Re: [PATCH v5 34/37] KVM: arm64: Disable hierarchical permissions when POE is enabled

[Joey Gouly <joey.gouly@arm.com>]

On Wed, Oct 23, 2024 at 03:53:42PM +0100, Marc Zyngier wrote:
> The hierarchical permissions must be disabled when POE is enabled
> in the translation regime used for a given table walk.
> 
> We store the two enable bits in the s1_walk_info structure so that
> they can be retrieved down the line, as they will be useful.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

> ---
>  arch/arm64/kvm/at.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
> index ef1643faedeb4..8d1dc6327ec5b 100644
> --- a/arch/arm64/kvm/at.c
> +++ b/arch/arm64/kvm/at.c
> @@ -24,6 +24,8 @@ struct s1_walk_info {
>  	unsigned int		txsz;
>  	int 	     		sl;
>  	bool	     		hpd;
> +	bool			e0poe;
> +	bool			poe;
>  	bool	     		be;
>  	bool	     		s2;
>  };
> @@ -110,6 +112,34 @@ static bool s1pie_enabled(struct kvm_vcpu *vcpu, enum trans_regime regime)
>  	}
>  }
>  
> +static void compute_s1poe(struct kvm_vcpu *vcpu, struct s1_walk_info *wi)
> +{
> +	u64 val;
> +
> +	if (!kvm_has_s1poe(vcpu->kvm)) {
> +		wi->poe = wi->e0poe = false;
> +		return;
> +	}
> +
> +	switch (wi->regime) {
> +	case TR_EL2:
> +	case TR_EL20:
> +		val = vcpu_read_sys_reg(vcpu, TCR2_EL2);
> +		wi->poe = val & TCR2_EL2_POE;
> +		wi->e0poe = (wi->regime == TR_EL20) && (val & TCR2_EL2_E0POE);
> +		break;
> +	case TR_EL10:
> +		if (__vcpu_sys_reg(vcpu, HCRX_EL2) & HCRX_EL2_TCR2En) {
> +			wi->poe = wi->e0poe = false;
> +			return;
> +		}
> +
> +		val = __vcpu_sys_reg(vcpu, TCR2_EL1);
> +		wi->poe = val & TCR2_EL1x_POE;
> +		wi->e0poe = val & TCR2_EL1x_E0POE;
> +	}
> +}
> +
>  static int setup_s1_walk(struct kvm_vcpu *vcpu, u32 op, struct s1_walk_info *wi,
>  			 struct s1_walk_result *wr, u64 va)
>  {
> @@ -206,6 +236,12 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, u32 op, struct s1_walk_info *wi,
>  	/* R_JHSVW */
>  	wi->hpd |= s1pie_enabled(vcpu, wi->regime);
>  
> +	/* Do we have POE? */
> +	compute_s1poe(vcpu, wi);
> +
> +	/* R_BVXDG */
> +	wi->hpd |= (wi->poe || wi->e0poe);
> +
>  	/* Someone was silly enough to encode TG0/TG1 differently */
>  	if (va55) {
>  		wi->txsz = FIELD_GET(TCR_T1SZ_MASK, tcr);
> -- 
> 2.39.2
>