Re: [PATCH v2 1/7] KVM: x86/mmu: Track if shadow MMU active

[Sean Christopherson <seanjc@google.com>]

On Tue, May 04, 2021, Paolo Bonzini wrote:
> On 04/05/21 21:55, Sean Christopherson wrote:
> > But, I think we we can avoid bikeshedding by simply eliminating this flag.  More
> > in later patches.
> 
> Are you thinking of checking slot->arch.rmap[0] directly?  That should work
> indeed.
> 
> > > -	kvm_mmu_init_tdp_mmu(kvm);
> > > +	if (!kvm_mmu_init_tdp_mmu(kvm))
> > > +		activate_shadow_mmu(kvm);
> > Doesn't come into play yet, but I would strongly prefer to open code setting the
> > necessary flag instead of relying on the helper to never fail.
> > 
> 
> You mean
> 
> kvm->arch.shadow_mmu_active = !kvm_mmu_init_tdp_mmu(kvm);
> 
> (which would assign to alloc_memslot_rmaps instead if shadow_mmu_active is
> removed)?  That makes sense.

Ya, that or:

	if (kvm_mmu_init_tdp_mmu(kvm))
		kvm->arch.memslots_have_rmaps = true;

I don't have a preference between the two variants.