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From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Quentin Perret <qperret@google.com>,
	Will Deacon <will@kernel.org>, Fuad Tabba <tabba@google.com>
Subject: Re: [PATCH 02/17] arm64: Add KVM_HVHE capability and has_hvhe() predicate
Date: Thu, 1 Jun 2023 07:01:50 +0000	[thread overview]
Message-ID: <ZHhCXm4k9zEOwPtV@linux.dev> (raw)
In-Reply-To: <20221020090727.3669908-3-maz@kernel.org>

On Thu, Oct 20, 2022 at 10:07:12AM +0100, Marc Zyngier wrote:
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index a3959e9f7d55..efac89c4c548 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1932,6 +1932,15 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
>  		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
>  }
>  
> +static bool hvhe_possible(const struct arm64_cpu_capabilities *entry,
> +			  int __unused)
> +{
> +	u64 val;
> +
> +	val = arm64_sw_feature_override.val & arm64_sw_feature_override.mask;
> +	return cpuid_feature_extract_unsigned_field(val, ARM64_SW_FEATURE_OVERRIDE_HVHE);
> +}

Does this need to test ID_AA64MMFR1_EL1.VH as well? Otherwise I don't
see what would stop us from attempting hVHE on a system with asymmetric
support for VHE, as the software override was only evaluated on the boot
CPU.

> +
>  #ifdef CONFIG_ARM64_PAN
>  static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused)
>  {
> @@ -2642,6 +2651,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
>  		.matches = has_cpuid_feature,
>  		.cpu_enable = cpu_trap_el0_impdef,
>  	},
> +	{
> +		.desc = "VHE for hypervisor only",
> +		.capability = ARM64_KVM_HVHE,
> +		.type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> +		.matches = hvhe_possible,
> +	},
>  	{},
>  };
>  
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index f1c0347ec31a..cee2be85b89b 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -43,6 +43,7 @@ HAS_TLB_RANGE
>  HAS_VIRT_HOST_EXTN
>  HAS_WFXT
>  HW_DBM
> +KVM_HVHE
>  KVM_PROTECTED_MODE
>  MISMATCHED_CACHE_TYPE
>  MTE
> -- 
> 2.34.1
> 

-- 
Thanks,
Oliver

WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Quentin Perret <qperret@google.com>,
	Will Deacon <will@kernel.org>, Fuad Tabba <tabba@google.com>
Subject: Re: [PATCH 02/17] arm64: Add KVM_HVHE capability and has_hvhe() predicate
Date: Thu, 1 Jun 2023 07:01:50 +0000	[thread overview]
Message-ID: <ZHhCXm4k9zEOwPtV@linux.dev> (raw)
In-Reply-To: <20221020090727.3669908-3-maz@kernel.org>

On Thu, Oct 20, 2022 at 10:07:12AM +0100, Marc Zyngier wrote:
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index a3959e9f7d55..efac89c4c548 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1932,6 +1932,15 @@ static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
>  		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
>  }
>  
> +static bool hvhe_possible(const struct arm64_cpu_capabilities *entry,
> +			  int __unused)
> +{
> +	u64 val;
> +
> +	val = arm64_sw_feature_override.val & arm64_sw_feature_override.mask;
> +	return cpuid_feature_extract_unsigned_field(val, ARM64_SW_FEATURE_OVERRIDE_HVHE);
> +}

Does this need to test ID_AA64MMFR1_EL1.VH as well? Otherwise I don't
see what would stop us from attempting hVHE on a system with asymmetric
support for VHE, as the software override was only evaluated on the boot
CPU.

> +
>  #ifdef CONFIG_ARM64_PAN
>  static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused)
>  {
> @@ -2642,6 +2651,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
>  		.matches = has_cpuid_feature,
>  		.cpu_enable = cpu_trap_el0_impdef,
>  	},
> +	{
> +		.desc = "VHE for hypervisor only",
> +		.capability = ARM64_KVM_HVHE,
> +		.type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
> +		.matches = hvhe_possible,
> +	},
>  	{},
>  };
>  
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index f1c0347ec31a..cee2be85b89b 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -43,6 +43,7 @@ HAS_TLB_RANGE
>  HAS_VIRT_HOST_EXTN
>  HAS_WFXT
>  HW_DBM
> +KVM_HVHE
>  KVM_PROTECTED_MODE
>  MISMATCHED_CACHE_TYPE
>  MTE
> -- 
> 2.34.1
> 

-- 
Thanks,
Oliver

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-06-01  7:01 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-20  9:07 [PATCH 00/17] KVM: arm64: Allow using VHE in the nVHE hypervisor Marc Zyngier
2022-10-20  9:07 ` Marc Zyngier
2022-10-20  9:07 ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 01/17] arm64: Turn kaslr_feature_override into a generic SW feature override Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 02/17] arm64: Add KVM_HVHE capability and has_hvhe() predicate Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2023-06-01  7:01   ` Oliver Upton [this message]
2023-06-01  7:01     ` Oliver Upton
2022-10-20  9:07 ` [PATCH 03/17] arm64: Don't enable VHE for the kernel if OVERRIDE_HVHE is set Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 04/17] arm64: Prevent the use of is_kernel_in_hyp_mode() in hypervisor code Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 05/17] arm64: Allow EL1 physical timer access when running VHE Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 06/17] arm64: Use CPACR_EL1 format to set CPTR_EL2 when E2H is set Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 07/17] KVM: arm64: Elide kern_hyp_va() in VHE-specific parts of the hypervisor Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 08/17] KVM: arm64: Remove alternatives from sysreg accessors in VHE hypervisor context Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 09/17] KVM: arm64: Key use of VHE instructions in nVHE code off ARM64_KVM_HVHE Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 10/17] KVM: arm64: Force HCR_EL2.E2H when ARM64_KVM_HVHE is set Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 11/17] KVM: arm64: Disable TTBR1_EL2 when using ARM64_KVM_HVHE Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 12/17] KVM: arm64: Adjust EL2 stage-1 leaf AP bits when ARM64_KVM_HVHE is set Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 13/17] KVM: arm64: Rework CPTR_EL2 programming for HVHE configuration Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 14/17] KVM: arm64: Program the timer traps with VHE layout in hVHE mode Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 15/17] KVM: arm64: Force HCR_E2H in guest context when ARM64_KVM_HVHE is set Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 16/17] arm64: Allow arm64_sw.hvhe on command line Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07 ` [PATCH 17/17] KVM: arm64: Terrible timer hack for M1 with hVHE Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier
2022-10-20  9:07   ` Marc Zyngier

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