From 7f43c2014fa03bb8718569ae628acf2089683bff Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 26 Nov 2020 17:25:30 +0000 Subject: [PATCH] arm64: Make the Meltdown mitigation state available Our Meltdown mitigation state isn't exposed outside of cpufeature.c, contrary to the rest of the Spectre mitigation state. As we are going to use it in KVM, expose a arm64_get_meltdown_state() helper which returns the same possible values as arm64_get_spectre_v?_state(). Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/spectre.h | 2 ++ arch/arm64/kernel/cpufeature.c | 20 +++++++++++++++++--- 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/spectre.h b/arch/arm64/include/asm/spectre.h index fcdfbce..52e7889 100644 --- a/arch/arm64/include/asm/spectre.h +++ b/arch/arm64/include/asm/spectre.h @@ -29,4 +29,6 @@ bool has_spectre_v4(const struct arm64_cpu_capabilities *cap, int scope); void spectre_v4_enable_mitigation(const struct arm64_cpu_capabilities *__unused); void spectre_v4_enable_task_mitigation(struct task_struct *tsk); +enum mitigation_state arm64_get_meltdown_state(void); + #endif /* __ASM_SPECTRE_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6f36c4f..280b1076 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2846,14 +2846,28 @@ static int __init enable_mrs_emulation(void) core_initcall(enable_mrs_emulation); +enum mitigation_state arm64_get_meltdown_state(void) +{ + if (__meltdown_safe) + return SPECTRE_UNAFFECTED; + + if (arm64_kernel_unmapped_at_el0()) + return SPECTRE_MITIGATED; + + return SPECTRE_VULNERABLE; +} + ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) { - if (__meltdown_safe) + switch (arm64_get_meltdown_state()) { + case SPECTRE_UNAFFECTED: return sprintf(buf, "Not affected\n"); - if (arm64_kernel_unmapped_at_el0()) + case SPECTRE_MITIGATED: return sprintf(buf, "Mitigation: PTI\n"); - return sprintf(buf, "Vulnerable\n"); + default: + return sprintf(buf, "Vulnerable\n"); + } } -- 2.7.4