> -----Original Message----- > From: Gerd Hoffmann [mailto:[email protected]] > Sent: Tuesday, June 20, 2017 6:58 PM > To: Zhang, Tina <[email protected]>; Alex Williamson > <[email protected]> > Cc: [email protected]; [email protected]; Kirti > Wankhede <[email protected]>; Chen, Xiaoguang > <[email protected]>; [email protected]; Lv, Zhiyuan > <[email protected]>; Wang, Zhi A <[email protected]>; Wang, Zhenyu > Z <[email protected]> > Subject: Re: [Intel-gfx] [PATCH v9 5/7] vfio: Define vfio based dma-buf > operations > > On Tue, 2017-06-20 at 08:41 +0000, Zhang, Tina wrote: > > Hi, > > > > Thanks for all the comments. Here are the summaries: > > > > 1. Modify the structures to make it more general. > > struct vfio_device_gfx_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 generation; > > }; > > Looks good to me. > > > struct vfio_device_query_gfx_plane { > > __u32 argsz; > > __u32 flags; > > #define VFIO_GFX_PLANE_FLAGS_REGION_ID (1 << 0) > > #define VFIO_GFX_PLANE_FLAGS_PLANE_ID (1 << 1) > > struct vfio_device_gfx_plane_info plane_info; > > __u32 id; > > }; > > I'm not convinced the flags are a great idea. Whenever dmabufs or a region is > used is a static property of the device, not of each individual plane. > > > I think we should have this for userspace to figure: > > enum vfio_device_gfx_type { > VFIO_DEVICE_GFX_NONE, > VFIO_DEVICE_GFX_DMABUF, > VFIO_DEVICE_GFX_REGION, > }; > > struct vfio_device_gfx_query_caps { > __u32 argsz; > __u32 flags; > enum vfio_device_gfx_type; > }; > > > Then this to query the plane: > > struct vfio_device_gfx_query_plane { > __u32 argsz; > __u32 flags; > struct vfio_device_gfx_plane_info plane_info; /* out */ > __u32 plane_type; /* in */ > }; > > > 2. Remove dmabuf mgr fd and add these two ioctl commands to the vfio device > fd. > > VFIO_DEVICE_QUERY_GFX_PLANE : used to query > > vfio_device_gfx_plane_info. > > Yes. > > > VFIO_DEVICE_GET_DMABUF_FD: used to create and return the dmabuf fd. > > Yes. The plane might have changed between query-plane and get-dmabuf ioctl > calls though, we must make sure we handle that somehow. Current patches > return plane_info on get-dmabuf ioctl too, so userspace can see what it > actually > got. > > With the generation we can also do something different: Pass in plane_type > and > generation, and have VFIO_DEVICE_GET_DMABUF_FD return an error in case > the generation doesn't match. In that case it doesn't make much sense any > more to have a separate plane_info struct, which was added so we don't have > to duplicate things in query-plane and get- dmabuf ioctl structs. Comparing with the current patch, this would make user space a little bit harder to get the dmabuf by calling VFIO_DEVICE_GET_DMABUF ioctl. Is it efficient for user mode usage?
Thanks Tina > > cheers, > Gerd
