserved[12];
 	__u32 config_size;
 	__u8 config[];
 };
@@ -122,14 +124,18 @@ struct vduse_config_data {
  * struct vduse_vq_config - basic configuration of a virtqueue
  * @index: virtqueue index
  * @max_size: the max size of virtqueue
- * @reserved: for future use, needs to be initialized to zero
+ * @reserved1: for future use, needs to be initialized to zero
+ * @group: virtqueue group
+ * @reserved2: for future use, needs to be initialized to zero
  *
  * Structure used by VDUSE_VQ_SETUP ioctl to setup a virtqueue.
  */
 struct vduse_vq_config {
 	__u32 index;
 	__u16 max_size;
-	__u16 reserved[13];
+	__u16 reserved1;
+	__u32 group;
+	__u16 reserved2[10];
 };
 
 /*