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Date:   Wed, 22 Sep 2021 15:24:07 -0600
From:   Alex Williamson <alex.williamson@redhat.com>
To:     Liu Yi L <yi.l.liu@intel.com>
Cc:     jgg@nvidia.com, hch@lst.de, jasowang@redhat.com, joro@8bytes.org,
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        kwankhede@nvidia.com, robin.murphy@arm.com, kvm@vger.kernel.org,
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        linux-kernel@vger.kernel.org, baolu.lu@linux.intel.com,
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Subject: Re: [RFC 10/20] iommu/iommufd: Add IOMMU_DEVICE_GET_INFO
Message-ID: <20210922152407.1bfa6ff7.alex.williamson@redhat.com>
In-Reply-To: <20210919063848.1476776-11-yi.l.liu@intel.com>
References: <20210919063848.1476776-1-yi.l.liu@intel.com>
        <20210919063848.1476776-11-yi.l.liu@intel.com>
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On Sun, 19 Sep 2021 14:38:38 +0800
Liu Yi L <yi.l.liu@intel.com> wrote:

> +struct iommu_device_info {
> +	__u32	argsz;
> +	__u32	flags;
> +#define IOMMU_DEVICE_INFO_ENFORCE_SNOOP	(1 << 0) /* IOMMU enforced snoop */

Is this too PCI specific, or perhaps too much of the mechanism rather
than the result?  ie. should we just indicate if the IOMMU guarantees
coherent DMA?  Thanks,

Alex

> +#define IOMMU_DEVICE_INFO_PGSIZES	(1 << 1) /* supported page sizes */
> +#define IOMMU_DEVICE_INFO_ADDR_WIDTH	(1 << 2) /* addr_wdith field valid */
> +	__u64	dev_cookie;
> +	__u64   pgsize_bitmap;
> +	__u32	addr_width;
> +};
> +
> +#define IOMMU_DEVICE_GET_INFO	_IO(IOMMU_TYPE, IOMMU_BASE + 1)
>  
>  #define IOMMU_FAULT_PERM_READ	(1 << 0) /* read */
>  #define IOMMU_FAULT_PERM_WRITE	(1 << 1) /* write */