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SubjectRe: [PATCH v10] vfio: ABI for mdev display dma-buf operation
On Thu, Jul 06, 2017 at 06:29:55AM +0800, Tina Zhang wrote:
> Add VFIO_DEVICE_QUERY_GFX_PLANE ioctl command to let user mode query and
> get the plan and its related information.
>
> The dma-buf's life cycle is handled by user mode and tracked by kernel.
> The returned fd in struct vfio_device_query_gfx_plane can be a new
> fd or an old fd of a re-exported dma-buf. Host User mode can check the
> value of fd and to see if it need to creat new resource according to the
> new fd or just use the existed resource related to the old fd.
>
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>
>
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index ae46105..c92bc69 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -502,6 +502,36 @@ struct vfio_pci_hot_reset {
>
> #define VFIO_DEVICE_PCI_HOT_RESET _IO(VFIO_TYPE, VFIO_BASE + 13)
>
> +/**
> + * VFIO_DEVICE_QUERY_GFX_PLANE - _IOW(VFIO_TYPE, VFIO_BASE + 14,
> + * struct vfio_device_query_gfx_plane)
> + * Return: 0 on success, -errno on failure.
> + */
> +
> +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;
> +};

Would be good to have a detailed spec of all this stuff, plus what's it
meant to be used for. I assume that e.g. start would be the opaque cookie
thing we've talked about, for dma-buf reuse? Otherwise I'm not sure what
it's good for, since the same gpu vram address can be reused for different
memory objects ...

> +
> +struct vfio_device_query_gfx_plane {
> + __u32 argsz;
> + __u32 flags;
> + struct vfio_device_gfx_plane_info plane_info;
> + __u32 plane_type;
> + __s32 fd; /* dma-buf fd */
> + __u32 plane_id;
> +};

As mentioned in the other reply already, I'm not sure what plane_type is
for. Otherwise this looks ok-ish, but hard to tell without more detailed
spec.
-Daniel

> +
> +#define VFIO_DEVICE_QUERY_GFX_PLANE _IO(VFIO_TYPE, VFIO_BASE + 14)
> +
> +
> /* -------- API for Type1 VFIO IOMMU -------- */
>
> /**
> --
> 2.7.4
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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