From c118bbb52743df70e6297671606c1c08edc659fe Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Fri, 3 May 2019 15:27:48 +0100 Subject: arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests 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 Reviewed-by: Steven Price Signed-off-by: Marc Zyngier --- arch/arm64/kernel/cpu_errata.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'arch/arm64/kernel') diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index ca11ff7bf55e..1e43ba5c79b7 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -554,6 +554,17 @@ cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused) static bool __hardenbp_enab = true; static bool __spectrev2_safe = true; +int get_spectre_v2_workaround_state(void) +{ + if (__spectrev2_safe) + return ARM64_BP_HARDEN_NOT_REQUIRED; + + if (!__hardenbp_enab) + return ARM64_BP_HARDEN_UNKNOWN; + + return ARM64_BP_HARDEN_WA_NEEDED; +} + /* * List of CPUs that do not need any Spectre-v2 mitigation at all. */ @@ -854,13 +865,15 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf) { - if (__spectrev2_safe) + switch (get_spectre_v2_workaround_state()) { + case ARM64_BP_HARDEN_NOT_REQUIRED: return sprintf(buf, "Not affected\n"); - - if (__hardenbp_enab) + case ARM64_BP_HARDEN_WA_NEEDED: return sprintf(buf, "Mitigation: Branch predictor hardening\n"); - - return sprintf(buf, "Vulnerable\n"); + case ARM64_BP_HARDEN_UNKNOWN: + default: + return sprintf(buf, "Vulnerable\n"); + } } ssize_t cpu_show_spec_store_bypass(struct device *dev, -- cgit v1.2.3