> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: Tuesday, June 20, 2017 11:00 PM > To: Gerd Hoffmann <kraxel@xxxxxxxxxx> > Cc: Zhang, Tina <tina.zhang@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; Kirti Wankhede <kwankhede@xxxxxxxxxx>; Chen, > Xiaoguang <xiaoguang.chen@xxxxxxxxx>; intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx; > Lv, Zhiyuan <zhiyuan.lv@xxxxxxxxx>; Wang, Zhi A <zhi.a.wang@xxxxxxxxx>; > Wang, Zhenyu Z <zhenyu.z.wang@xxxxxxxxx> > Subject: Re: [PATCH v9 5/7] vfio: Define vfio based dma-buf > operations > > On Tue, 20 Jun 2017 12:57:36 +0200 > Gerd Hoffmann <kraxel@xxxxxxxxxx> wrote: > > > 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; > > }; > > We already have VFIO_DEVICE_GET_INFO which returns: > > struct vfio_device_info { > __u32 argsz; > __u32 flags; > #define VFIO_DEVICE_FLAGS_RESET (1 << 0) /* Device supports reset */ > #define VFIO_DEVICE_FLAGS_PCI (1 << 1) /* vfio-pci device */ > #define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2) /* vfio-platform device */ > #define VFIO_DEVICE_FLAGS_AMBA (1 << 3) /* vfio-amba device */ > #define VFIO_DEVICE_FLAGS_CCW (1 << 4) /* vfio-ccw device */ > __u32 num_regions; /* Max region index + 1 */ > __u32 num_irqs; /* Max IRQ index + 1 */ > }; > > We could use two flag bits to indicate dmabuf or graphics region support. > vfio_device_gfx_query_caps seems to imply a new ioctl, which would be > unnecessary. > > > 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 */ > > }; > > I'm not sure why we're using an enum for something that can currently be > defined with 2 bits, seems like this would be another good use of flags. We > could even embed an enum into the flags if we want to leave some expansion > room, 4 bits maybe? Also, I was imagining that a device could support multiple > graphics regions, that's where specifying the "id" as a region index seemed > useful. We lose that ability here unless we go back to defining a flag bit to > specify how to interpret this last field. > > > 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. > > I'm not convinced this adds value, but I'll list it as an option: > > VFIO_DEVICE_QUERY(VFIO_DEVICE_GFX_PLANE) > VFIO_DEVICE_GET_FD(VFIO_DEVICE_GFX_DMABUF_FD) > > The benefit is that it might help to avoid a proliferation of ioctls on the device the > pain is that we need to either define a field or section of flags which identify > what is being queried or what type of device fd is being requested. I didn't understand here. The patch introduces three ioctl commands: VFIO_DEVICE_GET_FD, VFIO_DMABUF_MGR_QUERY_PLANE, VFIO_DMABUF_MGR_CREATE_DMABUF. What I mean was we could remove the first one, a.k.a VFIO_DEVICE_GET_FD, which is used to get the fd of dmabuf mgr, as we want to remove the logic of dmabuf mgr. For the other two ioctls, I think we can give them new names which looks like more general. So, do you mean there is another way instead of ioctls? Thanks. BR, Tina > > 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. > > I'm not sure I understand how this works for a region, the region is always the > current generation, how can the user ever be sure the plane_info matches what > is exposed in the region? Thanks, > > Alex _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
