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arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests

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Recent commits added the explicit notion of "workaround not required" to
the state of the Spectre v2 (aka. BP_HARDENING) workaround, where we
just had "needed" and "unknown" before.

Export this knowledge to the rest of the kernel and enhance the existing
kvm_arm_harden_branch_predictor() to report this new state as well.
Export this new state to guests when they use KVM's firmware interface
emulation.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Andre Przywara
2019-05-03 15:27:48 +01:00
committed by Marc Zyngier
parent 80f393a23b
commit c118bbb527
5 changed files with 56 additions and 11 deletions
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12
arch/arm/include/asm/kvm_host.h
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@@ -362,7 +362,11 @@ static inline void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) {}
static inline void kvm_arm_vhe_guest_enter(void) {}
static inline void kvm_arm_vhe_guest_exit(void) {}
static inline bool kvm_arm_harden_branch_predictor(void)
#define KVM_BP_HARDEN_UNKNOWN -1
#define KVM_BP_HARDEN_WA_NEEDED 0
#define KVM_BP_HARDEN_NOT_REQUIRED 1
static inline int kvm_arm_harden_branch_predictor(void)
{
switch(read_cpuid_part()) {
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
@@ -370,10 +374,12 @@ static inline bool kvm_arm_harden_branch_predictor(void)
case ARM_CPU_PART_CORTEX_A12:
case ARM_CPU_PART_CORTEX_A15:
case ARM_CPU_PART_CORTEX_A17:
return true;
return KVM_BP_HARDEN_WA_NEEDED;
#endif
case ARM_CPU_PART_CORTEX_A7:
return KVM_BP_HARDEN_NOT_REQUIRED;
default:
return false;
return KVM_BP_HARDEN_UNKNOWN;
}
}