[PATCH v4.4 37/45] arm64: KVM: Report SMCCC_ARCH_WORKAROUND_1 BP hardening support
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: 2019-06-14 03:13:32
Also in:
stable
Subsystem:
arm port, arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), secure monitor call(smc) calling convention (smccc), the rest · Maintainers:
Russell King, Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Mark Rutland, Lorenzo Pieralisi, Sudeep Holla, Linus Torvalds
From: Mark Rutland <mark.rutland@arm.com> commit 6167ec5c9145cdf493722dfd80a5d48bafc4a18a upstream. A new feature of SMCCC 1.1 is that it offers firmware-based CPU workarounds. In particular, SMCCC_ARCH_WORKAROUND_1 provides BP hardening for CVE-2017-5715. If the host has some mitigation for this issue, report that we deal with it using SMCCC_ARCH_WORKAROUND_1, as we apply the host workaround on every guest exit. Tested-by: Ard Biesheuvel <redacted> Reviewed-by: Christoffer Dall <redacted> Signed-off-by: Marc Zyngier <redacted> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> [ v4.4: account for files moved to virt/ upstream ] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- arch/arm/include/asm/kvm_host.h | 6 ++++++ arch/arm/kvm/psci.c | 9 ++++++++- arch/arm64/include/asm/kvm_host.h | 5 +++++ include/linux/arm-smccc.h | 5 +++++ 4 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 6692982c9b57..2009894d9a8a 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h@@ -237,4 +237,10 @@ static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {} +static inline bool kvm_arm_harden_branch_predictor(void) +{ + /* No way to detect it yet, pretend it is not there. */ + return false; +} + #endif /* __ARM_KVM_HOST_H__ */
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index 9abf40734723..747319490268 100644
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c@@ -403,13 +403,20 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) { u32 func_id = smccc_get_function(vcpu); u32 val = PSCI_RET_NOT_SUPPORTED; + u32 feature; switch (func_id) { case ARM_SMCCC_VERSION_FUNC_ID: val = ARM_SMCCC_VERSION_1_1; break; case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: - /* Nothing supported yet */ + feature = smccc_get_arg1(vcpu); + switch(feature) { + case ARM_SMCCC_ARCH_WORKAROUND_1: + if (kvm_arm_harden_branch_predictor()) + val = 0; + break; + } break; default: return kvm_psci_call(vcpu);
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index a35ce7266aac..aca3a7e28777 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h@@ -258,4 +258,9 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); +static inline bool kvm_arm_harden_branch_predictor(void) +{ + return cpus_have_cap(ARM64_HARDEN_BRANCH_PREDICTOR); +} + #endif /* __ARM64_KVM_HOST_H__ */
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index da9f3916f9a9..1f02e4045a9e 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h@@ -73,6 +73,11 @@ ARM_SMCCC_SMC_32, \ 0, 1) +#define ARM_SMCCC_ARCH_WORKAROUND_1 \ + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ + ARM_SMCCC_SMC_32, \ + 0, 0x8000) + #ifndef __ASSEMBLY__ /**
--
2.21.0.rc0.269.g1a574e7a288b
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