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SubjectRe: [PATCH 14/14] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID
On Tue, May 22, 2018 at 04:06:48PM +0100, Marc Zyngier wrote:
> Now that all our infrastructure is in place, let's expose the
> availability of ARCH_WORKAROUND_2 to guests. We take this opportunity
> to tidy up a couple of SMCCC constants.
>
> Acked-by: Christoffer Dall <christoffer.dall@arm.com>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Reviewed-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
> arch/arm/include/asm/kvm_host.h | 12 ++++++++++++
> arch/arm64/include/asm/kvm_host.h | 23 +++++++++++++++++++++++
> arch/arm64/kvm/reset.c | 4 ++++
> virt/kvm/arm/psci.c | 18 ++++++++++++++++--
> 4 files changed, 55 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index c7c28c885a19..d478766b56c1 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -315,6 +315,18 @@ static inline bool kvm_arm_harden_branch_predictor(void)
> return false;
> }
>
> +#define KVM_SSBD_UNKNOWN -1
> +#define KVM_SSBD_FORCE_DISABLE 0
> +#define KVM_SSBD_EL1_ENTRY 1
> +#define KVM_SSBD_FORCE_ENABLE 2
> +#define KVM_SSBD_MITIGATED 3
> +
> +static inline int kvm_arm_have_ssbd(void)
> +{
> + /* No way to detect it yet, pretend it is not there. */
> + return KVM_SSBD_UNKNOWN;
> +}
> +
> static inline void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu) {}
> static inline void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu) {}
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 9bef3f69bdcd..082b0dbb85c6 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -455,6 +455,29 @@ static inline bool kvm_arm_harden_branch_predictor(void)
> return cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR);
> }
>
> +#define KVM_SSBD_UNKNOWN -1
> +#define KVM_SSBD_FORCE_DISABLE 0
> +#define KVM_SSBD_EL1_ENTRY 1
> +#define KVM_SSBD_FORCE_ENABLE 2
> +#define KVM_SSBD_MITIGATED 3
> +
> +static inline int kvm_arm_have_ssbd(void)
> +{
> + switch (arm64_get_ssbd_state()) {
> + case ARM64_SSBD_FORCE_DISABLE:
> + return KVM_SSBD_FORCE_DISABLE;
> + case ARM64_SSBD_EL1_ENTRY:
> + return KVM_SSBD_EL1_ENTRY;
> + case ARM64_SSBD_FORCE_ENABLE:
> + return KVM_SSBD_FORCE_ENABLE;
> + case ARM64_SSBD_MITIGATED:
> + return KVM_SSBD_MITIGATED;
> + case ARM64_SSBD_UNKNOWN:
> + default:
> + return KVM_SSBD_UNKNOWN;
> + }
> +}
> +
> void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu);
> void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu);
>
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index 3256b9228e75..20a7dfee8494 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -122,6 +122,10 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
> /* Reset PMU */
> kvm_pmu_vcpu_reset(vcpu);
>
> + /* Default workaround setup is enabled (if supported) */
> + if (kvm_arm_have_ssbd() == KVM_SSBD_EL1_ENTRY)
> + vcpu->arch.workaround_flags |= VCPU_WORKAROUND_2_FLAG;
> +
> /* Reset timer */
> return kvm_timer_vcpu_reset(vcpu);
> }
> diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
> index c4762bef13c6..4843bfa1f986 100644
> --- a/virt/kvm/arm/psci.c
> +++ b/virt/kvm/arm/psci.c
> @@ -405,7 +405,7 @@ static int kvm_psci_call(struct kvm_vcpu *vcpu)
> int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
> {
> u32 func_id = smccc_get_function(vcpu);
> - u32 val = PSCI_RET_NOT_SUPPORTED;
> + u32 val = SMCCC_RET_NOT_SUPPORTED;
> u32 feature;
>
> switch (func_id) {
> @@ -417,7 +417,21 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
> switch(feature) {
> case ARM_SMCCC_ARCH_WORKAROUND_1:
> if (kvm_arm_harden_branch_predictor())
> - val = 0;
> + val = SMCCC_RET_SUCCESS;
> + break;
> + case ARM_SMCCC_ARCH_WORKAROUND_2:
> + switch (kvm_arm_have_ssbd()) {
> + case KVM_SSBD_FORCE_DISABLE:
> + case KVM_SSBD_UNKNOWN:
> + break;
> + case KVM_SSBD_EL1_ENTRY:
> + val = SMCCC_RET_SUCCESS;
> + break;
> + case KVM_SSBD_FORCE_ENABLE:
> + case KVM_SSBD_MITIGATED:
> + val = SMCCC_RET_NOT_REQUIRED;
> + break;
> + }
> break;
> }
> break;
> --
> 2.14.2
>

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