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From: Jeremy Linton <jeremy.linton@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: stefan.wahren@i2se.com, mlangsdo@redhat.com,
	suzuki.poulose@arm.com, marc.zyngier@arm.com,
	catalin.marinas@arm.com, julien.thierry@arm.com,
	will.deacon@arm.com, linux-kernel@vger.kernel.org,
	Jeremy Linton <jeremy.linton@arm.com>,
	steven.price@arm.com, ykaukab@suse.de, dave.martin@arm.com,
	shankerd@codeaurora.org
Subject: [PATCH v3 4/7] arm64: add sysfs vulnerability show for meltdown
Date: Wed,  9 Jan 2019 17:55:41 -0600
Message-ID: <20190109235544.2992426-5-jeremy.linton@arm.com> (raw)
In-Reply-To: <20190109235544.2992426-1-jeremy.linton@arm.com>

Display the mitigation status if active, otherwise
assume the cpu is safe unless it doesn't have CSV3
and isn't in our whitelist.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
---
 arch/arm64/kernel/cpufeature.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index ab784d7a0083..ef7bbc49ef78 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -944,8 +944,12 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
 	return has_cpuid_feature(entry, scope);
 }
 
+/* default value is invalid until unmap_kernel_at_el0() runs */
+static bool __meltdown_safe = true;
+
 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
 static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */
+extern uint arm64_requested_vuln_attrs;
 
 static bool is_cpu_meltdown_safe(void)
 {
@@ -972,6 +976,14 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 {
 	char const *str = "command line option";
 
+	bool meltdown_safe = is_cpu_meltdown_safe() ||
+		has_cpuid_feature(entry, scope);
+
+	if (!meltdown_safe)
+		__meltdown_safe = false;
+
+	arm64_requested_vuln_attrs |= VULN_MELTDOWN;
+
 	/*
 	 * For reasons that aren't entirely clear, enabling KPTI on Cavium
 	 * ThunderX leads to apparent I-cache corruption of kernel text, which
@@ -993,11 +1005,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
 		return true;
 
-	if (is_cpu_meltdown_safe())
-		return false;
-
-	/* Defer to CPU feature registers */
-	return !has_cpuid_feature(entry, scope);
+	return !meltdown_safe;
 }
 
 static void
@@ -2065,3 +2073,17 @@ static int __init enable_mrs_emulation(void)
 }
 
 core_initcall(enable_mrs_emulation);
+
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
+ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	if (arm64_kernel_unmapped_at_el0())
+		return sprintf(buf, "Mitigation: KPTI\n");
+
+	if (__meltdown_safe)
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Vulnerable\n");
+}
+#endif
-- 
2.17.2


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  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-09 23:55 [PATCH v3 0/7] arm64: add system vulnerability sysfs entries Jeremy Linton
2019-01-09 23:55 ` [PATCH v3 1/7] sysfs/cpu: Allow individual architectures to select vulnerabilities Jeremy Linton
2019-01-14 10:02   ` Suzuki K Poulose
2019-01-18 15:46     ` Greg KH
2019-01-18 16:31       ` Jeremy Linton
2019-01-09 23:55 ` [PATCH v3 2/7] arm64: add sysfs vulnerability show for spectre v1 Jeremy Linton
2019-01-09 23:55 ` [PATCH v3 3/7] arm64: kpti: move check for non-vulnerable CPUs to a function Jeremy Linton
2019-01-12 10:41   ` Stefan Wahren
2019-01-14 11:32   ` Suzuki K Poulose
2019-01-18 16:35     ` Jeremy Linton
2019-01-09 23:55 ` Jeremy Linton [this message]
2019-01-10  9:23   ` [PATCH v3 4/7] arm64: add sysfs vulnerability show for meltdown Julien Thierry
2019-01-10 14:10     ` Jeremy Linton
2019-01-10 14:16       ` Julien Thierry
2019-01-09 23:55 ` [PATCH v3 5/7] arm64: add sysfs vulnerability show for spectre v2 Jeremy Linton
2019-01-09 23:55 ` [PATCH v3 6/7] arm64: add sysfs vulnerability show for speculative store bypass Jeremy Linton
2019-01-14 10:15   ` Marc Zyngier
2019-01-14 16:37     ` Jeremy Linton
2019-01-14 17:05       ` Marc Zyngier
2019-01-09 23:55 ` [PATCH v3 7/7] arm64: enable generic CPU vulnerabilites support Jeremy Linton
2019-01-15 19:50 ` [PATCH v3 0/7] arm64: add system vulnerability sysfs entries Stefan Wahren
2019-01-15 21:21   ` Jeremy Linton
2019-01-18 18:05     ` Stefan Wahren
2019-01-18 22:22       ` Jeremy Linton
2019-01-19 11:52         ` Stefan Wahren

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