BugLink: http://bugs.launchpad.net/bugs/1751064
Commit
6167ec5c9145 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 <ard.biesheuvel@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Conflicts:
arch/arm/include/asm/kvm_host.h
arch/arm64/include/asm/kvm_host.h
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
/* All host FP/SIMD state is restored on guest exit, so nothing to save: */
static inline void kvm_fpsimd_flush_cpu_state(void) {}
/* All host FP/SIMD state is restored on guest exit, so nothing to save: */
static inline void kvm_fpsimd_flush_cpu_state(void) {}
+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__ */
#endif /* __ARM_KVM_HOST_H__ */
+static inline bool kvm_arm_harden_branch_predictor(void)
+{
+ return cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR);
+}
+
#endif /* __ARM64_KVM_HOST_H__ */
#endif /* __ARM64_KVM_HOST_H__ */
ARM_SMCCC_SMC_32, \
0, 1)
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__
#include <linux/linkage.h>
#ifndef __ASSEMBLY__
#include <linux/linkage.h>
{
u32 func_id = smccc_get_function(vcpu);
u32 val = PSCI_RET_NOT_SUPPORTED;
{
u32 func_id = smccc_get_function(vcpu);
u32 val = PSCI_RET_NOT_SUPPORTED;
switch (func_id) {
case ARM_SMCCC_VERSION_FUNC_ID:
val = ARM_SMCCC_VERSION_1_1;
break;
case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
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);
break;
default:
return kvm_psci_call(vcpu);