[PATCH 2/6] arm64: add sysfs vulnerability show for meltdown

[Mian Yousaf Kaukab]

Checking CSV3 support directly in case CONFIG_UNMAP_KERNEL_AT_EL0
is not enabled.

Signed-off-by: Mian Yousaf Kaukab <ykau...@suse.de>
---
 arch/arm64/kernel/cpu_errata.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index dec10898d688..996edb4e18ad 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -22,6 +22,7 @@
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 #include <asm/cpufeature.h>
+#include <asm/mmu.h>
 
 static bool __maybe_unused
 is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
@@ -683,3 +684,26 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
        {
        }
 };
+
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
+
+ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr,
+               char *buf)
+{
+       u64 pfr0;
+       u32 csv3;
+
+       if (arm64_kernel_unmapped_at_el0())
+               return sprintf(buf, "Mitigation: KPTI\n");
+
+       pfr0 = read_cpuid(ID_AA64PFR0_EL1);
+       csv3 = cpuid_feature_extract_unsigned_field(pfr0,
+                       ID_AA64PFR0_CSV3_SHIFT);
+
+       if (csv3 || is_cpu_meltdown_safe())
+               return sprintf(buf, "Not affected\n");
+
+       return sprintf(buf, "Vulnerable\n");
+}
+
+#endif
-- 
2.11.0