* IOMMU regression in linux-6.18.y
@ 2026-01-21 2:08 Mario Limonciello
2026-01-21 5:26 ` Mario Limonciello
0 siblings, 1 reply; 6+ messages in thread
From: Mario Limonciello @ 2026-01-21 2:08 UTC (permalink / raw)
To: regressions, stable; +Cc: iommu, Hegde, Vasant, Hou, Lizhi
Hi,
Recently I found out that amdxdna stopped working in linux-6.18.4. This
is because of this commit in linux-6.18.y:
commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")
That was originally backported from upstream:
commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")
---
SVA support is a requirement for amdxdna.
The series that this commit came from was part of a larger 8 patch
series, but this was the only commit that was CC'ed to stable.
As a result this is not broken in 6.19-rc, but it is broken in
linux-6.18.y (and presumably any older stable kernels still around that
picked it up).
So there are two options I see:
1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel that
picked it up but has amdxdna)
2) Bring the entire 8 patch series to linux-6.18.y.
This is the entire series (I didn't look up the hashes from mainline,
but they should have all landed):
https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-baolu.lu@linux.intel.com/
What should we do?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: IOMMU regression in linux-6.18.y
2026-01-21 2:08 IOMMU regression in linux-6.18.y Mario Limonciello
@ 2026-01-21 5:26 ` Mario Limonciello
2026-01-21 7:14 ` Baolu Lu
0 siblings, 1 reply; 6+ messages in thread
From: Mario Limonciello @ 2026-01-21 5:26 UTC (permalink / raw)
To: Mario Limonciello, regressions, stable; +Cc: iommu, Hegde, Vasant, Hou, Lizhi
On 1/20/26 8:08 PM, Mario Limonciello wrote:
> Hi,
>
> Recently I found out that amdxdna stopped working in linux-6.18.4. This
> is because of this commit in linux-6.18.y:
>
> commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")
>
> That was originally backported from upstream:
>
> commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")
>
> ---
>
> SVA support is a requirement for amdxdna.
>
> The series that this commit came from was part of a larger 8 patch
> series, but this was the only commit that was CC'ed to stable.
>
> As a result this is not broken in 6.19-rc, but it is broken in
> linux-6.18.y (and presumably any older stable kernels still around that
> picked it up).
>
> So there are two options I see:
>
> 1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel that
> picked it up but has amdxdna)
>
> 2) Bring the entire 8 patch series to linux-6.18.y.
>
> This is the entire series (I didn't look up the hashes from mainline,
> but they should have all landed):
> https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-
> baolu.lu@linux.intel.com/
>
> What should we do?
>
If the decision is to take the remaining commits to 6.18.y to fix this I
did confirm they cleanly cherry pick and build. Here are the hashes.
commit 27bfafac65d8 ("mm: add a ptdesc flag to mark kernel page tables")
commit 977870522af3 ("mm: actually mark kernel page table pages")
commit 412d000346ea ("x86/mm: use 'ptdesc' when freeing PMD pages")
commit 018942956723 ("mm: introduce pure page table freeing function")
commit bf9e4e30f353 ("x86/mm: use pagetable_free()")
commit 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page
tables")
commit e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for
kernel address space")
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: IOMMU regression in linux-6.18.y
2026-01-21 5:26 ` Mario Limonciello
@ 2026-01-21 7:14 ` Baolu Lu
2026-01-21 7:26 ` Greg KH
0 siblings, 1 reply; 6+ messages in thread
From: Baolu Lu @ 2026-01-21 7:14 UTC (permalink / raw)
To: Mario Limonciello, Mario Limonciello, regressions, stable
Cc: iommu, Hegde, Vasant, Hou, Lizhi
On 1/21/26 13:26, Mario Limonciello wrote:
>
>
> On 1/20/26 8:08 PM, Mario Limonciello wrote:
>> Hi,
>>
>> Recently I found out that amdxdna stopped working in linux-6.18.4.
>> This is because of this commit in linux-6.18.y:
>>
>> commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")
>>
>> That was originally backported from upstream:
>>
>> commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")
>>
>> ---
>>
>> SVA support is a requirement for amdxdna.
>>
>> The series that this commit came from was part of a larger 8 patch
>> series, but this was the only commit that was CC'ed to stable.
>>
>> As a result this is not broken in 6.19-rc, but it is broken in
>> linux-6.18.y (and presumably any older stable kernels still around
>> that picked it up).
>>
>> So there are two options I see:
>>
>> 1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel
>> that picked it up but has amdxdna)
>>
>> 2) Bring the entire 8 patch series to linux-6.18.y.
>>
>> This is the entire series (I didn't look up the hashes from mainline,
>> but they should have all landed):
>> https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-
>> baolu.lu@linux.intel.com/
>>
>> What should we do?
>>
>
> If the decision is to take the remaining commits to 6.18.y to fix this I
> did confirm they cleanly cherry pick and build. Here are the hashes.
