[PATCH v2 0/2] vdpa: add two ioctl commands to support generic vDPA

[PATCH v2 0/2] vdpa: add two ioctl commands to support generic vDPA

[Longpeng(Mike)]

From: Longpeng <longpeng2@huawei.com>

To support generic vdpa deivce[1], we need add the following ioctls:
  - GET_CONFIG_SIZE: the size of the virtio config space (Patch 1)
  - GET_VQS_COUNT: the count of virtqueues that exposed (Patch 2)

Changes v1(RFC) -> v2:
  Patch 1:
    - be more verbose in commit message and the comment for get_config_size
      [Jason]
  Patch 2:
    - change the type of nvqs to u32 [Jason]
  Patch 3:
    - drop from this series because Gautam sent another proposal[2]

[1] https://lore.kernel.org/all/20220105005900.860-1-longpeng2@huawei.com/
[2] https://patchwork.kernel.org/project/kvm/patch/20220224212314.1326-20-gdawar@xilinx.com/

Longpeng (2):
  vdpa: support exposing the config size to userspace
  vdpa: support exposing the count of vqs to userspace

 drivers/vdpa/vdpa.c        |  6 +++---
 drivers/vhost/vdpa.c       | 40 ++++++++++++++++++++++++++++++++++++----
 include/linux/vdpa.h       |  9 +++++----
 include/uapi/linux/vhost.h |  7 +++++++
 4 files changed, 51 insertions(+), 11 deletions(-)

-- 
1.8.3.1

[PATCH v2 1/2] vdpa: support exposing the config size to userspace

[Longpeng(Mike)]

From: Longpeng <longpeng2@huawei.com>

- GET_CONFIG_SIZE: return the size of the virtio config space.

The size contains the fields which are conditional on feature
bits.

Signed-off-by: Longpeng <longpeng2@huawei.com>
---
 drivers/vhost/vdpa.c       | 17 +++++++++++++++++
 include/linux/vdpa.h       |  3 ++-
 include/uapi/linux/vhost.h |  4 ++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index ec5249e..605c7ae 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -355,6 +355,20 @@ static long vhost_vdpa_get_iova_range(struct vhost_vdpa *v, u32 __user *argp)
 	return 0;
 }
 
+static long vhost_vdpa_get_config_size(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 size;
+
+	size = ops->get_config_size(vdpa);
+
+	if (copy_to_user(argp, &size, sizeof(size)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 				   void __user *argp)
 {
@@ -492,6 +506,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 	case VHOST_VDPA_GET_IOVA_RANGE:
 		r = vhost_vdpa_get_iova_range(v, argp);
 		break;
+	case VHOST_VDPA_GET_CONFIG_SIZE:
+		r = vhost_vdpa_get_config_size(v, argp);
+		break;
 	default:
 		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
 		if (r == -ENOIOCTLCMD)
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 721089b..a526919 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -207,7 +207,8 @@ struct vdpa_map_file {
  * @reset:			Reset device
  *				@vdev: vdpa device
  *				Returns integer: success (0) or error (< 0)
- * @get_config_size:		Get the size of the configuration space
+ * @get_config_size:		Get the size of the configuration space includes
+ *				fields that are conditional on feature bits.
  *				@vdev: vdpa device
  *				Returns size_t: configuration size
  * @get_config:			Read from device specific configuration space
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index c998860..bc74e95 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -150,4 +150,8 @@
 /* Get the valid iova range */
 #define VHOST_VDPA_GET_IOVA_RANGE	_IOR(VHOST_VIRTIO, 0x78, \
 					     struct vhost_vdpa_iova_range)
+
+/* Get the config size */
+#define VHOST_VDPA_GET_CONFIG_SIZE	_IOR(VHOST_VIRTIO, 0x79, __u32)
+
 #endif
-- 
1.8.3.1

Re: [PATCH v2 1/2] vdpa: support exposing the config size to userspace

[Jason Wang]

