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

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Message-ID: <BN9PR11MB527672402F30F701A5EA53028C94A@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Fri, 22 Dec 2023 07:12:36 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: "Liu, Yi L" <yi.l.liu@...el.com>
CC: "Yang, Weijiang" <weijiang.yang@...el.com>, "joro@...tes.org"
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Subject: RE: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain

> 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?