Re: [PATCH v18 5/6] vfio: ABI for mdev display dma-buf operation

[Kirti Wankhede <kwankhede@nvidia.com>]

Extremely sorry for the delay.
This works for VFIO_GFX_PLANE_TYPE_REGION. Tested with local changes.

Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>

Thanks,
Kirti

On 11/18/2017 9:00 PM, Alex Williamson wrote:
> 
> Kirti?
> 
> On Wed, 15 Nov 2017 21:11:42 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
> 
>> On Thu, 16 Nov 2017 11:21:56 +0800
>> Zhenyu Wang <zhenyuw@linux.intel.com> wrote:
>>
>>> On 2017.11.15 11:48:42 -0700, Alex Williamson wrote:  
>>>> On Wed, 15 Nov 2017 17:11:54 +0800
>>>> Tina Zhang <tina.zhang@intel.com> wrote:
>>>>     
>>>>> Add VFIO_DEVICE_QUERY_GFX_PLANE ioctl command to let user query and get
>>>>> a plane and its information. So far, two types of buffers are supported:
>>>>> buffers based on dma-buf and buffers based on region.
>>>>>
>>>>> This ioctl can be invoked with:
>>>>> 1) Either DMABUF or REGION flag. Vendor driver returns a plane_info
>>>>> successfully only when the specific kind of buffer is supported.
>>>>> 2) Flag PROBE. And at the same time either DMABUF or REGION must be set,
>>>>> so that vendor driver returns success only when the specific kind of
>>>>> buffer is supported.
>>>>>
>>>>> Add VFIO_DEVICE_GET_GFX_DMABUF ioctl command to let user get a specific
>>>>> dma-buf fd of an exposed MDEV buffer provided by dmabuf_id which was
>>>>> returned in VFIO_DEVICE_QUERY_GFX_PLANE ioctl command.
>>>>>
>>>>> The life cycle of an exposed MDEV buffer is handled by userspace and
>>>>> tracked by kernel space. The returned dmabuf_id in struct vfio_device_
>>>>> query_gfx_plane can be a new id of a new exposed buffer or an old id of
>>>>> a re-exported buffer. Host user can check the value of dmabuf_id to see
>>>>> if it needs to create new resources according to the new exposed buffer
>>>>> or just re-use the existing resource related to the old buffer.
>>>>>
>>>>> v18:
>>>>> - update comments for VFIO_DEVICE_GET_GFX_DMABUF. (Alex)
>>>>>
>>>>> v17:
>>>>> - modify VFIO_DEVICE_GET_GFX_DMABUF interface. (Alex)
>>>>>
>>>>> v16:
>>>>> - add x_hot and y_hot fields. (Gerd)
>>>>> - add comments for VFIO_DEVICE_GET_GFX_DMABUF. (Alex)
>>>>> - rebase to 4.14.0-rc6.
>>>>>
>>>>> v15:
>>>>> - add a ioctl to get a dmabuf for a given dmabuf id. (Gerd)
>>>>>
>>>>> v14:
>>>>> - add PROBE, DMABUF and REGION flags. (Alex)
>>>>>
>>>>> v12:
>>>>> - add drm_format_mod back. (Gerd and Zhenyu)
>>>>> - add region_index. (Gerd)
>>>>>
>>>>> v11:
>>>>> - rename plane_type to drm_plane_type. (Gerd)
>>>>> - move fields of vfio_device_query_gfx_plane to vfio_device_gfx_plane_info.
>>>>>   (Gerd)
>>>>> - remove drm_format_mod, start fields. (Daniel)
>>>>> - remove plane_id.
>>>>>
>>>>> v10:
>>>>> - refine the ABI API VFIO_DEVICE_QUERY_GFX_PLANE. (Alex) (Gerd)
>>>>>
>>>>> v3:
>>>>> - add a field gvt_plane_info in the drm_i915_gem_obj structure to save
>>>>>   the decoded plane information to avoid look up while need the plane
>>>>>   info. (Gerd)
>>>>>
>>>>> Signed-off-by: Tina Zhang <tina.zhang@intel.com>
>>>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>>>> Cc: Alex Williamson <alex.williamson@redhat.com>
>>>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>> ---
>>>>>  include/uapi/linux/vfio.h | 62 +++++++++++++++++++++++++++++++++++++++++++++++
>>>>>  1 file changed, 62 insertions(+)
>>>>>
>>>>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>>>>> index ae46105..5c1cca2 100644