在 2022/3/10 下午3:20, Longpeng(Mike) 写道:
> From: Longpeng <longpeng2@huawei.com>
>
> - GET_CONFIG_SIZE: return the size of the virtio config space.
>
> The size contains the fields which are conditional on feature
> bits.
>
> Signed-off-by: Longpeng <longpeng2@huawei.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   drivers/vhost/vdpa.c       | 17 +++++++++++++++++
>   include/linux/vdpa.h       |  3 ++-
>   include/uapi/linux/vhost.h |  4 ++++
>   3 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index ec5249e..605c7ae 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -355,6 +355,20 @@ static long vhost_vdpa_get_iova_range(struct vhost_vdpa *v, u32 __user *argp)
>   	return 0;
>   }
>   
> +static long vhost_vdpa_get_config_size(struct vhost_vdpa *v, u32 __user *argp)
> +{
> +	struct vdpa_device *vdpa = v->vdpa;
> +	const struct vdpa_config_ops *ops = vdpa->config;
> +	u32 size;
> +
> +	size = ops->get_config_size(vdpa);
> +
> +	if (copy_to_user(argp, &size, sizeof(size)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
>   static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
>   				   void __user *argp)
>   {
> @@ -492,6 +506,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
>   	case VHOST_VDPA_GET_IOVA_RANGE:
>   		r = vhost_vdpa_get_iova_range(v, argp);
>   		break;
> +	case VHOST_VDPA_GET_CONFIG_SIZE:
> +		r = vhost_vdpa_get_config_size(v, argp);
> +		break;
>   	default:
>   		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
>   		if (r == -ENOIOCTLCMD)
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 721089b..a526919 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -207,7 +207,8 @@ struct vdpa_map_file {
>    * @reset:			Reset device
>    *				@vdev: vdpa device
>    *				Returns integer: success (0) or error (< 0)
> - * @get_config_size:		Get the size of the configuration space
> + * @get_config_size:		Get the size of the configuration space includes
> + *				fields that are conditional on feature bits.
>    *				@vdev: vdpa device
>    *				Returns size_t: configuration size
>    * @get_config:			Read from device specific configuration space
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index c998860..bc74e95 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -150,4 +150,8 @@
>   /* Get the valid iova range */
>   #define VHOST_VDPA_GET_IOVA_RANGE	_IOR(VHOST_VIRTIO, 0x78, \
>   					     struct vhost_vdpa_iova_range)
> +
> +/* Get the config size */
> +#define VHOST_VDPA_GET_CONFIG_SIZE	_IOR(VHOST_VIRTIO, 0x79, __u32)
> +
>   #endif

[PATCH v2 2/2] vdpa: support exposing the count of vqs to userspace

[Longpeng(Mike)]

From: Longpeng <longpeng2@huawei.com>

- GET_VQS_COUNT: the count of virtqueues that exposed

And change vdpa_device.nvqs and vhost_vdpa.nvqs to use u32.

Signed-off-by: Longpeng <longpeng2@huawei.com>
---
 drivers/vdpa/vdpa.c        |  6 +++---
 drivers/vhost/vdpa.c       | 23 +++++++++++++++++++----
 include/linux/vdpa.h       |  6 +++---
 include/uapi/linux/vhost.h |  3 +++
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 1ea5254..2b75c00 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -232,7 +232,7 @@ static int vdpa_name_match(struct device *dev, const void *data)
 	return (strcmp(dev_name(&vdev->dev), data) == 0);
 }
 
-static int __vdpa_register_device(struct vdpa_device *vdev, int nvqs)
+static int __vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
 {
 	struct device *dev;
 
@@ -257,7 +257,7 @@ static int __vdpa_register_device(struct vdpa_device *vdev, int nvqs)
  *
  * Return: Returns an error when fail to add device to vDPA bus
  */
-int _vdpa_register_device(struct vdpa_device *vdev, int nvqs)
+int _vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
 {
 	if (!vdev->mdev)
 		return -EINVAL;
@@ -274,7 +274,7 @@ int _vdpa_register_device(struct vdpa_device *vdev, int nvqs)
  *
  * Return: Returns an error when fail to add to vDPA bus
  */
-int vdpa_register_device(struct vdpa_device *vdev, int nvqs)
+int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
 {
 	int err;
 
