linux-kernel - Re: [PATCH] KVM: arm64: Expose S1PIE to guests

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Message-ID: <20241008093104.GA2623892@e124191.cambridge.arm.com>
Date: Tue, 8 Oct 2024 10:31:04 +0100
From: Joey Gouly <joey.gouly@....com>
To: Mark Brown <broonie@...nel.org>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: arm64: Expose S1PIE to guests

Hi,

On Sat, Oct 05, 2024 at 12:19:37AM +0100, Mark Brown wrote:
> Prior to commit 70ed7238297f ("KVM: arm64: Sanitise ID_AA64MMFR3_EL1")
> we just exposed the santised view of ID_AA64MMFR3_EL1 to guests, meaning
> that they saw both TCRX and S1PIE if present on the host machine. That
> commit added VMM control over the contents of the register and exposed
> S1POE but removed S1PIE, meaning that the extension is no longer visible
> to guests. Reenable support for S1PIE with VMM control.
> 
> Fixes: 70ed7238297f ("KVM: arm64: Sanitise ID_AA64MMFR3_EL1")
> Signed-off-by: Mark Brown <broonie@...nel.org>
> ---
>  arch/arm64/kvm/sys_regs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index dad88e31f9537fe02e28b117d6a740f15572e0ba..d48f89ad6aa7139078e7991ce6c8ebc4a0543551 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1550,7 +1550,8 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
>  		val &= ~ID_AA64MMFR2_EL1_CCIDX_MASK;
>  		break;
>  	case SYS_ID_AA64MMFR3_EL1:
> -		val &= ID_AA64MMFR3_EL1_TCRX | ID_AA64MMFR3_EL1_S1POE;
> +		val &= ID_AA64MMFR3_EL1_TCRX | ID_AA64MMFR3_EL1_S1POE |
> +			ID_AA64MMFR3_EL1_S1PIE;
>  		break;
>  	case SYS_ID_MMFR4_EL1:
>  		val &= ~ARM64_FEATURE_MASK(ID_MMFR4_EL1_CCIDX);
> @@ -2433,6 +2434,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  					ID_AA64MMFR2_EL1_NV |
>  					ID_AA64MMFR2_EL1_CCIDX)),
>  	ID_WRITABLE(ID_AA64MMFR3_EL1, (ID_AA64MMFR3_EL1_TCRX	|
> +				       ID_AA64MMFR3_EL1_S1PIE   |
>  				       ID_AA64MMFR3_EL1_S1POE)),
>  	ID_SANITISED(ID_AA64MMFR4_EL1),
>  	ID_UNALLOCATED(7,5),
> 
> ---

Sorry, silly mistake by me.

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

Thanks,
Joey