On Wed, Sep 8, 2021 at 8:23 PM Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx> wrote:
>
> This new callback is used to indicate whether the vring size can be
> change or not. It is useful when we have a legacy virtio pci device as
> the vdpa device for there is no way to negotiate the vring num by the
> specification.
So I'm not sure it's worth bothering. E.g what if we just fail
VHOST_SET_VRING_NUM it the value doesn't match what hardware has?
Thanks
>
> Signed-off-by: Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx>
> ---
> drivers/vhost/vdpa.c | 19 +++++++++++++++++++
> drivers/virtio/virtio_vdpa.c | 5 ++++-
> include/linux/vdpa.h | 4 ++++
> include/uapi/linux/vhost.h | 2 ++
> 4 files changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 9479f7f79217..2204d27d1e5d 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -350,6 +350,22 @@ static long vhost_vdpa_get_iova_range(struct vhost_vdpa *v, u32 __user *argp)
> return 0;
> }
>
> +static long vhost_vdpa_get_vring_num_unchangeable(struct vhost_vdpa *v,
> + u32 __user *argp)
> +{
> + struct vdpa_device *vdpa = v->vdpa;
> + const struct vdpa_config_ops *ops = vdpa->config;
> + bool unchangeable = false;
> +
> + if (ops->get_vq_num_unchangeable)
> + unchangeable = ops->get_vq_num_unchangeable(vdpa);
> +
> + if (copy_to_user(argp, &unchangeable, sizeof(unchangeable)))
> + return -EFAULT;
> +
> + return 0;
> +}
> +
> static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
> void __user *argp)
> {
> @@ -487,6 +503,9 @@ 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_VRING_NUM_UNCHANGEABLE:
> + r = vhost_vdpa_get_vring_num_unchangeable(v, argp);
> + break;
> default:
> r = vhost_dev_ioctl(&v->vdev, cmd, argp);
> if (r == -ENOIOCTLCMD)
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index 72eaef2caeb1..afb47465307a 100644
> --- a/drivers/virtio/virtio_vdpa.c
> +++ b/drivers/virtio/virtio_vdpa.c
> @@ -146,6 +146,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
> struct vdpa_vq_state state = {0};
> unsigned long flags;
> u32 align, num;
> + bool may_reduce_num = true;
> int err;
>
> if (!name)
> @@ -171,8 +172,10 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>
> /* Create the vring */
> align = ops->get_vq_align(vdpa);
> + if (ops->get_vq_num_unchangeable)
> + may_reduce_num = !ops->get_vq_num_unchangeable(vdpa);
> vq = vring_create_virtqueue(index, num, align, vdev,
> - true, true, ctx,
> + true, may_reduce_num, ctx,
> virtio_vdpa_notify, callback, name);
> if (!vq) {
> err = -ENOMEM;
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 35648c11e312..f809b7ada00d 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -195,6 +195,9 @@ struct vdpa_iova_range {
> * @vdev: vdpa device
> * Returns the iova range supported by
> * the device.
> + * @get_vq_num_unchangeable Check if size of virtqueue is unchangeable (optional)
> + * @vdev: vdpa device
> + * Returns boolean: unchangeable (true) or not (false)
> * @set_map: Set device memory mapping (optional)
> * Needed for device that using device
> * specific DMA translation (on-chip IOMMU)
> @@ -262,6 +265,7 @@ struct vdpa_config_ops {
> const void *buf, unsigned int len);
> u32 (*get_generation)(struct vdpa_device *vdev);
> struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
> + bool (*get_vq_num_unchangeable)(struct vdpa_device *vdev);
>
> /* DMA ops */
> int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb);
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index c998860d7bbc..184f1f7f8498 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -150,4 +150,6 @@
> /* Get the valid iova range */
> #define VHOST_VDPA_GET_IOVA_RANGE _IOR(VHOST_VIRTIO, 0x78, \
> struct vhost_vdpa_iova_range)
> +/* Check if the vring size can be change */
> +#define VHOST_VDPA_GET_VRING_NUM_UNCHANGEABLE _IOR(VHOST_VIRTIO, 0X79, bool)
> #endif
> --
> 2.31.1
>
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