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 605c7ae..69b3f05 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -42,7 +42,7 @@ struct vhost_vdpa {
 	struct device dev;
 	struct cdev cdev;
 	atomic_t opened;
-	int nvqs;
+	u32 nvqs;
 	int virtio_id;
 	int minor;
 	struct eventfd_ctx *config_ctx;
@@ -158,7 +158,8 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
 	struct vdpa_device *vdpa = v->vdpa;
 	const struct vdpa_config_ops *ops = vdpa->config;
 	u8 status, status_old;
-	int ret, nvqs = v->nvqs;
+	u32 nvqs = v->nvqs;
+	int ret;
 	u16 i;
 
 	if (copy_from_user(&status, statusp, sizeof(status)))
@@ -369,6 +370,16 @@ static long vhost_vdpa_get_config_size(struct vhost_vdpa *v, u32 __user *argp)
 	return 0;
 }
 
+static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+
+	if (copy_to_user(argp, &vdpa->nvqs, sizeof(vdpa->nvqs)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 				   void __user *argp)
 {
@@ -509,6 +520,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 	case VHOST_VDPA_GET_CONFIG_SIZE:
 		r = vhost_vdpa_get_config_size(v, argp);
 		break;
+	case VHOST_VDPA_GET_VQS_COUNT:
+		r = vhost_vdpa_get_vqs_count(v, argp);
+		break;
 	default:
 		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
 		if (r == -ENOIOCTLCMD)
@@ -965,7 +979,8 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
 	struct vhost_vdpa *v;
 	struct vhost_dev *dev;
 	struct vhost_virtqueue **vqs;
-	int nvqs, i, r, opened;
+	int r, opened;
+	u32 i, nvqs;
 
 	v = container_of(inode->i_cdev, struct vhost_vdpa, cdev);
 
@@ -1018,7 +1033,7 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
 
 static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
 {
-	int i;
+	u32 i;
 
 	for (i = 0; i < v->nvqs; i++)
 		vhost_vdpa_unsetup_vq_irq(v, i);
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index a526919..8943a20 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -83,7 +83,7 @@ struct vdpa_device {
 	unsigned int index;
 	bool features_valid;
 	bool use_va;
-	int nvqs;
+	u32 nvqs;
 	struct vdpa_mgmt_dev *mdev;
 };
 
@@ -338,10 +338,10 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
 				       dev_struct, member)), name, use_va), \
 				       dev_struct, member)
 
-int vdpa_register_device(struct vdpa_device *vdev, int nvqs);
+int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs);
 void vdpa_unregister_device(struct vdpa_device *vdev);
 
-int _vdpa_register_device(struct vdpa_device *vdev, int nvqs);
+int _vdpa_register_device(struct vdpa_device *vdev, u32 nvqs);
 void _vdpa_unregister_device(struct vdpa_device *vdev);
 
 /**
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index bc74e95..5d99e7c 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -154,4 +154,7 @@
 /* Get the config size */
 #define VHOST_VDPA_GET_CONFIG_SIZE	_IOR(VHOST_VIRTIO, 0x79, __u32)
 
+/* Get the count of all virtqueues */
+#define VHOST_VDPA_GET_VQS_COUNT	_IOR(VHOST_VIRTIO, 0x80, __u32)
+
 #endif
-- 
1.8.3.1

Re: [PATCH v2 2/2] vdpa: support exposing the count of vqs to userspace

[Jason Wang]

在 2022/3/10 下午3:20, Longpeng(Mike) 写道:
> From: Longpeng <longpeng2@huawei.com>
>
> - GET_VQS_COUNT: the count of virtqueues that exposed
>
> And change vdpa_device.nvqs and vhost_vdpa.nvqs to use u32.


Patch looks good, a nit is that we'd better use a separate patch for the 
u32 converting.

