linux-kernel - [PATCH 3.16 002/131] x86/bugs: Concentrate bug detection into a separate function

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Message-ID: <lsq.1538257387.192134744@decadent.org.uk>
Date:   Sat, 29 Sep 2018 22:43:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
        "Borislav Petkov" <bp@...e.de>, "Ingo Molnar" <mingo@...nel.org>,
        "Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.16 002/131] x86/bugs: Concentrate bug detection into a
 separate function

3.16.59-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

commit 4a28bfe3267b68e22c663ac26185aa16c9b879ef upstream.

Combine the various logic which goes through all those
x86_cpu_id matching structures in one function.

Suggested-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/cpu/common.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -803,21 +803,27 @@ static const __initconst struct x86_cpu_
 	{}
 };
 
-static bool __init cpu_vulnerable_to_meltdown(struct cpuinfo_x86 *c)
+static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 {
 	u64 ia32_cap = 0;
 
+	if (x86_match_cpu(cpu_no_speculation))
+		return;
+
+	setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
+	setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+
 	if (x86_match_cpu(cpu_no_meltdown))
-		return false;
+		return;
 
 	if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
 		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
 
 	/* Rogue Data Cache Load? No! */
 	if (ia32_cap & ARCH_CAP_RDCL_NO)
-		return false;
+		return;
 
-	return true;
+	setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
 }
 
 /*
@@ -868,12 +874,7 @@ static void __init early_identify_cpu(st
 
 	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
 
-	if (!x86_match_cpu(cpu_no_speculation)) {
-		if (cpu_vulnerable_to_meltdown(c))
-			setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
-		setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
-		setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
-	}
+	cpu_set_bug_bits(c);
 }
 
 void __init early_cpu_init(void)