linux-kernel - [PATCH 5.4 27/34] x86/speculation/spectre_v2: Exclude Zhaoxin CPUs from SPECTRE

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Message-Id: <20200609174056.885099252@linuxfoundation.org>
Date:   Tue,  9 Jun 2020 19:45:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tony W Wang-oc <TonyWWang-oc@...oxin.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 5.4 27/34] x86/speculation/spectre_v2: Exclude Zhaoxin CPUs from SPECTRE_V2

From: Tony W Wang-oc <TonyWWang-oc@...oxin.com>

commit 1e41a766c98b481400ab8c5a7aa8ea63a1bb03de upstream.

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

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/1579227872-26972-2-git-send-email-TonyWWang-oc@zhaoxin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/cpu/common.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1024,6 +1024,7 @@ static void identify_cpu_without_cpuid(s
 #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 }
@@ -1085,6 +1086,10 @@ static const __initconst struct x86_cpu_
 	/* 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),
 	{}
 };
 
@@ -1117,7 +1122,9 @@ static void __init cpu_set_bug_bits(stru
 		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))