Thanks


>
> Signed-off-by: Longpeng <longpeng2@huawei.com>
> ---
>   drivers/vdpa/vdpa.c        |  6 +++---
>   drivers/vhost/vdpa.c       | 23 +++++++++++++++++++----
>   include/linux/vdpa.h       |  6 +++---
>   include/uapi/linux/vhost.h |  3 +++
>   4 files changed, 28 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 1ea5254..2b75c00 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -232,7 +232,7 @@ static int vdpa_name_match(struct device *dev, const void *data)
>   	return (strcmp(dev_name(&vdev->dev), data) == 0);
>   }
>   
> -static int __vdpa_register_device(struct vdpa_device *vdev, int nvqs)
> +static int __vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
>   {
>   	struct device *dev;
>   
> @@ -257,7 +257,7 @@ static int __vdpa_register_device(struct vdpa_device *vdev, int nvqs)
>    *
>    * Return: Returns an error when fail to add device to vDPA bus
>    */
> -int _vdpa_register_device(struct vdpa_device *vdev, int nvqs)
> +int _vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
>   {
>   	if (!vdev->mdev)
>   		return -EINVAL;
> @@ -274,7 +274,7 @@ int _vdpa_register_device(struct vdpa_device *vdev, int nvqs)
>    *
>    * Return: Returns an error when fail to add to vDPA bus
>    */
> -int vdpa_register_device(struct vdpa_device *vdev, int nvqs)
> +int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
>   {
>   	int err;
>   
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 605c7ae..69b3f05 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -42,7 +42,7 @@ struct vhost_vdpa {
>   	struct device dev;
>   	struct cdev cdev;
>   	atomic_t opened;
> -	int nvqs;
> +	u32 nvqs;
>   	int virtio_id;
>   	int minor;
>   	struct eventfd_ctx *config_ctx;
> @@ -158,7 +158,8 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
>   	struct vdpa_device *vdpa = v->vdpa;
>   	const struct vdpa_config_ops *ops = vdpa->config;
>   	u8 status, status_old;
> -	int ret, nvqs = v->nvqs;
> +	u32 nvqs = v->nvqs;
> +	int ret;
>   	u16 i;
>   
>   	if (copy_from_user(&status, statusp, sizeof(status)))
> @@ -369,6 +370,16 @@ static long vhost_vdpa_get_config_size(struct vhost_vdpa *v, u32 __user *argp)
>   	return 0;
>   }
>   
> +static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
> +{
> +	struct vdpa_device *vdpa = v->vdpa;
> +
> +	if (copy_to_user(argp, &vdpa->nvqs, sizeof(vdpa->nvqs)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
>   static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
>   				   void __user *argp)
>   {
> @@ -509,6 +520,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
>   	case VHOST_VDPA_GET_CONFIG_SIZE:
>   		r = vhost_vdpa_get_config_size(v, argp);
>   		break;
> +	case VHOST_VDPA_GET_VQS_COUNT:
> +		r = vhost_vdpa_get_vqs_count(v, argp);
> +		break;
>   	default:
>   		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
>   		if (r == -ENOIOCTLCMD)
> @@ -965,7 +979,8 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>   	struct vhost_vdpa *v;
>   	struct vhost_dev *dev;
>   	struct vhost_virtqueue **vqs;
> -	int nvqs, i, r, opened;
> +	int r, opened;
> +	u32 i, nvqs;
>   
>   	v = container_of(inode->i_cdev, struct vhost_vdpa, cdev);
>   
> @@ -1018,7 +1033,7 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>   
>   static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
>   {
> -	int i;
> +	u32 i;
>   
>   	for (i = 0; i < v->nvqs; i++)
>   		vhost_vdpa_unsetup_vq_irq(v, i);
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index a526919..8943a20 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -83,7 +83,7 @@ struct vdpa_device {
>   	unsigned int index;
>   	bool features_valid;
>   	bool use_va;
> -	int nvqs;
> +	u32 nvqs;
>   	struct vdpa_mgmt_dev *mdev;
>   };
>   
> @@ -338,10 +338,10 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
>   				       dev_struct, member)), name, use_va), \
>   				       dev_struct, member)
>   
> -int vdpa_register_device(struct vdpa_device *vdev, int nvqs);
> +int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs);
>   void vdpa_unregister_device(struct vdpa_device *vdev);
>   
> -int _vdpa_register_device(struct vdpa_device *vdev, int nvqs);
> +int _vdpa_register_device(struct vdpa_device *vdev, u32 nvqs);
>   void _vdpa_unregister_device(struct vdpa_device *vdev);
>   
>   /**
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index bc74e95..5d99e7c 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -154,4 +154,7 @@
>   /* Get the config size */
>   #define VHOST_VDPA_GET_CONFIG_SIZE	_IOR(VHOST_VIRTIO, 0x79, __u32)
>   
> +/* Get the count of all virtqueues */
> +#define VHOST_VDPA_GET_VQS_COUNT	_IOR(VHOST_VIRTIO, 0x80, __u32)
> +
>   #endif

