linux-kernel - Re: [PATCH 18/23] iommu: Express DMA strictness via the domain type

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Message-ID: <9b5abd19-8bfe-7215-8b13-108aea2aee5e@arm.com>
Date:   Mon, 26 Jul 2021 13:43:24 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>, joro@...tes.org,
        will@...nel.org
Cc:     linux-kernel@...r.kernel.org, dianders@...omium.org,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 18/23] iommu: Express DMA strictness via the domain type

On 2021-07-26 13:29, Lu Baolu wrote:
[...]
>>>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>>>> index b1af1ff324c5..a114a7ad88ec 100644
>>>> --- a/drivers/iommu/dma-iommu.c
>>>> +++ b/drivers/iommu/dma-iommu.c
>>>> @@ -363,13 +363,15 @@ static int iommu_dma_init_domain(struct 
>>>> iommu_domain *domain, dma_addr_t base,
>>>>       init_iova_domain(iovad, 1UL << order, base_pfn);
>>>> -    if (!cookie->fq_domain && !dev_is_untrusted(dev) &&
>>>> -        domain->ops->flush_iotlb_all && 
>>>> !iommu_get_dma_strict(domain)) {
>>>> +    if (domain->type == IOMMU_DOMAIN_DMA_FQ && !cookie->fq_domain &&
>>>> +        domain->ops->flush_iotlb_all) {
> 
> Perhaps we can remove the ops->flush_iotlb_all check with the
> assumption that any vendor iommu driver with DMA_FQ domain support
> should always provides this callback?

Oh yes, indeed it wouldn't make sense for a driver to claim 
IOMMU_DOMAIN_DMA_FQ support but not implement the one thing that that 
needs the driver to provide. That's yet another neat little cleanup, thanks!

Robin.