Re: [PATCH 05/22] KVM: arm64: nv: Pass an access descriptor for stage-2 walks

[Leonardo Bras <leo.bras@arm.com>]

On Mon, Sep 21, 2026 at 02:45:58PM -0700, Oliver Upton wrote:
> On Mon, Sep 21, 2026 at 06:28:50PM +0100, Leonardo Bras wrote:
> > > @@ -1642,9 +1655,11 @@ int __kvm_at_s12(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
> > >  		return 0;
> > >  
> > >  	/* Do the stage-2 translation */
> > > -	ipa = (par & GENMASK_ULL(47, 12)) | (vaddr & GENMASK_ULL(11, 0));
> > > +	access.type = WALK_ACCESS_AT;
> > > +	access.ia = (par & GENMASK_ULL(47, 12)) | (vaddr & GENMASK_ULL(11, 0));
> > 
> > What does this mask represent?
> 
> Keep in mind, this is pre-existing code... This mask is taking the GFN
> from the output address of stage-1 translation and using it as the input
> for stage-2.
> 
> Keep in mind nested only supports up to 48 bits of PA space.

Humm, I see.
Maybe adding a define for that bitmask would be a better idea, then, as a 
new define could make the limitation clear, and even be easier to change if 
nested gets to support more than 48 bits of PA space.

> 
> > 
> > IIUC, in general terms most of the changes are adapting the typing on 
> > kvm_walk_nested_s2() & co to make use of the new struct kvm_walk_access 
> > instead of just a PA.
> > 
> > I also see that flags & write are also added here, but not used anywhere.
> > Maybe it would  be worth moving them to the patch that makes use of them, 
> > instead leaving them here?
> 
> I can do that
> 

Awesome, thanks!
Leo