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From: <yee.lee@mediatek.com>
To: <linux-kernel@vger.kernel.org>
Cc: <nicholas.Tang@mediatek.com>, <Kuan-Ying.lee@mediatek.com>,
	<chinwen.chang@mediatek.com>, Yee Lee <yee.lee@mediatek.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Marc Zyngier <maz@kernel.org>,
	David Brazdil <dbrazdil@google.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ionela Voinescu <ionela.voinescu@arm.com>,
	Amit Daniel Kachhap <amit.kachhap@arm.com>,
	Quentin Perret <qperret@google.com>,
	Andrew Scull <ascull@google.com>,
	James Morse <james.morse@arm.com>, Fuad Tabba <tabba@google.com>,
	"moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
	<linux-arm-kernel@lists.infradead.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@lists.infradead.org>
Subject: [PATCH 1/1] arm64/cpufeature: Add option to disable mte support
Date: Wed, 28 Jul 2021 17:42:58 +0800	[thread overview]
Message-ID: <20210728094302.9949-2-yee.lee@mediatek.com> (raw)
In-Reply-To: <20210728094302.9949-1-yee.lee@mediatek.com>

From: Yee Lee <yee.lee@mediatek.com>

Add a static key to exapnd the logic of system_supports_mte().
This function controls mte enablement in both EL1 and EL0.

The static key, "arm64_mte_support" is default true and can
be disabled via the early_param.

Signed-off-by: Yee Lee <yee.lee@mediatek.com>
---
 arch/arm64/include/asm/cpufeature.h |  4 +++-
 arch/arm64/kernel/cpufeature.c      | 13 +++++++++++++
 arch/arm64/kernel/image-vars.h      |  3 +++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 9bb9d11750d7..0e5c82f2e012 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -420,6 +420,7 @@ static __always_inline bool is_hyp_code(void)
 extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
 extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS];
 extern struct static_key_false arm64_const_caps_ready;
+extern struct static_key_true arm64_mte_support;
 
 /* ARM64 CAPS + alternative_cb */
 #define ARM64_NPATCHABLE (ARM64_NCAPS + 1)
@@ -756,7 +757,8 @@ static __always_inline bool system_uses_irq_prio_masking(void)
 static inline bool system_supports_mte(void)
 {
 	return IS_ENABLED(CONFIG_ARM64_MTE) &&
-		cpus_have_const_cap(ARM64_MTE);
+		cpus_have_const_cap(ARM64_MTE) &&
+		static_branch_likely(&arm64_mte_support);
 }
 
 static inline bool system_has_prio_mask_debugging(void)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 0ead8bfedf20..b1602ad3d7c0 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1840,9 +1840,22 @@ static void bti_enable(const struct arm64_cpu_capabilities *__unused)
 }
 #endif /* CONFIG_ARM64_BTI */
 
+DEFINE_STATIC_KEY_TRUE(arm64_mte_support);
+EXPORT_SYMBOL(arm64_mte_support);
 #ifdef CONFIG_ARM64_MTE
+static int __init disable_arm64_mte_support(char *str)
+{
+	static_branch_disable(&arm64_mte_support);
+	return 0;
+}
+early_param("arm64_mte_not_support", disable_arm64_mte_support);
+
 static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
 {
+	if(!system_supports_mte()){
+		pr_info("MTE is disabled since system does not support.\n");
+		return ;
+	}
 	/*
 	 * Clear the tags in the zero page. This needs to be done via the
 	 * linear map which has the Tagged attribute.
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index c96a9a0043bf..04cf30ec84e7 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -83,6 +83,9 @@ KVM_NVHE_ALIAS(__icache_flags);
 KVM_NVHE_ALIAS(arm64_const_caps_ready);
 KVM_NVHE_ALIAS(cpu_hwcap_keys);
 
+/* Static key which indicates if system supports mte */
+KVM_NVHE_ALIAS(arm64_mte_support);
+
 /* Static keys which are set if a vGIC trap should be handled in hyp. */
 KVM_NVHE_ALIAS(vgic_v2_cpuif_trap);
 KVM_NVHE_ALIAS(vgic_v3_cpuif_trap);
-- 
2.18.0


  reply	other threads:[~2021-07-28  9:45 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-28  9:42 [PATCH 0/1] arm64/cpufeature: Add an option for mte support yee.lee
2021-07-28  9:42 ` yee.lee [this message]
2021-07-28  9:59   ` [PATCH 1/1] arm64/cpufeature: Add option to disable " Suzuki K Poulose
2021-07-28 10:05     ` Marc Zyngier

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