linux-kernel - Re: [PATCH v6 0/7] Fix stale IOTLB entries for kernel address space

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Message-ID: <11cad2be-9402-4d45-8d2b-c92d8962edfc@linux.intel.com>
Date: Fri, 17 Oct 2025 09:42:10 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Dave Hansen <dave.hansen@...el.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Kevin Tian <kevin.tian@...el.com>,
 Jason Gunthorpe <jgg@...dia.com>, Jann Horn <jannh@...gle.com>,
 Vasant Hegde <vasant.hegde@....com>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Alistair Popple <apopple@...dia.com>, Peter Zijlstra <peterz@...radead.org>,
 Uladzislau Rezki <urezki@...il.com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>,
 Andy Lutomirski <luto@...nel.org>, Yi Lai <yi1.lai@...el.com>,
 David Hildenbrand <david@...hat.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>,
 Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
 Michal Hocko <mhocko@...nel.org>, Matthew Wilcox <willy@...radead.org>,
 iommu@...ts.linux.dev, security@...nel.org, x86@...nel.org,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 0/7] Fix stale IOTLB entries for kernel address space

On 10/15/25 23:55, Dave Hansen wrote:
>>> Only [7/7] has acc:stable, even though that patch is not at all
>>> backportable.  Please give some thought and suggestions regarding
>>> whether you think we should backport this into earlier kernels.
>> Yes. We should backport this series to stable kernels.
>>
>>> If "yes" then the size and scope of the series looks problematic.  Is
>>> it possible to put together something simple and expedient just to plug
>>> the hole in older kernels?
>> Squashing some patches is one way. But would it be workable to backport
>> this series manually? Say, could we send a pull request to the stable
>> mailing list after this series has landed?
> I honestly think we should just disable SVA in old kernels at compile
> time, or at least default it to be disabled at runtime. That's the
> simplest thing.
> 
> The other alternative is to have arch_vmap_pmd_supported() return false
> when SVA is active, or maybe when it's supported on the platform.
> 
> Either of those are 10-ish lines of code and easy to backport.

Hi iommu folks, any insights on this?

Thanks,
baolu