netdev - Re: [PATCH 16/18] iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH

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Message-ID: <163376d7-ab23-a470-5bba-7fcd8ae95a4e@arm.com>
Date:   Wed, 31 Mar 2021 17:07:56 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Christoph Hellwig <hch@....de>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>, Li Yang <leoyang.li@....com>
Cc:     freedreno@...ts.freedesktop.org, kvm@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, dri-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org,
        iommu@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        David Woodhouse <dwmw2@...radead.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 16/18] iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE

On 2021-03-16 15:38, Christoph Hellwig wrote:
[...]
> 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 f1e38526d5bd40..996dfdf9d375dd 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2017,7 +2017,7 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain,
>   		.iommu_dev	= smmu->dev,
>   	};
>   
> -	if (smmu_domain->non_strict)
> +	if (!iommu_get_dma_strict())

As Will raised, this also needs to be checking "domain->type == 
IOMMU_DOMAIN_DMA" to maintain equivalent behaviour to the attribute code 
below.

>   		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
>   
>   	pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
> @@ -2449,52 +2449,6 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
>   	return group;
>   }
>   
> -static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
> -				    enum iommu_attr attr, void *data)
> -{
> -	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> -
> -	switch (domain->type) {
> -	case IOMMU_DOMAIN_DMA:
> -		switch (attr) {
> -		case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
> -			*(int *)data = smmu_domain->non_strict;
> -			return 0;
> -		default:
> -			return -ENODEV;
> -		}
> -		break;
> -	default:
> -		return -EINVAL;
> -	}
> -}
[...]
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> index f985817c967a25..edb1de479dd1a7 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> @@ -668,7 +668,6 @@ struct arm_smmu_domain {
>   	struct mutex			init_mutex; /* Protects smmu pointer */
>   
>   	struct io_pgtable_ops		*pgtbl_ops;
> -	bool				non_strict;
>   	atomic_t			nr_ats_masters;
>   
>   	enum arm_smmu_domain_stage	stage;
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index 0aa6d667274970..3dde22b1f8ffb0 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -761,6 +761,9 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
>   		.iommu_dev	= smmu->dev,
>   	};
>   
> +	if (!iommu_get_dma_strict())

Ditto here.

Sorry for not spotting that sooner :(

Robin.

> +		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
> +
>   	if (smmu->impl && smmu->impl->init_context) {
>   		ret = smmu->impl->init_context(smmu_domain, &pgtbl_cfg, dev);
>   		if (ret)