Re: [PATCH v12 12/17] arm-smmu-v3/sva: Add SVA domain support

Baolu Lu
2022-08-28T13:57:34Z

On 2022/8/26 22:56, Jason Gunthorpe wrote:
> On Fri, Aug 26, 2022 at 08:11:36PM +0800, Lu Baolu wrote:
>
>> +static const struct iommu_domain_ops arm_smmu_sva_domain_ops = {
>> + .set_dev_pasid = arm_smmu_sva_set_dev_pasid,
> Do we want to permit drivers to not allow a SVA domain to be set on a
> RID?
>
> It seems like a weird restriction to me

Conceptually as long as the page table is compatible and user pages are
pinned (or I/O page fault is supported), the device drivers are valid to
set SVA domain to a RID. But I don't see a real use case as far as I can
see.

A reasonable use case is sharing EPT between KVM and IOMMU. That demands
a new type of domain and implements its own .set_dev for page table
attachment.

Best regards,
baolu