Re: [PATCH v3 8/8] iommu/arm-smmu-v3: Make default domain type of HiSilicon PTT device to identity

From: John Garry via iommu <iommu@lists.linux-foundation.org>
To: Yicong Yang <yangyicong@hisilicon.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"helgaas@kernel.org" <helgaas@kernel.org>,
	"alexander.shishkin@linux.intel.com"
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	"will@kernel.org" <will@kernel.org>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
	"suzuki.poulose@arm.com" <suzuki.poulose@arm.com>,
	"mike.leach@linaro.org" <mike.leach@linaro.org>,
	"leo.yan@linaro.org" <leo.yan@linaro.org>,
	"Jonathan Cameron" <jonathan.cameron@huawei.com>,
	"daniel.thompson@linaro.org" <daniel.thompson@linaro.org>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"Shameerali Kolothum Thodi"
	<shameerali.kolothum.thodi@huawei.com>,
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Cc: Linuxarm <linuxarm@huawei.com>,
	Zhangshaokun <zhangshaokun@hisilicon.com>,
	"Zengtao \(B\)" <prime.zeng@hisilicon.com>,
	yangyicong <yangyicong@huawei.com>,
	"liuqi \(BA\)" <liuqi115@huawei.com>
Subject: Re: [PATCH v3 8/8] iommu/arm-smmu-v3: Make default domain type of HiSilicon PTT device to identity
Date: Tue, 8 Feb 2022 08:05:29 +0000	[thread overview]
Message-ID: <4f6f6e0f-4398-3018-cc35-6aa7ea1305fe@huawei.com> (raw)
In-Reply-To: <20220124131118.17887-9-yangyicong@hisilicon.com>

On 24/01/2022 13:11, Yicong Yang wrote:
> The DMA of HiSilicon PTT device can only work with identical
> mapping. So add a quirk for the device to force the domain
> passthrough.

This patch should be earlier in the series, before the PTT driver, and 
the comment on hisi_ptt_check_iommu_mapping() should mention what is 
going on here.

> 
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> ---
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 6dc6d8b6b368..6f67a2b1dd27 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2838,6 +2838,21 @@ static int arm_smmu_dev_disable_feature(struct device *dev,
>   	}
>   }
>   
> +#define IS_HISI_PTT_DEVICE(pdev)	((pdev)->vendor == PCI_VENDOR_ID_HUAWEI && \
> +					 (pdev)->device == 0xa12e)

I assume that not all revisions will require this check, right?

> +
> +static int arm_smmu_def_domain_type(struct device *dev)
> +{
> +	if (dev_is_pci(dev)) {
> +		struct pci_dev *pdev = to_pci_dev(dev);
> +
> +		if (IS_HISI_PTT_DEVICE(pdev))
> +			return IOMMU_DOMAIN_IDENTITY;
> +	}
> +
> +	return 0;
> +}
> +
>   static struct iommu_ops arm_smmu_ops = {
>   	.capable		= arm_smmu_capable,
>   	.domain_alloc		= arm_smmu_domain_alloc,
> @@ -2863,6 +2878,7 @@ static struct iommu_ops arm_smmu_ops = {
>   	.sva_unbind		= arm_smmu_sva_unbind,
>   	.sva_get_pasid		= arm_smmu_sva_get_pasid,
>   	.page_response		= arm_smmu_page_response,
> +	.def_domain_type	= arm_smmu_def_domain_type,
>   	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
>   	.owner			= THIS_MODULE,
>   };

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