[RFC PATCH v3 4/5] iommu/arm-smmu-v3-iommufd: Use KVM VMID for s2 stage

[Jason Gunthorpe]

On Thu, Mar 20, 2025 at 09:30:45AM +0000, Shameerali Kolothum Thodi wrote:
> > Isn't kvm_get_kvm_safe() in modular KVM code most of the time? You can't
> > call it like this right?
> 
> I think it is safe since KVM is not modular for ARM64. And that is one of the
> reasons I thought I will hold the KVM reference here as we don't have to go
> through the symbol_get/put calls here. Also IOMMUFD is not using the kvm
> pointer at the moment. Probably I should add some comments in IOMMUFD
> to make it clear.

Oh I didn't know that.. Interesting simplification

> > That more closely matches how this will eventually work when the VMID
> > allocation is properly made to be local to the viommu.
> 
> Ok. Will update.

You should also block creating a VIOMMU without a KVM for the same
reason.. Really isolate the S2 to only being usable with the KVM
shared VMID.

Jason