linux-kernel - RE: [PATCH v14 00/13] SMMUv3 Nested Stage Setup (IOMMU part)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BY5PR12MB37642B9AC7E5D907F5A664F6B3459@BY5PR12MB3764.namprd12.prod.outlook.com>
Date:   Fri, 23 Apr 2021 17:58:23 +0000
From:   Krishna Reddy <vdumpa@...dia.com>
To:     Sumit Gupta <sumitg@...dia.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>
CC:     "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "eric.auger.pro@...il.com" <eric.auger.pro@...il.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "jiangkunkun@...wei.com" <jiangkunkun@...wei.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "lushenming@...wei.com" <lushenming@...wei.com>,
        "maz@...nel.org" <maz@...nel.org>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "tn@...ihalf.com" <tn@...ihalf.com>,
        "vivek.gautam@....com" <vivek.gautam@....com>,
        Vikram Sethi <vsethi@...dia.com>,
        "wangxingang5@...wei.com" <wangxingang5@...wei.com>,
        "will@...nel.org" <will@...nel.org>,
        "zhangfei.gao@...aro.org" <zhangfei.gao@...aro.org>,
        "zhukeqian1@...wei.com" <zhukeqian1@...wei.com>,
        Sachin Nikam <Snikam@...dia.com>,
        Bibek Basu <bbasu@...dia.com>,
        Shanker Donthineni <sdonthineni@...dia.com>,
        Vikram Sethi <vsethi@...dia.com>
Subject: RE: [PATCH v14 00/13] SMMUv3 Nested Stage Setup (IOMMU part)

>> Did that patch cause any issue, or is it just not needed on your system?
>> It fixes an hypothetical problem with the way ATS is implemented. 
>> Maybe I actually observed it on an old software model, I don't 
>> remember. Either way it's unlikely to go upstream but I'd like to know 
>> if I should drop it from my tree.

> Had to revert same patch "mm: notify remote TLBs when dirtying a PTE" to
> avoid below crash[1]. I am not sure about the cause yet.

I have noticed this issue earlier with patch pointed here and root caused the issue as below.
It happens after vfio_mmap request from QEMU for the PCIe device and during the access of VA when
PTE access flags are updated. 

kvm_mmu_notifier_change_pte() --> kvm_set_spte_hve() --> kvm_set_spte_hva() --> clean_dcache_guest_page()

The validation model doesn't have FWB capability supported.
__clean_dcache_guest_page() attempts to perform dcache flush on pcie bar address(not a valid_pfn()) through page_address(),
which doesn't have page table mapping and leads to exception.

I have worked around the issue by filtering out the request if the pfn is not valid in  __clean_dcache_guest_page(). 
As the patch wasn't posted in the community, reverted it as well.

-KR