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
next prev parent reply other threads:[~2023-06-01 7:02 UTC|newest]
Thread overview: 19+ 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 ` [PATCH 01/17] arm64: Turn kaslr_feature_override into a generic SW feature override Marc Zyngier
2022-10-20 9:07 ` [PATCH 02/17] arm64: Add KVM_HVHE capability and has_hvhe() predicate Marc Zyngier
2023-06-01 7:01 ` Oliver Upton [this message]
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 ` [PATCH 04/17] arm64: Prevent the use of is_kernel_in_hyp_mode() in hypervisor code 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 ` [PATCH 06/17] arm64: Use CPACR_EL1 format to set CPTR_EL2 when E2H is set 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 ` [PATCH 08/17] KVM: arm64: Remove alternatives from sysreg accessors in VHE hypervisor context 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 ` [PATCH 10/17] KVM: arm64: Force HCR_EL2.E2H when ARM64_KVM_HVHE is set 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 ` [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 ` [PATCH 13/17] KVM: arm64: Rework CPTR_EL2 programming for HVHE configuration 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 ` [PATCH 15/17] KVM: arm64: Force HCR_E2H in guest context when ARM64_KVM_HVHE is set 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 ` [PATCH 17/17] KVM: arm64: Terrible timer hack for M1 with hVHE Marc Zyngier
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