RE: [PATCH v2 2/2] vdpa: support exposing the count of vqs to userspace

[Longpeng (Mike, Cloud Infrastructure Service Product Dept.)]

> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Monday, March 14, 2022 2:04 PM
> To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
> <longpeng2@huawei.com>; mst@redhat.com; sgarzare@redhat.com;
> stefanha@redhat.com
> Cc: virtualization@lists.linux-foundation.org; kvm@vger.kernel.org;
> linux-kernel@vger.kernel.org; netdev@vger.kernel.org; Gonglei (Arei)
> <arei.gonglei@huawei.com>; Yechuan <yechuan@huawei.com>; Huangzhichao
> <huangzhichao@huawei.com>; gdawar@xilinx.com
> Subject: Re: [PATCH v2 2/2] vdpa: support exposing the count of vqs to userspace
> 
> 
> 在 2022/3/10 下午3:20, Longpeng(Mike) 写道:
> > From: Longpeng <longpeng2@huawei.com>
> >
> > - GET_VQS_COUNT: the count of virtqueues that exposed
> >
> > And change vdpa_device.nvqs and vhost_vdpa.nvqs to use u32.
> 
> 
> Patch looks good, a nit is that we'd better use a separate patch for the
> u32 converting.
> 

OK, will do in v3, thanks.

