linux-kernel - Re: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain

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Date: Fri, 22 Dec 2023 11:59:38 +0000
From: "Liu, Yi L" <yi.l.liu@...el.com>
To: "Tian, Kevin" <kevin.tian@...el.com>
CC: "Yang, Weijiang" <weijiang.yang@...el.com>, "joro@...tes.org"
	<joro@...tes.org>, "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
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 Zhenzhong" <zhenzhong.duan@...el.com>, "joao.m.martins@...cle.com"
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Subject: Re: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain


> On Dec 22, 2023, at 15:12, Tian, Kevin <kevin.tian@...el.com> wrote:
> 
> 
>> 
>> From: Liu, Yi L <yi.l.liu@...el.com>
>> Sent: Friday, December 22, 2023 3:02 PM
>> 
>> 
>>>> On Dec 22, 2023, at 14:47, Tian, Kevin <kevin.tian@...el.com> wrote:
>>> 
>>> 
>>>> 
>>>> From: Yang, Weijiang <weijiang.yang@...el.com>
>>>> Sent: Friday, December 22, 2023 11:56 AM
>>>>> +
>>>>> +    xa_for_each(&domain->iommu_array, i, info) {
>>>>> +        nested_flush_pasid_iotlb(info->iommu, domain, addr,
>>>> npages, 0);
>>>>> +
>>>>> +        if (domain->has_iotlb_device)
>>>>> +            continue;
>>>> 
>>>> Shouldn't this be if (!domain->has_iotlb_device)?
>>> 
>>> yes that is wrong.
>>> 
>>> actually it's weird to put domain check in a loop of domain->iommu_array.
>>> 
>>> that check along with devtlb flush should be done out of that loop.
>> 
>> Maybe adding a bool, set it out of the loop, check the bool in the loop.
> 
> the point is that dev iotlb doesn't rely on info->iommu:
> 
>    nested_flush_dev_iotlb(domain, addr, mask, &fault);
> 
> then why do it in the loop of info->iommu?

yes. It should have another device loop instead.