>>>>> --- a/include/uapi/linux/vfio.h
>>>>> +++ b/include/uapi/linux/vfio.h
>>>>> @@ -502,6 +502,68 @@ 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)
>>>>> + *
>>>>> + * Set the drm_plane_type and flags, then retrieve the gfx plane info.
>>>>> + *
>>>>> + * flags supported:
>>>>> + * - VFIO_GFX_PLANE_TYPE_PROBE and VFIO_GFX_PLANE_TYPE_DMABUF are set
>>>>> + *   to ask if the mdev supports dma-buf. 0 on support, -EINVAL on no
>>>>> + *   support for dma-buf.
>>>>> + * - VFIO_GFX_PLANE_TYPE_PROBE and VFIO_GFX_PLANE_TYPE_REGION are set
>>>>> + *   to ask if the mdev supports region. 0 on support, -EINVAL on no
>>>>> + *   support for region.
>>>>> + * - VFIO_GFX_PLANE_TYPE_DMABUF or VFIO_GFX_PLANE_TYPE_REGION is set
>>>>> + *   with each call to query the plane info.
>>>>> + * - Others are invalid and return -EINVAL.
>>>>> + *
>>>>> + * Note:
>>>>> + * 1. Plane could be disabled by guest. In that case, success will be
>>>>> + *    returned with zero-initialized drm_format, size, width and height
>>>>> + *    fields.
>>>>> + * 2. x_hot/y_hot is set to 0xFFFFFFFF if no hotspot information available
>>>>> + *
>>>>> + * Return: 0 on success, -errno on other failure.
>>>>> + */
>>>>> +struct vfio_device_gfx_plane_info {
>>>>> +	__u32 argsz;
>>>>> +	__u32 flags;
>>>>> +#define VFIO_GFX_PLANE_TYPE_PROBE (1 << 0)
>>>>> +#define VFIO_GFX_PLANE_TYPE_DMABUF (1 << 1)
>>>>> +#define VFIO_GFX_PLANE_TYPE_REGION (1 << 2)
>>>>> +	/* in */
>>>>> +	__u32 drm_plane_type;	/* type of plane: DRM_PLANE_TYPE_* */
>>>>> +	/* out */
>>>>> +	__u32 drm_format;	/* drm format of plane */
>>>>> +	__u64 drm_format_mod;   /* tiled mode */
>>>>> +	__u32 width;	/* width of plane */
>>>>> +	__u32 height;	/* height of plane */
>>>>> +	__u32 stride;	/* stride of plane */
>>>>> +	__u32 size;	/* size of plane in bytes, align on page*/
>>>>> +	__u32 x_pos;	/* horizontal position of cursor plane */
>>>>> +	__u32 y_pos;	/* vertical position of cursor plane*/
>>>>> +	__u32 x_hot;    /* horizontal position of cursor hotspot */
>>>>> +	__u32 y_hot;    /* vertical position of cursor hotspot */
>>>>> +	union {
>>>>> +		__u32 region_index;	/* region index */
>>>>> +		__u32 dmabuf_id;	/* dma-buf id */
>>>>> +	};
>>>>> +};
>>>>> +
>>>>> +#define VFIO_DEVICE_QUERY_GFX_PLANE _IO(VFIO_TYPE, VFIO_BASE + 14)
>>>>> +
>>>>> +/**
>>>>> + * VFIO_DEVICE_GET_GFX_DMABUF - _IOW(VFIO_TYPE, VFIO_BASE + 15, __u32)
>>>>> + *
>>>>> + * Return a new dma-buf file descriptor for an exposed guest framebuffer
>>>>> + * described by the provided dmabuf_id. The dmabuf_id is returned from VFIO_
>>>>> + * DEVICE_QUERY_GFX_PLANE as a token of the exposed guest framebuffer.
>>>>> + */
>>>>> +
>>>>> +#define VFIO_DEVICE_GET_GFX_DMABUF _IO(VFIO_TYPE, VFIO_BASE + 15)
>>>>> +
>>>>>  /* -------- API for Type1 VFIO IOMMU -------- */
>>>>>  
>>>>>  /**    
>>>>
>>>> Looks good to me.  Kirti, have you had a chance yet to verify this is
>>>> sufficient for your region-based approach?  It would be great to get
>>>> confirmation of that ASAP so we can get this in.  Thanks,
>>>>     
>>>
>>> Alex, do you mind by merging this just through gvt tree? Or you would
>>> like to merge this then send pull request for us then we can apply left?  
>>
>> I'm fine with this going through the gvt tree, but I want some
>> confirmation from nvidia that this meets their needs as well before I
>> provide an ack.  Thanks,
>>
>> Alex