linux-kernel - [PATCH] x86/cpu: clear X86_BUG_SPECTRE

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Date:   Wed, 15 Jan 2020 16:05:00 +0800
From:   Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To:     <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <hpa@...or.com>, <x86@...nel.org>, <linux-kernel@...r.kernel.org>
CC:     <DavidWang@...oxin.com>, <CooperYan@...oxin.com>,
        <QiyuanWang@...oxin.com>, <HerryYang@...oxin.com>
Subject: [PATCH] x86/cpu: clear X86_BUG_SPECTRE_V2 on Zhaoxin family 7 CPUs

These CPUs are not affected by spectre_v2, so clear spectre_v2 bug flag
in their specific initialization code.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
---
 arch/x86/kernel/cpu/centaur.c | 5 +++++
 arch/x86/kernel/cpu/zhaoxin.c | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c
index b98529e..3567560 100644
--- a/arch/x86/kernel/cpu/centaur.c
+++ b/arch/x86/kernel/cpu/centaur.c
@@ -250,6 +250,11 @@ static void init_centaur(struct cpuinfo_x86 *c)
 
 	if (cpu_has(c, X86_FEATURE_VMX))
 		centaur_detect_vmx_virtcap(c);
+
+	if (c->x86 == 7) {
+		setup_clear_cpu_cap(X86_BUG_SPECTRE_V2);
+		clear_bit(X86_BUG_SPECTRE_V2, (unsigned long *)cpu_caps_set);
+	}
 }
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/cpu/zhaoxin.c b/arch/x86/kernel/cpu/zhaoxin.c
index 452fd0a..ea7c52f 100644
--- a/arch/x86/kernel/cpu/zhaoxin.c
+++ b/arch/x86/kernel/cpu/zhaoxin.c
@@ -141,6 +141,11 @@ static void init_zhaoxin(struct cpuinfo_x86 *c)
 
 	if (cpu_has(c, X86_FEATURE_VMX))
 		zhaoxin_detect_vmx_virtcap(c);
+
+	if (c->x86 == 7) {
+		setup_clear_cpu_cap(X86_BUG_SPECTRE_V2);
+		clear_bit(X86_BUG_SPECTRE_V2, (unsigned long *)cpu_caps_set);
+	}
 }
 
 #ifdef CONFIG_X86_32
-- 
2.7.4