Re: [PATCH v9 5/7] vfio: Define vfio based dma-buf operations

From: Gerd Hoffmann <kraxel@redhat.com>
To: Kirti Wankhede <kwankhede@nvidia.com>,
	Xiaoguang Chen <xiaoguang.chen@intel.com>,
	alex.williamson@redhat.com, chris@chris-wilson.co.uk,
	intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	zhenyuw@linux.intel.com, zhiyuan.lv@intel.com,
	intel-gvt-dev@lists.freedesktop.org, zhi.a.wang@intel.com,
	kevin.tian@intel.com
Subject: Re: [PATCH v9 5/7] vfio: Define vfio based dma-buf operations
Date: Thu, 15 Jun 2017 18:00:38 +0200	[thread overview]
Message-ID: <1497542438.29252.1.camel@redhat.com> (raw)
In-Reply-To: <f19da207-a7f5-d3d3-4577-b071e7d75cf7@nvidia.com>

  Hi,

> > +struct vfio_dmabuf_mgr_plane_info {
> > +	__u64 start;
> > +	__u64 drm_format_mod;
> > +	__u32 drm_format;
> > +	__u32 width;
> > +	__u32 height;
> > +	__u32 stride;
> > +	__u32 size;
> > +	__u32 x_pos;
> > +	__u32 y_pos;
> > +	__u32 padding;
> > +};
> > +
> 
> This structure is generic, can remove dmabuf from its name,
> vfio_plane_info or vfio_vgpu_surface_info since this will only be
> used
> by vgpu.

Agree.

> > +struct vfio_dmabuf_mgr_query_plane {
> > +	__u32 argsz;
> > +	__u32 flags;
> > +	struct vfio_dmabuf_mgr_plane_info plane_info;
> > +	__u32 plane_id;
> > +};
> > +
> > +#define VFIO_DMABUF_MGR_QUERY_PLANE _IO(VFIO_TYPE, VFIO_BASE + 15)
> > +
> 
> This same interface can be used to query surface/plane information
> for
> both, dmabuf and region, case. Here also 'DMABUF' can be removed and
> define flags if you want to differentiate query for 'dmabuf' and
> 'region'.

Hmm, any specific reason why you want use a ioctl for that?  I would
simply place a "struct vfio_dmabuf_mgr_plane_info" (or whatever the
final name will be) at the start of the region.

cheers,
  Gerd

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