From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [PATCH v9 5/7] vfio: Define vfio based dma-buf operations
Date: Mon, 19 Jun 2017 08:38:32 +0200
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Cc: Xiaoguang Chen <xiaoguang.chen@intel.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
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  Hi,

> My suggestion was to use vfio device fd for this ioctl and have
> dmabuf
> mgr fd as member in above query_plane structure, for region type it
> would be set to 0.

Region type should be DRM_PLANE_TYPE_PRIMARY

> Can't mmap that page to get surface information. There is no way to
> synchronize between QEMU reading this mmapped region and vendor
> driver
> writing it. There could be race condition in these two operations.
> Read
> on this page should be trapped and blocking, so that surface in that
> region is only updated when its asked for.

Does it make sense to have a "generation" field in the plane_info
struct (which gets increased each time the struct changes) ?

cheers,
  Gerd