linux-kernel - [PATCH] x86/speculation/spectre_v2: Exclude Zhaoxin CPUs from SPECTRE

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Message-ID: <1579146434-2668-1-git-send-email-TonyWWang-oc@zhaoxin.com>
Date:   Thu, 16 Jan 2020 11:47:14 +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>, <luto@...nel.org>,
        <pawan.kumar.gupta@...ux.intel.com>, <peterz@...radead.org>,
        <fenghua.yu@...el.com>, <vineela.tummalapalli@...el.com>,
        <linux-kernel@...r.kernel.org>
CC:     <DavidWang@...oxin.com>, <CooperYan@...oxin.com>,
        <QiyuanWang@...oxin.com>, <HerryYang@...oxin.com>
Subject: [PATCH] x86/speculation/spectre_v2: Exclude Zhaoxin CPUs from SPECTRE_V2

New Zhaoxin family 7 CPUs are not affected by SPECTRE_V2. So create
a separate cpu_vuln_whitelist flag bit NO_SPECTRE_V2 and add these
CPUs to the cpu vulnerability whitelist.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
---
 arch/x86/kernel/cpu/common.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 2e4d902..6048bd3 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1023,6 +1023,7 @@ static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
 #define MSBDS_ONLY		BIT(5)
 #define NO_SWAPGS		BIT(6)
 #define NO_ITLB_MULTIHIT	BIT(7)
+#define NO_SPECTRE_V2		BIT(8)
 
 #define VULNWL(_vendor, _family, _model, _whitelist)	\
 	{ X86_VENDOR_##_vendor, _family, _model, X86_FEATURE_ANY, _whitelist }
@@ -1084,6 +1085,10 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
 	/* FAMILY_ANY must be last, otherwise 0x0f - 0x12 matches won't work */
 	VULNWL_AMD(X86_FAMILY_ANY,	NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT),
 	VULNWL_HYGON(X86_FAMILY_ANY,	NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT),
+
+	/* Zhaoxin Family 7 */
+	VULNWL(CENTAUR,	7, X86_MODEL_ANY,	NO_SPECTRE_V2),
+	VULNWL(ZHAOXIN,	7, X86_MODEL_ANY,	NO_SPECTRE_V2),
 	{}
 };
 
@@ -1116,7 +1121,9 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 		return;
 
 	setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
-	setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+
+	if (!cpu_matches(NO_SPECTRE_V2))
+		setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
 
 	if (!cpu_matches(NO_SSB) && !(ia32_cap & ARCH_CAP_SSB_NO) &&
 	   !cpu_has(c, X86_FEATURE_AMD_SSB_NO))
-- 
2.7.4