Re: RFC KVM: arm64: selftest: stage 2 mapping helpers

[Sean Christopherson <seanjc@google.com>]

On Wed, Oct 22, 2025, Yosry Ahmed wrote:
> On Wed, Oct 22, 2025 at 10:47:15AM -0700, Oliver Upton wrote:
> > On Wed, Oct 22, 2025 at 04:57:16PM +0000, Yosry Ahmed wrote:
> > > On Wed, Oct 22, 2025 at 06:34:58AM -0700, Sean Christopherson wrote:
> > IOW, the starting point for us is fine-grained control over potentially
> > multiple stage-2 MMUs with modal descriptor fields that change meaning
> > based on the current MMU context.
> > 
> > > > I.e. if we envision any arch-agnositic tests that can do nested things,
> > > > now's the time.  E.g. running dirty logging tests in L2 maybe?
> > 
> > We can just as easily implement an agnostic wrapper after the fact;
> > enabling architectural validation of the arm64 nested implementation is
> > the highest priority at the moment for us.
> 
> Oh 100%, I was not suggesting that we need to do this now, not sure if
> Sean was.

I was maybe 60% suggesting that? :-)

But it sounds like the underlying x86 and arm64 details are going to be much more
different than I was anticipating, so I'm a-ok punting for now.  E.g. I was thinking
we'd want a common kvm_mmu_arch or kvm_stage2_arch, but trying to implement such
structures without a concrete use case would likely be painful/ugly.