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Date: Tue, 14 Apr 2026 11:34:14 -0600
From: Keith Busch <kbusch@kernel.org>
To: Leon Romanovsky <leon@kernel.org>
Cc: Zhiping Zhang <zhipingz@meta.com>, Jason Gunthorpe <jgg@ziepe.ca>,
	Bjorn Helgaas <bhelgaas@google.com>, linux-rdma@vger.kernel.org,
	linux-pci@vger.kernel.org, netdev@vger.kernel.org,
	dri-devel@lists.freedesktop.org, Yochai Cohen <yochai@nvidia.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	Bjorn Helgaas <helgaas@kernel.org>
Subject: Re: [RFC v2 1/2] vfio: add callback to get tph info for dmabuf
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In-Reply-To: <20260409120415.GF86584@unreal>

On Thu, Apr 09, 2026 at 03:04:15PM +0300, Leon Romanovsky wrote:
> Something like that, on top of this proposal:

...
  
> +struct vfio_region_dma_tph {
> +	u16 tag;
> +	u8 ph;
> +};
> +
>  struct vfio_region_dma_range {
> -	__u64 offset;
> -	__u64 length;
> +	union {
> +		__u64 offset;
> +		struct vfio_region_dma_tph tph;
> +	};
> +	union {
> +		__u64 length;
> +		__u64 reserved;
> +	};
> +};
> +
> +enum {
> +	VFIO_DMABUF_FLAG_TPH = 1 << 0,
>  };

Okay, so you have the hints as a separate action from the dmabuf
creation. I was trying to set it up in one shot, but this proposal may
be fine. We'll try this idea out internally.