Re: [PATCH v2 12/16] KVM: arm64: Implement AT S1PIE support

[Marc Zyngier <maz@kernel.org>]

Hi Joey,

Thanks for having a look.

On Thu, 05 Sep 2024 14:58:20 +0100,
Joey Gouly <joey.gouly@arm.com> wrote:
> 
> Hello Marc!
> 
> >  static void compute_s1_permissions(struct kvm_vcpu *vcpu, u32 op,
> >  				   struct s1_walk_info *wi,
> >  				   struct s1_walk_result *wr,
> >  				   struct s1_perms *s1p)
> >  {
> > -	compute_s1_direct_permissions(vcpu, wi, wr, s1p);
> > +	if (!s1pie_enabled(vcpu, wi->regime))
> > +		compute_s1_direct_permissions(vcpu, wi, wr, s1p);
> > +	else
> > +		compute_s1_indirect_permissions(vcpu, wi, wr, s1p);
> > +
> >  	compute_s1_hierarchical_permissions(vcpu, wi, wr, s1p);
> 
> Is this (and the previous patch to split this up) right?
> 
> Looking at this from the ARM ARM (ARM DDI 0487K.a):
> 
> 	R JHSVW If Indirect permissions are used, then hierarchical
> 	permissions are disabled and TCR_ELx.HPDn are RES 1.

Odd. I was convinced that it was when S1POE is enabled that HPs were
disabled. But you are absolutely right, and it is once more proven
that I can't read. Oh well.

Not to worry, I've since found other issues with this series. I have
forgotten the patch dealing with the fast path on another branch, and
since decided that TCR2_EL2 needed extra care to cope with individual
features being disabled.

The rework is still useful, as I'm looking at POE as well, but I need
to hoist the HP stuff up a notch.

I'll repost things once I've sorted these things up.

Thanks again,

	M.

-- 
Without deviation from the norm, progress is not possible.