RE: [PATCH v1] vfio: ABI for mdev display dma-buf operation

[Zhang, Tina]

> -----Original Message-----
> From: Zhang, Tina
> Sent: Tuesday, July 4, 2017 9:04 AM
> To: alex.williamson@xxxxxxxxxx; kraxel@xxxxxxxxxx; chris@xxxxxxxxxxxxxxxxxx;
> zhenyuw@xxxxxxxxxxxxxxx; Lv, Zhiyuan <zhiyuan.lv@xxxxxxxxx>; Wang, Zhi A
> <zhi.a.wang@xxxxxxxxx>; Tian, Kevin <kevin.tian@xxxxxxxxx>; daniel@xxxxxxxx;
> kwankhede@xxxxxxxxxx
> Cc: Zhang, Tina <tina.zhang@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel-
> gvt-dev@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH v1] vfio: ABI for mdev display dma-buf operation
> 
> 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@xxxxxxxxx>
> 
> 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;
> +};
In this version, we don't rely on user mode to compare and find out whether a new dmabuf needs to be created. So, some of fields can be removed if user mode thinks they are not interesting any more. 

> +
> +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;
> +};
Still cannot figure out what the plane_id stands for in dmabuf case. As it might be needed by region usage, just add it here.

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