> Thanks
> 
> 
> >
> > Signed-off-by: Longpeng <longpeng2@huawei.com>
> > ---
> >   drivers/vdpa/vdpa.c        |  6 +++---
> >   drivers/vhost/vdpa.c       | 23 +++++++++++++++++++----
> >   include/linux/vdpa.h       |  6 +++---
> >   include/uapi/linux/vhost.h |  3 +++
> >   4 files changed, 28 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > index 1ea5254..2b75c00 100644
> > --- a/drivers/vdpa/vdpa.c
> > +++ b/drivers/vdpa/vdpa.c
> > @@ -232,7 +232,7 @@ static int vdpa_name_match(struct device *dev, const void
> *data)
> >   	return (strcmp(dev_name(&vdev->dev), data) == 0);
> >   }
> >
> > -static int __vdpa_register_device(struct vdpa_device *vdev, int nvqs)
> > +static int __vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
> >   {
> >   	struct device *dev;
> >
> > @@ -257,7 +257,7 @@ static int __vdpa_register_device(struct vdpa_device *vdev,
> int nvqs)
> >    *
> >    * Return: Returns an error when fail to add device to vDPA bus
> >    */
> > -int _vdpa_register_device(struct vdpa_device *vdev, int nvqs)
> > +int _vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
> >   {
> >   	if (!vdev->mdev)
> >   		return -EINVAL;
> > @@ -274,7 +274,7 @@ int _vdpa_register_device(struct vdpa_device *vdev, int
> nvqs)
> >    *
> >    * Return: Returns an error when fail to add to vDPA bus
> >    */
> > -int vdpa_register_device(struct vdpa_device *vdev, int nvqs)
> > +int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs)
> >   {
> >   	int err;
> >
> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index 605c7ae..69b3f05 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -42,7 +42,7 @@ struct vhost_vdpa {
> >   	struct device dev;
> >   	struct cdev cdev;
> >   	atomic_t opened;
> > -	int nvqs;
> > +	u32 nvqs;
> >   	int virtio_id;
> >   	int minor;
> >   	struct eventfd_ctx *config_ctx;
> > @@ -158,7 +158,8 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v,
> u8 __user *statusp)
> >   	struct vdpa_device *vdpa = v->vdpa;
> >   	const struct vdpa_config_ops *ops = vdpa->config;
> >   	u8 status, status_old;
> > -	int ret, nvqs = v->nvqs;
> > +	u32 nvqs = v->nvqs;
> > +	int ret;
> >   	u16 i;
> >
> >   	if (copy_from_user(&status, statusp, sizeof(status)))
> > @@ -369,6 +370,16 @@ static long vhost_vdpa_get_config_size(struct vhost_vdpa
> *v, u32 __user *argp)
> >   	return 0;
> >   }
> >
> > +static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
> > +{
> > +	struct vdpa_device *vdpa = v->vdpa;
> > +
> > +	if (copy_to_user(argp, &vdpa->nvqs, sizeof(vdpa->nvqs)))
> > +		return -EFAULT;
> > +
> > +	return 0;
> > +}
> > +
> >   static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
> >   				   void __user *argp)
> >   {
> > @@ -509,6 +520,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
> >   	case VHOST_VDPA_GET_CONFIG_SIZE:
> >   		r = vhost_vdpa_get_config_size(v, argp);
> >   		break;
> > +	case VHOST_VDPA_GET_VQS_COUNT:
> > +		r = vhost_vdpa_get_vqs_count(v, argp);
> > +		break;
> >   	default:
> >   		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
> >   		if (r == -ENOIOCTLCMD)
> > @@ -965,7 +979,8 @@ static int vhost_vdpa_open(struct inode *inode, struct
> file *filep)
> >   	struct vhost_vdpa *v;
> >   	struct vhost_dev *dev;
> >   	struct vhost_virtqueue **vqs;
> > -	int nvqs, i, r, opened;
> > +	int r, opened;
> > +	u32 i, nvqs;
> >
> >   	v = container_of(inode->i_cdev, struct vhost_vdpa, cdev);
> >
> > @@ -1018,7 +1033,7 @@ static int vhost_vdpa_open(struct inode *inode, struct
> file *filep)
> >
> >   static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
> >   {
> > -	int i;
> > +	u32 i;
> >
> >   	for (i = 0; i < v->nvqs; i++)
> >   		vhost_vdpa_unsetup_vq_irq(v, i);
> > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> > index a526919..8943a20 100644
> > --- a/include/linux/vdpa.h
> > +++ b/include/linux/vdpa.h
> > @@ -83,7 +83,7 @@ struct vdpa_device {
> >   	unsigned int index;
> >   	bool features_valid;
> >   	bool use_va;
> > -	int nvqs;
> > +	u32 nvqs;
> >   	struct vdpa_mgmt_dev *mdev;
> >   };
> >
> > @@ -338,10 +338,10 @@ struct vdpa_device *__vdpa_alloc_device(struct device
> *parent,
> >   				       dev_struct, member)), name, use_va), \
> >   				       dev_struct, member)
> >
> > -int vdpa_register_device(struct vdpa_device *vdev, int nvqs);
> > +int vdpa_register_device(struct vdpa_device *vdev, u32 nvqs);
> >   void vdpa_unregister_device(struct vdpa_device *vdev);
> >
> > -int _vdpa_register_device(struct vdpa_device *vdev, int nvqs);
> > +int _vdpa_register_device(struct vdpa_device *vdev, u32 nvqs);
> >   void _vdpa_unregister_device(struct vdpa_device *vdev);
> >
> >   /**
> > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> > index bc74e95..5d99e7c 100644
> > --- a/include/uapi/linux/vhost.h
> > +++ b/include/uapi/linux/vhost.h
> > @@ -154,4 +154,7 @@
> >   /* Get the config size */
> >   #define VHOST_VDPA_GET_CONFIG_SIZE	_IOR(VHOST_VIRTIO, 0x79, __u32)
> >
> > +/* Get the count of all virtqueues */
> > +#define VHOST_VDPA_GET_VQS_COUNT	_IOR(VHOST_VIRTIO, 0x80, __u32)
> > +
> >   #endif