Re: [RFC PATCH 0/8] hw/arm/smmuv3-accel: Support AUTO properties

[Eric Auger <eric.auger@redhat.com>]

On 3/11/26 6:55 PM, Nathan Chen wrote:
>
>
> On 3/11/2026 10:43 AM, Eric Auger wrote:
>>
>> On 3/9/26 8:21 PM, Nathan Chen wrote:
>>> Hi,
>>>
>>> This series introduces support for specifying 'auto' for arm-smmuv3
>>> accelerated mode's ATS, RIL, SSIDSIZE, and OAS feature properties.
>>> When set to 'auto', these feature values are derived directly from
>>> host IOMMU capabilities, avoiding the need for management layers to
>>> introspect host settings.
>>>
>>> Accelerated SMMUv3 Address Translation Services support is derived
>>> from IDR0, Range Invalidation support is derived from IDR3, Substream
>>> ID size is derived from IDR1, and output address space is derived from
>>> IDR5.
>>>
>>> Additionally, an OnOffAuto "ats" property is added for vfio-pci
>>> devices,
>>> where setting 'auto' detects the per-device presence of
>>> IOMMU_HW_CAP_PCI_ATS_NOT_SUPPORTED from the kernel, and the ATS cap can
>>> be advertised or hidden by setting 'on' or 'off'. This is dependent
>>> on Shameer's recent kernel series for reporting effective ATS support
>>> status [0].
>>>
>>> The default values are set to 'auto' for all properties.
>>>
>>> A complete branch can be found here:
>>> https://github.com/NathanChenNVIDIA/qemu/tree/smmuv3-accel-auto
>> I have just noticed we are missing documentation for smmuv3 accel
>> options in
>>
>> qemu-options.hx
>>
>> At the moment we just have:
>>
>> ``-device arm-smmuv3,primary-bus=id``
>>      This is only supported by ``-machine virt`` (ARM).
>>
>>      ``primary-bus=id``
>>          Accepts either the default root complex (pcie.0) or a
>>          pxb-pcie based root complex.
>
> I will add a commit to include documentation for the smmuv3 accel
> options in the next refresh. 

Great. Thanks!

>
> Thanks,
> Nathan
>