Re: [PATCH 22/25] KVM: arm64: Make PIR{,E0}_EL1 UNDEF if S1PIE is not advertised to the guest

[Marc Zyngier <maz@kernel.org>]

On Tue, 23 Jan 2024 11:48:10 +0000,
Joey Gouly <joey.gouly@arm.com> wrote:
> 
> Hello,
> 
> On Mon, Jan 22, 2024 at 08:18:49PM +0000, Marc Zyngier wrote:
> > As part of the ongoing effort to honor the guest configuration,
> > add the necessary checks to make PIR_EL1 and co UNDEF if not
> > advertised to the guest, and avoid context switching them.
> > 
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
> > ---
> >  arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 15 ++++++++++++++-
> >  arch/arm64/kvm/sys_regs.c                  |  4 ++++
> >  2 files changed, 18 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
> > index bb6b571ec627..b34743292ca7 100644
> > --- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
> > +++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
> > @@ -37,6 +37,19 @@ static inline bool ctxt_has_mte(struct kvm_cpu_context *ctxt)
> >  	return kvm_has_mte(kern_hyp_va(vcpu->kvm));
> >  }
> >  
> > +static inline bool ctxt_has_s1pie(struct kvm_cpu_context *ctxt)
> > +{
> > +	struct kvm_vcpu *vcpu = ctxt->__hyp_running_vcpu;
> > +
> > +	if (!cpus_have_final_cap(ARM64_HAS_S1PIE))
> > +		return false;
> > +
> > +	if (!vcpu)
> > +		vcpu = container_of(ctxt, struct kvm_vcpu, arch.ctxt);
> > +
> > +	return kvm_has_feat(kern_hyp_va(vcpu->kvm), ID_AA64MMFR3_EL1, S1PIE, IMP);
> > +}
> > +
> >  static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
> >  {
> >  	ctxt_sys_reg(ctxt, SCTLR_EL1)	= read_sysreg_el1(SYS_SCTLR);
> > @@ -55,7 +68,7 @@ static inline void __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
> >  	ctxt_sys_reg(ctxt, CONTEXTIDR_EL1) = read_sysreg_el1(SYS_CONTEXTIDR);
> >  	ctxt_sys_reg(ctxt, AMAIR_EL1)	= read_sysreg_el1(SYS_AMAIR);
> >  	ctxt_sys_reg(ctxt, CNTKCTL_EL1)	= read_sysreg_el1(SYS_CNTKCTL);
> > -	if (cpus_have_final_cap(ARM64_HAS_S1PIE)) {
> > +	if (ctxt_has_s1pie(ctxt)) {
> >  		ctxt_sys_reg(ctxt, PIR_EL1)	= read_sysreg_el1(SYS_PIR);
> >  		ctxt_sys_reg(ctxt, PIRE0_EL1)	= read_sysreg_el1(SYS_PIRE0);
> >  	}
> 
> Missing the corresponding change in __sysreg_restore_el1_state().

Gah. Thanks for spotting it. I'm pretty sure I had it at some point,
and somehow lost it. Probably on another machine somewhere...

Cheers,

	M.

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