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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 3/7] arm64: kpti: move check for non-vulnerable CPUs to a function
Date: Wed,  9 Jan 2019 17:55:40 -0600
Message-ID: <20190109235544.2992426-4-jeremy.linton@arm.com> (raw)
In-Reply-To: <20190109235544.2992426-1-jeremy.linton@arm.com>

From: Mian Yousaf Kaukab <ykaukab@suse.de>

Add is_meltdown_safe() which is a whitelist of known safe cores.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
[Moved location of function]
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
---
 arch/arm64/kernel/cpufeature.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4f272399de89..ab784d7a0083 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -947,8 +947,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
 static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */
 
-static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
-				int scope)
+static bool is_cpu_meltdown_safe(void)
 {
 	/* List of CPUs that are not vulnerable and don't need KPTI */
 	static const struct midr_range kpti_safe_list[] = {
@@ -962,6 +961,15 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 		MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
 		{ /* sentinel */ }
 	};
+	if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
+		return true;
+
+	return false;
+}
+
+static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
+				int scope)
+{
 	char const *str = "command line option";
 
 	/*
@@ -985,8 +993,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
 		return true;
 
-	/* Don't force KPTI for CPUs that are not vulnerable */
-	if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
+	if (is_cpu_meltdown_safe())
 		return false;
 
 	/* Defer to CPU feature registers */
-- 
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 ` Jeremy Linton [this message]
2019-01-12 10:41   ` [PATCH v3 3/7] arm64: kpti: move check for non-vulnerable CPUs to a function Stefan Wahren
2019-01-14 11:32   ` Suzuki K Poulose
2019-01-18 16:35     ` Jeremy Linton
2019-01-09 23:55 ` [PATCH v3 4/7] arm64: add sysfs vulnerability show for meltdown Jeremy Linton
2019-01-10  9:23   ` 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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