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Subject: Re: [PATCH 4/6] iommu: Combine device strictness requests with the
 global default
To:     Douglas Anderson <dianders@chromium.org>,
        gregkh@linuxfoundation.org, rafael@kernel.org,
        rafael.j.wysocki@intel.com, will@kernel.org, robin.murphy@arm.com,
        joro@8bytes.org, bjorn.andersson@linaro.org,
        ulf.hansson@linaro.org, adrian.hunter@intel.com,
        bhelgaas@google.com
References: <20210621235248.2521620-1-dianders@chromium.org>
 <20210621165230.4.Id84a954e705fcad3fdb35beb2bc372e4bf2108c7@changeid>
From:   Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <a86c2f9c-f66a-3a12-cf80-6e3fc6dafda4@linux.intel.com>
Date:   Tue, 22 Jun 2021 10:03:45 +0800
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On 6/22/21 7:52 AM, Douglas Anderson wrote:
> @@ -1519,7 +1542,8 @@ static int iommu_get_def_domain_type(struct device *dev)
>   
>   static int iommu_group_alloc_default_domain(struct bus_type *bus,
>   					    struct iommu_group *group,
> -					    unsigned int type)
> +					    unsigned int type,
> +					    struct device *dev)
>   {
>   	struct iommu_domain *dom;
>   
> @@ -1534,6 +1558,12 @@ static int iommu_group_alloc_default_domain(struct bus_type *bus,
>   	if (!dom)
>   		return -ENOMEM;
>   
> +	/* Save the strictness requests from the device */
> +	if (dev && type == IOMMU_DOMAIN_DMA) {
> +		dom->request_non_strict = dev->request_non_strict_iommu;
> +		dom->force_strict = dev->force_strict_iommu;
> +	}
> +

An iommu default domain might be used by multiple devices which might
have different "strict" attributions. Then who could override who?

Best regards,
baolu