Re: [PATCH 09/10] KVM: arm64: Handle PIR{,E0}_EL2 traps

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

On Tue, Aug 13, 2024 at 03:47:37PM +0100, Marc Zyngier wrote:
> Add the FEAT_S1PIE EL2 registers the sysreg descriptor array so that
> they can be handled as a trap.
> 
> Access to these registers is conditionned on ID_AA64MMFR3_EL1.S1PIE
> being advertised.
> 
> Similarly to other other changes, PIRE0_EL2 is guaranteed to trap
> thanks to the D22677 update to the architecture..
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  arch/arm64/kvm/sys_regs.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 52250db3c122..a5f604e24e05 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -346,6 +346,18 @@ static bool access_rw(struct kvm_vcpu *vcpu,
>  	return true;
>  }
>  
> +static bool check_s1pie_access_rw(struct kvm_vcpu *vcpu,
> +				  struct sys_reg_params *p,
> +				  const struct sys_reg_desc *r)
> +{
> +	if (!kvm_has_feat(vcpu->kvm, ID_AA64MMFR3_EL1, S1PIE, IMP)) {
> +		kvm_inject_undefined(vcpu);
> +		return false;
> +	}
> +
> +	return access_rw(vcpu, p, r);
> +}
> +
>  /*
>   * See note at ARMv7 ARM B1.14.4 (TL;DR: S/W ops are not easily virtualized).
>   */
> @@ -2827,6 +2839,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	EL2_REG(HPFAR_EL2, access_rw, reset_val, 0),
>  
>  	EL2_REG(MAIR_EL2, access_rw, reset_val, 0),
> +	EL2_REG(PIRE0_EL2, check_s1pie_access_rw, reset_val, 0),
> +	EL2_REG(PIR_EL2, check_s1pie_access_rw, reset_val, 0),
>  	EL2_REG(AMAIR_EL2, access_rw, reset_val, 0),
>  
>  	EL2_REG(VBAR_EL2, access_rw, reset_val, 0),

I think we should also use this for PIR_EL1 / PIRE0_EL1? We have NULL for their access field.

	{ SYS_DESC(SYS_PIR_EL1), NULL, reset_unknown, PIR_EL1 },