[PATCH v2 04/23] virtio: Add get_shm_region method

[Vivek Goyal]

Hi Gurchetan,

Now Miklos has queued, these tree virtio patches for shared memory
region in his tree as part of virtiofs dax patch series.

I am hoping this will get merged in 5.10 through his tree.

https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git/log/?h=dax

Thanks
Vivek

On Wed, Sep 02, 2020 at 02:08:28PM -0700, Gurchetan Singh wrote:
> From: Sebastien Boeuf <sebastien.boeuf at intel.com>
> 
> Virtio defines 'shared memory regions' that provide a continuously
> shared region between the host and guest.
> 
> Provide a method to find a particular region on a device.
> 
> Signed-off-by: Sebastien Boeuf <sebastien.boeuf at intel.com>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert at redhat.com>
> Acked-by: Michael S. Tsirkin <mst at redhat.com>
> Cc: kvm at vger.kernel.org
> Cc: virtualization at lists.linux-foundation.org
> Cc: "Michael S. Tsirkin" <mst at redhat.com>
> ---
>  include/linux/virtio_config.h | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 8fe857e27ef32..4b8e38c5c4d8c 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -11,6 +11,11 @@
>  
>  struct irq_affinity;
>  
> +struct virtio_shm_region {
> +	u64 addr;
> +	u64 len;
> +};
> +
>  /**
>   * virtio_config_ops - operations for configuring a virtio device
>   * Note: Do not assume that a transport implements all of the operations
> @@ -66,6 +71,7 @@ struct irq_affinity;
>   *      the caller can then copy.
>   * @set_vq_affinity: set the affinity for a virtqueue (optional).
>   * @get_vq_affinity: get the affinity for a virtqueue (optional).
> + * @get_shm_region: get a shared memory region based on the index.
>   */
>  typedef void vq_callback_t(struct virtqueue *);
>  struct virtio_config_ops {
> @@ -89,6 +95,8 @@ struct virtio_config_ops {
>  			       const struct cpumask *cpu_mask);
>  	const struct cpumask *(*get_vq_affinity)(struct virtio_device *vdev,
>  			int index);
> +	bool (*get_shm_region)(struct virtio_device *vdev,
> +			       struct virtio_shm_region *region, u8 id);
>  };
>  
>  /* If driver didn't advertise the feature, it will never appear. */
> @@ -251,6 +259,15 @@ int virtqueue_set_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask)
>  	return 0;
>  }
>  
> +static inline
> +bool virtio_get_shm_region(struct virtio_device *vdev,
> +			   struct virtio_shm_region *region, u8 id)
> +{
> +	if (!vdev->config->get_shm_region)
> +		return false;
> +	return vdev->config->get_shm_region(vdev, region, id);
> +}
> +
>  static inline bool virtio_is_little_endian(struct virtio_device *vdev)
>  {
>  	return virtio_has_feature(vdev, VIRTIO_F_VERSION_1) ||
> -- 
> 2.26.2
>