On Thu, Aug 11, 2022 at 05:02:20PM +0000, Oliver Upton wrote:
> KVM does not support AArch32 on asymmetric systems. To that end, enforce
> AArch64-only behavior on PMCR_EL1.LC when on an asymmetric system.
>
> Fixes: 2122a833316f ("arm64: Allow mismatched 32-bit EL0 support")
> Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 4 ++++
> arch/arm64/kvm/arm.c | 3 +--
> arch/arm64/kvm/sys_regs.c | 4 ++--
> 3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index f38ef299f13b..e9c9388ccc02 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -929,6 +929,10 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
> (system_supports_mte() && \
> test_bit(KVM_ARCH_FLAG_MTE_ENABLED, &(kvm)->arch.flags))
>
> +#define kvm_supports_32bit_el0() \
> + (system_supports_32bit_el0() && \
> + !static_branch_unlikely(&arm64_mismatched_32bit_el0))
> +
> int kvm_trng_call(struct kvm_vcpu *vcpu);
> #ifdef CONFIG_KVM
> extern phys_addr_t hyp_mem_base;
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 986cee6fbc7f..bef3849c564f 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -757,8 +757,7 @@ static bool vcpu_mode_is_bad_32bit(struct kvm_vcpu *vcpu)
> if (likely(!vcpu_mode_is_32bit(vcpu)))
> return false;
>
> - return !system_supports_32bit_el0() ||
> - static_branch_unlikely(&arm64_mismatched_32bit_el0);
> + return kvm_supports_32bit_el0();
Lol, promised this was lightly tested :) Read the patch once more, this
will need to be:
return !kvm_supports_32bit_el0();
I'll fix it in v2 but will wait a bit for folks to review.
--
Thanks,
Oliver
> }
>
> /**
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index c059b259aea6..3234f50b8c4b 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -652,7 +652,7 @@ static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> */
> val = ((pmcr & ~ARMV8_PMU_PMCR_MASK)
> | (ARMV8_PMU_PMCR_MASK & 0xdecafbad)) & (~ARMV8_PMU_PMCR_E);
> - if (!system_supports_32bit_el0())
> + if (!kvm_supports_32bit_el0())
> val |= ARMV8_PMU_PMCR_LC;
> __vcpu_sys_reg(vcpu, r->reg) = val;
> }
> @@ -701,7 +701,7 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
> val = __vcpu_sys_reg(vcpu, PMCR_EL0);
> val &= ~ARMV8_PMU_PMCR_MASK;
> val |= p->regval & ARMV8_PMU_PMCR_MASK;
> - if (!system_supports_32bit_el0())
> + if (!kvm_supports_32bit_el0())
> val |= ARMV8_PMU_PMCR_LC;
> __vcpu_sys_reg(vcpu, PMCR_EL0) = val;
> kvm_pmu_handle_pmcr(vcpu, val);
> --
> 2.37.1.559.g78731f0fdb-goog
>
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