linux-kernel - Re: [PATCH 17/23] iommu/vt-d: Prepare for multiple DMA domain types

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Date:   Sat, 24 Jul 2021 13:23:33 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Robin Murphy <robin.murphy@....com>, joro@...tes.org,
        will@...nel.org
Cc:     baolu.lu@...ux.intel.com, iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        suravee.suthikulpanit@....com, john.garry@...wei.com,
        dianders@...omium.org
Subject: Re: [PATCH 17/23] iommu/vt-d: Prepare for multiple DMA domain types

Hi Robin,

On 2021/7/22 2:20, Robin Murphy wrote:
> In preparation for the strict vs. non-strict decision for DMA domains to
> be expressed in the domain type, make sure we expose our flush queue
> awareness by accepting the new domain type, and test the specific
> feature flag where we want to identify DMA domains in general. The DMA
> ops setup can simply be made unconditional, since iommu-dma already
> knows not to touch identity domains.
> 
> Signed-off-by: Robin Murphy <robin.murphy@....com>
> ---
>   drivers/iommu/intel/iommu.c | 15 ++++++---------
>   1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index e2add5a0caef..77d322272743 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -601,7 +601,7 @@ struct intel_iommu *domain_get_iommu(struct dmar_domain *domain)
>   	int iommu_id;
>   
>   	/* si_domain and vm domain should not get here. */
> -	if (WARN_ON(domain->domain.type != IOMMU_DOMAIN_DMA))
> +	if (WARN_ON(!(domain->domain.type & __IOMMU_DOMAIN_DMA)))
>   		return NULL;
>   
>   	for_each_domain_iommu(iommu_id, domain)
> @@ -1035,7 +1035,7 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
>   			pteval = ((uint64_t)virt_to_dma_pfn(tmp_page) << VTD_PAGE_SHIFT) | DMA_PTE_READ | DMA_PTE_WRITE;
>   			if (domain_use_first_level(domain)) {
>   				pteval |= DMA_FL_PTE_XD | DMA_FL_PTE_US;
> -				if (domain->domain.type == IOMMU_DOMAIN_DMA)
> +				if (domain->domain.type & __IOMMU_DOMAIN_DMA_API)
>   					pteval |= DMA_FL_PTE_ACCESS;
>   			}
>   			if (cmpxchg64(&pte->val, 0ULL, pteval))
> @@ -2346,7 +2346,7 @@ __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
>   	if (domain_use_first_level(domain)) {
>   		attr |= DMA_FL_PTE_XD | DMA_FL_PTE_US;
>   
> -		if (domain->domain.type == IOMMU_DOMAIN_DMA) {
> +		if (domain->domain.type & __IOMMU_DOMAIN_DMA_API) {
>   			attr |= DMA_FL_PTE_ACCESS;
>   			if (prot & DMA_PTE_WRITE)
>   				attr |= DMA_FL_PTE_DIRTY;
> @@ -4528,6 +4528,7 @@ static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
>   
>   	switch (type) {
>   	case IOMMU_DOMAIN_DMA:
> +	case IOMMU_DOMAIN_DMA_FQ:
>   	case IOMMU_DOMAIN_UNMANAGED:
>   		dmar_domain = alloc_domain(0);
>   		if (!dmar_domain) {
> @@ -5164,12 +5165,8 @@ static void intel_iommu_release_device(struct device *dev)
>   
>   static void intel_iommu_probe_finalize(struct device *dev)
>   {
> -	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> -
> -	if (domain && domain->type == IOMMU_DOMAIN_DMA)
> -		iommu_setup_dma_ops(dev, 0, U64_MAX);
> -	else
> -		set_dma_ops(dev, NULL);
> +	set_dma_ops(dev, NULL);

Is it reasonable to remove above line? The idea is that vendor iommu
driver should not override the dma_ops if device doesn't have a DMA
domain.

> +	iommu_setup_dma_ops(dev, 0, U64_MAX);
>   }
>   
>   static void intel_iommu_get_resv_regions(struct device *device,
> 

Best regards,
baolu