Re: [RFC 2/3] vdpa: support exposing the count of vqs to userspace

[Jason Wang <jasowang@redhat.com>]

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On Thu, Mar 10, 2022 at 11:16 AM Longpeng (Mike, Cloud Infrastructure
Service Product Dept.) <longpeng2@huawei.com> wrote:

> 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.)
> > <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>
> > 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:
> > > From: Longpeng <longpeng2@huawei.com>
> > >
> > > - GET_VQS_COUNT: the count of virtqueues that exposed
> > >
> > > Signed-off-by: Longpeng <longpeng2@huawei.com>
> > > ---
> > >   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)
> > >     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?
>

Yes.

Thanks


>
>
> > Thanks
> >
> >
> > > +
> > > +   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
>
>

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