>
> commit 27bfafac65d8 ("mm: add a ptdesc flag to mark kernel page tables")
> commit 977870522af3 ("mm: actually mark kernel page table pages")
> commit 412d000346ea ("x86/mm: use 'ptdesc' when freeing PMD pages")
> commit 018942956723 ("mm: introduce pure page table freeing function")
> commit bf9e4e30f353 ("x86/mm: use pagetable_free()")
> commit 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page
> tables")
> commit e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for
> kernel address space")
>
Yes. These patches fix a security issue in iommu/sva on x86 and restore
the SVA functionality.
Thanks,
baolu
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: IOMMU regression in linux-6.18.y
2026-01-21 7:14 ` Baolu Lu
@ 2026-01-21 7:26 ` Greg KH
2026-01-21 7:32 ` Baolu Lu
0 siblings, 1 reply; 6+ messages in thread
From: Greg KH @ 2026-01-21 7:26 UTC (permalink / raw)
To: Baolu Lu
Cc: Mario Limonciello, Mario Limonciello, regressions, stable, iommu,
Hegde, Vasant, Hou, Lizhi
On Wed, Jan 21, 2026 at 03:14:42PM +0800, Baolu Lu wrote:
> On 1/21/26 13:26, Mario Limonciello wrote:
> >
> >
> > On 1/20/26 8:08 PM, Mario Limonciello wrote:
> > > Hi,
> > >
> > > Recently I found out that amdxdna stopped working in linux-6.18.4.
> > > This is because of this commit in linux-6.18.y:
> > >
> > > commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")
> > >
> > > That was originally backported from upstream:
> > >
> > > commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")
> > >
> > > ---
> > >
> > > SVA support is a requirement for amdxdna.
> > >
> > > The series that this commit came from was part of a larger 8 patch
> > > series, but this was the only commit that was CC'ed to stable.
> > >
> > > As a result this is not broken in 6.19-rc, but it is broken in
> > > linux-6.18.y (and presumably any older stable kernels still around
> > > that picked it up).
> > >
> > > So there are two options I see:
> > >
> > > 1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel
> > > that picked it up but has amdxdna)
> > >
> > > 2) Bring the entire 8 patch series to linux-6.18.y.
> > >
> > > This is the entire series (I didn't look up the hashes from
> > > mainline, but they should have all landed):
> > > https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-
> > > baolu.lu@linux.intel.com/
> > >
> > > What should we do?
> > >
> >
> > If the decision is to take the remaining commits to 6.18.y to fix this I
> > did confirm they cleanly cherry pick and build. Here are the hashes.
> >
> > commit 27bfafac65d8 ("mm: add a ptdesc flag to mark kernel page tables")
> > commit 977870522af3 ("mm: actually mark kernel page table pages")
> > commit 412d000346ea ("x86/mm: use 'ptdesc' when freeing PMD pages")
> > commit 018942956723 ("mm: introduce pure page table freeing function")
> > commit bf9e4e30f353 ("x86/mm: use pagetable_free()")
> > commit 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page
> > tables")
> > commit e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for
> > kernel address space")
> >
>
> Yes. These patches fix a security issue in iommu/sva on x86 and restore
> the SVA functionality.
So all should be backported? If so, great, but why were they not tagged
as such?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: IOMMU regression in linux-6.18.y
2026-01-21 7:26 ` Greg KH
@ 2026-01-21 7:32 ` Baolu Lu
2026-01-21 14:55 ` Greg KH
0 siblings, 1 reply; 6+ messages in thread
From: Baolu Lu @ 2026-01-21 7:32 UTC (permalink / raw)
To: Greg KH
Cc: Mario Limonciello, Mario Limonciello, regressions, stable, iommu,
Hegde, Vasant, Hou, Lizhi
On 1/21/26 15:26, Greg KH wrote:
> On Wed, Jan 21, 2026 at 03:14:42PM +0800, Baolu Lu wrote:
>> On 1/21/26 13:26, Mario Limonciello wrote:
>>>
>>>
>>> On 1/20/26 8:08 PM, Mario Limonciello wrote:
>>>> Hi,
>>>>
>>>> Recently I found out that amdxdna stopped working in linux-6.18.4.
>>>> This is because of this commit in linux-6.18.y:
>>>>
>>>> commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")
>>>>
>>>> That was originally backported from upstream:
>>>>
>>>> commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")
>>>>
>>>> ---
>>>>
>>>> SVA support is a requirement for amdxdna.
>>>>
>>>> The series that this commit came from was part of a larger 8 patch
>>>> series, but this was the only commit that was CC'ed to stable.
>>>>
>>>> As a result this is not broken in 6.19-rc, but it is broken in
>>>> linux-6.18.y (and presumably any older stable kernels still around
>>>> that picked it up).
>>>>
>>>> So there are two options I see:
>>>>
>>>> 1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel
>>>> that picked it up but has amdxdna)
>>>>
>>>> 2) Bring the entire 8 patch series to linux-6.18.y.
>>>>
>>>> This is the entire series (I didn't look up the hashes from
>>>> mainline, but they should have all landed):
>>>> https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-
>>>> baolu.lu@linux.intel.com/
>>>>
>>>> What should we do?
