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Subject[PATCH 4.9 65/66] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit 5d81f7dc9bca4f4963092433e27b508cbe524a32 upstream.

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>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/include/asm/kvm_host.h | 12 ++++++++++++
arch/arm/kvm/psci.c | 18 ++++++++++++++++--
arch/arm64/include/asm/kvm_host.h | 23 +++++++++++++++++++++++
arch/arm64/kvm/reset.c | 4 ++++
4 files changed, 55 insertions(+), 2 deletions(-)

--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -327,4 +327,16 @@ static inline bool kvm_arm_harden_branch
return false;
}

+#define KVM_SSBD_UNKNOWN -1
+#define KVM_SSBD_FORCE_DISABLE 0
+#define KVM_SSBD_KERNEL 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;
+}
+
#endif /* __ARM_KVM_HOST_H__ */
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -403,7 +403,7 @@ static int kvm_psci_call(struct kvm_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) {
@@ -415,7 +415,21 @@ int kvm_hvc_call_handler(struct kvm_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_KERNEL:
+ val = SMCCC_RET_SUCCESS;
+ break;
+ case KVM_SSBD_FORCE_ENABLE:
+ case KVM_SSBD_MITIGATED:
+ val = SMCCC_RET_NOT_REQUIRED;
+ break;
+ }
break;
}
break;
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -425,4 +425,27 @@ static inline bool kvm_arm_harden_branch
return cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR);
}

+#define KVM_SSBD_UNKNOWN -1
+#define KVM_SSBD_FORCE_DISABLE 0
+#define KVM_SSBD_KERNEL 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_KERNEL:
+ return KVM_SSBD_KERNEL;
+ 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;
+ }
+}
+
#endif /* __ARM64_KVM_HOST_H__ */
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -135,6 +135,10 @@ 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_KERNEL)
+ vcpu->arch.workaround_flags |= VCPU_WORKAROUND_2_FLAG;
+
/* Reset timer */
return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
}

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