linux-kernel - RE: [PATCH 2/2] iommu/vt-d: Fix checks in pgtable

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Message-ID: <SJ0PR11MB67447D03F5E78EFDB570C60F924D2@SJ0PR11MB6744.namprd11.prod.outlook.com>
Date: Wed, 23 Oct 2024 07:48:10 +0000
From: "Duan, Zhenzhong" <zhenzhong.duan@...el.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>, "iommu@...ts.linux.dev"
	<iommu@...ts.linux.dev>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: "dwmw2@...radead.org" <dwmw2@...radead.org>, "joro@...tes.org"
	<joro@...tes.org>, "will@...nel.org" <will@...nel.org>,
	"robin.murphy@....com" <robin.murphy@....com>, "Peng, Chao P"
	<chao.p.peng@...el.com>, Kyung Min Park <kyung.min.park@...el.com>
Subject: RE: [PATCH 2/2] iommu/vt-d: Fix checks in pgtable_walk()



>-----Original Message-----
>From: Baolu Lu <baolu.lu@...ux.intel.com>
>Subject: Re: [PATCH 2/2] iommu/vt-d: Fix checks in pgtable_walk()
>
>On 2024/10/23 13:16, Duan, Zhenzhong wrote:
>>> -----Original Message-----
>>> From: Baolu Lu<baolu.lu@...ux.intel.com>
>>> Sent: Wednesday, October 23, 2024 12:50 PM
>>> Subject: Re: [PATCH 2/2] iommu/vt-d: Fix checks in pgtable_walk()
>>>
>>> On 2024/10/22 17:50, Zhenzhong Duan wrote:
>>>> It's not accurate to dump super page as non-present page,
>>>> meanwhile bit7 in first level page table entry is PAT bit,
>>> Can you please explain how the 'bit7 in first level page table entry' is
>>> relevant to the changes made in this patch?
>> When iterate to level 1, it is leaf page table entry, bit 7 is PAT bit instead of PS
>bit.
>> dma_pte_superpage(pte) may return true, then " PTE not present at level 1"
>may
>> be printed out.
>
>I see. Thank you!
>
>If you have a new version, can you please make it a bit clearer? My
>understanding is that dma_pte_superpage(pte) should not check against
>the leaf page table entries, right?

Right, will do.

Thanks
Zhenzhong