>>>>
>>>
>>> If the decision is to take the remaining commits to 6.18.y to fix this I
>>> did confirm they cleanly cherry pick and build. Here are the hashes.
>>>
>>> commit 27bfafac65d8 ("mm: add a ptdesc flag to mark kernel page tables")
>>> commit 977870522af3 ("mm: actually mark kernel page table pages")
>>> commit 412d000346ea ("x86/mm: use 'ptdesc' when freeing PMD pages")
>>> commit 018942956723 ("mm: introduce pure page table freeing function")
>>> commit bf9e4e30f353 ("x86/mm: use pagetable_free()")
>>> commit 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page
>>> tables")
>>> commit e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for
>>> kernel address space")
>>>
>>
>> Yes. These patches fix a security issue in iommu/sva on x86 and restore
>> the SVA functionality.
>
> So all should be backported? If so, great, but why were they not tagged
> as such?
Yes, they should be backported. I am sorry; we should have tagged them
at the time we upstreamed them.
>
> thanks,
>
> greg k-h
>
Thanks,
baolu
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: IOMMU regression in linux-6.18.y
2026-01-21 7:32 ` Baolu Lu
@ 2026-01-21 14:55 ` Greg KH
0 siblings, 0 replies; 6+ messages in thread
From: Greg KH @ 2026-01-21 14:55 UTC (permalink / raw)
To: Baolu Lu
Cc: Mario Limonciello, Mario Limonciello, regressions, stable, iommu,
Hegde, Vasant, Hou, Lizhi
On Wed, Jan 21, 2026 at 03:32:42PM +0800, Baolu Lu wrote:
> On 1/21/26 15:26, Greg KH wrote:
> > On Wed, Jan 21, 2026 at 03:14:42PM +0800, Baolu Lu wrote:
> > > On 1/21/26 13:26, Mario Limonciello wrote:
> > > >
> > > >
> > > > On 1/20/26 8:08 PM, Mario Limonciello wrote:
> > > > > Hi,
> > > > >
> > > > > Recently I found out that amdxdna stopped working in linux-6.18.4.
> > > > > This is because of this commit in linux-6.18.y:
> > > > >
> > > > > commit c341dee80b5d ("iommu: disable SVA when CONFIG_X86 is set")
> > > > >
> > > > > That was originally backported from upstream:
> > > > >
> > > > > commit 72f98ef9a4be ("iommu: disable SVA when CONFIG_X86 is set")
> > > > >
> > > > > ---
> > > > >
> > > > > SVA support is a requirement for amdxdna.
> > > > >
> > > > > The series that this commit came from was part of a larger 8 patch
> > > > > series, but this was the only commit that was CC'ed to stable.
> > > > >
> > > > > As a result this is not broken in 6.19-rc, but it is broken in
> > > > > linux-6.18.y (and presumably any older stable kernels still around
> > > > > that picked it up).
> > > > >
> > > > > So there are two options I see:
> > > > >
> > > > > 1) Revert c341dee80b5d in linux-6.18.y (and any other stable kernel
> > > > > that picked it up but has amdxdna)
> > > > >
> > > > > 2) Bring the entire 8 patch series to linux-6.18.y.
> > > > >
> > > > > This is the entire series (I didn't look up the hashes from
> > > > > mainline, but they should have all landed):
> > > > > https://lore.kernel.org/linux-iommu/20251022082635.2462433-1-
> > > > > baolu.lu@linux.intel.com/
> > > > >
> > > > > What should we do?
> > > > >
> > > >
> > > > If the decision is to take the remaining commits to 6.18.y to fix this I
> > > > did confirm they cleanly cherry pick and build. Here are the hashes.
> > > >
> > > > commit 27bfafac65d8 ("mm: add a ptdesc flag to mark kernel page tables")
> > > > commit 977870522af3 ("mm: actually mark kernel page table pages")
> > > > commit 412d000346ea ("x86/mm: use 'ptdesc' when freeing PMD pages")
> > > > commit 018942956723 ("mm: introduce pure page table freeing function")
> > > > commit bf9e4e30f353 ("x86/mm: use pagetable_free()")
> > > > commit 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page
> > > > tables")
> > > > commit e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for
> > > > kernel address space")
> > > >
> > >
> > > Yes. These patches fix a security issue in iommu/sva on x86 and restore
> > > the SVA functionality.
> >
> > So all should be backported? If so, great, but why were they not tagged
> > as such?
>
> Yes, they should be backported. I am sorry; we should have tagged them
> at the time we upstreamed them.
Ok, all now queued up, thanks.
greg k-h
^ permalink raw reply [flat|nested] 6+ messages in thread
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2026-01-21 2:08 IOMMU regression in linux-6.18.y Mario Limonciello
2026-01-21 5:26 ` Mario Limonciello
2026-01-21 7:14 ` Baolu Lu
2026-01-21 7:26 ` Greg KH
2026-01-21 7:32 ` Baolu Lu
2026-01-21 14:55 ` Greg KH
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