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 <maz@kernel.org>

diff --git a/arch/arm64/include/asm/spectre.h b/arch/arm64/include/asm/spectre.h
index fcdfbce302bdfb9fec12cef198139b4814e9642d..52e788981f4a268d8b087e6825203b76d922f262 100644 (file)
--- 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 6f36c4f62f6945f1e74323b4987f4e2684445dcd..280b10762f6b77e15138019ac5c4d905ecd365cb 100644 (file)
--- 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");
+       }
 }