Re: [PATCH v2 17/19] iommu/arm-smmu-v3: Add arm_smmu_viommu_cache_invalidate

Baolu Lu
2024-09-11T08:19:12Z

On 2024/9/11 16:17, Tian, Kevin wrote:
>> If a VMID for an S2 hwpt is valid on physical IOMMU A but has already
>> been allocated for another purpose on physical IOMMU B, how can it be
>> shared across both IOMMUs? Or the VMID is allocated globally?
>>
> I'm not sure that's a problem. The point is that each vIOMMU object
> will get a VMID from the SMMU which it's associated to (assume
> one vIOMMU cannot span multiple SMMU). Whether that VMID
> is globally allocated or per-SMMU is the policy in the SMMU driver.
>
> It's the driver's responsibility to ensure not using a conflicting VMID
> when creating an vIOMMU instance.

Make sense.

Thanks,
baolu