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

[Baolu Lu <baolu.lu@linux.intel.com>]

On 10/18/25 02:26, Vinicius Costa Gomes wrote:
> Dave Hansen<dave.hansen@intel.com> writes:
> 
>> On 10/17/25 07:01, Jason Gunthorpe wrote:
>>>>> 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?
>>> IDK, the only SVA user on x86 I know is IDXD, so if you do the above
>>> plan you break IDXD in all stable kernels. Doesn't sound OK?
>> Vinicius, any thoughts on this?
>>
> This won't break IDXD exactly/totally, it would cause it to be
> impossible for users to create shared DSA/IAA workqueues (which are the
> nicer ones to use), and it will cause the driver to print some not happy
> messages in the kernel logs. The in-kernel users of IDXD (iaa_crypto for
> zswap, for example) will continue to work.
> 
> In short, I am not happy, but I think it's workable, even better if
> there are alternatives in case people complain.

Okay, so I will add an extra patch to disable SVA for x86 arch and re-
enable it after the kernel page table free callback is done.

Thanks,
baolu