Hi Jason,

-----Original Message-----
From: Jason Wang [mailto:jasowang@redhat.com]
Sent: Tuesday, January 18, 2022 11:08 AM
To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
[off-list ref]; 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)
[off-list ref]; Yechuan [off-list ref]; Huangzhichao
[off-list ref]
Subject: Re: [RFC 2/3] vdpa: support exposing the count of vqs to userspace


在 2022/1/17 下午5:29, Longpeng(Mike) 写道:

quoted

From: Longpeng <redacted>

- GET_VQS_COUNT: the count of virtqueues that exposed

Signed-off-by: Longpeng <redacted>
---
  drivers/vhost/vdpa.c       | 13 +++++++++++++
  include/uapi/linux/vhost.h |  3 +++
  2 files changed, 16 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 1eea14a4ea56..c1074278fc6b 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -369,6 +369,16 @@ static long vhost_vdpa_get_config_size(struct vhost_vdpa

*v, u32 __user *argp)

quoted

  	return 0;
  }

+static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;

While at it, I think it's better to change vdpa->nvqs to use u32?

struct vhost_vdpa {
    ...
	int nvqs;
    ...
};

struct vdpa_device {
    ...
	int nvqs;
    ...
};

I think we should change both to u32?

Thanks

quoted

+
+	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 +519,9 @@ 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)

diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index bc74e95a273a..5d99e7c242a2 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