Re: [PATCH v2 2/8] vhost-vdpa: use bind_mm/unbind_mm device callbacks

Jason Wang
2023-03-14T03:49:38Z

On Thu, Mar 2, 2023 at 7:34 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> When the user call VHOST_SET_OWNER ioctl and the vDPA device
> has `use_va` set to true, let's call the bind_mm callback.
> In this way we can bind the device to the user address space
> and directly use the user VA.
>
> The unbind_mm callback is called during the release after
> stopping the device.
>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>
> Notes:
> v2:
> - call the new unbind_mm callback during the release [Jason]
> - avoid to call bind_mm callback after the reset, since the device
> is not detaching it now during the reset
>
> drivers/vhost/vdpa.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index dc12dbd5b43b..1ab89fccd825 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -219,6 +219,28 @@ static int vhost_vdpa_reset(struct vhost_vdpa *v)
> return vdpa_reset(vdpa);
> }
>
> +static long vhost_vdpa_bind_mm(struct vhost_vdpa *v)
> +{
> + struct vdpa_device *vdpa = v->vdpa;
> + const struct vdpa_config_ops *ops = vdpa->config;
> +
> + if (!vdpa->use_va || !ops->bind_mm)
> + return 0;
> +
> + return ops->bind_mm(vdpa, v->vdev.mm);
> +}
> +
> +static void vhost_vdpa_unbind_mm(struct vhost_vdpa *v)
> +{
> + struct vdpa_device *vdpa = v->vdpa;
> + const struct vdpa_config_ops *ops = vdpa->config;
> +
> + if (!vdpa->use_va || !ops->unbind_mm)
> + return;
> +
> + ops->unbind_mm(vdpa);
> +}
> +
> static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
> {
> struct vdpa_device *vdpa = v->vdpa;
> @@ -711,6 +733,13 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
> break;
> default:
> r = vhost_dev_ioctl(&v->vdev, cmd, argp);
> + if (!r && cmd == VHOST_SET_OWNER) {
> + r = vhost_vdpa_bind_mm(v);
> + if (r) {
> + vhost_dev_reset_owner(&v->vdev, NULL);
> + break;
> + }
> + }

Nit: is it better to have a new condition/switch branch instead of
putting them under default? (as what vring_ioctl did).

Thanks

> if (r == -ENOIOCTLCMD)
> r = vhost_vdpa_vring_ioctl(v, cmd, argp);
> break;
> @@ -1285,6 +1314,7 @@ static int vhost_vdpa_release(struct inode *inode, struct file *filep)
> vhost_vdpa_clean_irq(v);
> vhost_vdpa_reset(v);
> vhost_dev_stop(&v->vdev);
> + vhost_vdpa_unbind_mm(v);
> vhost_vdpa_free_domain(v);
> vhost_vdpa_config_put(v);
> vhost_vdpa_cleanup(v);
> --
> 2.39.2
>