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From:   Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Subject: Re: [PATCH v3 09/16] iommu: Introduce guest PASID bind function
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>,
        iommu@lists.linux-foundation.org,
        LKML <linux-kernel@vger.kernel.org>,
        Joerg Roedel <joro@8bytes.org>,
        David Woodhouse <dwmw2@infradead.org>,
        Eric Auger <eric.auger@redhat.com>,
        Alex Williamson <alex.williamson@redhat.com>
Cc:     "Tian, Kevin" <kevin.tian@intel.com>,
        Raj Ashok <ashok.raj@intel.com>,
        Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
References: <1556922737-76313-1-git-send-email-jacob.jun.pan@linux.intel.com>
 <1556922737-76313-10-git-send-email-jacob.jun.pan@linux.intel.com>
Message-ID: <d652546a-c6ca-1cc6-1924-b016bd81a792@arm.com>
Date:   Thu, 16 May 2019 15:14:40 +0100
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Hi Jacob,

On 03/05/2019 23:32, Jacob Pan wrote:
> +/**
> + * struct gpasid_bind_data - Information about device and guest PASID binding
> + * @gcr3:	Guest CR3 value from guest mm
> + * @pasid:	Process address space ID used for the guest mm
> + * @addr_width:	Guest address width. Paging mode can also be derived.
> + */
> +struct gpasid_bind_data {
> +	__u64 gcr3;
> +	__u32 pasid;
> +	__u32 addr_width;
> +	__u32 flags;
> +#define	IOMMU_SVA_GPASID_SRE	BIT(0) /* supervisor request */
> +	__u8 padding[4];
> +};

Could you wrap this structure into a generic one like we now do for
bind_pasid_table? It would make the API easier to extend, because if we
ever add individual PASID bind on Arm (something I'd like to do for
virtio-iommu, eventually) it will have different parameters, as our
PASID table entry has a lot of fields describing the page table format.

Maybe something like the following would do?

struct gpasid_bind_data {
#define IOMMU_GPASID_BIND_VERSION_1 1
	__u32 version;
#define IOMMU_GPASID_BIND_FORMAT_INTEL_VTD	1
	__u32 format;
	union {
		// the current gpasid_bind_data:
		struct gpasid_bind_intel_vtd vtd;
	};
};

Thanks,
Jean