linux-kernel - [PATCH 3.16 042/410] x86/cpufeatures: Add AMD feature bits for Speculation Control

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Message-ID: <lsq.1528380321.870074724@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, arjan@...ux.intel.com,
        gnomes@...rguk.ukuu.org.uk, karahmed@...zon.de,
        "Tom Lendacky" <thomas.lendacky@....com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        torvalds@...ux-foundation.org, dave.hansen@...el.com,
        ak@...ux.intel.com, gregkh@...ux-foundation.org,
        ashok.raj@...el.com, "David Woodhouse" <dwmw@...zon.co.uk>,
        bp@...en8.de, peterz@...radead.org, pbonzini@...hat.com,
        tim.c.chen@...ux.intel.com,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Subject: [PATCH 3.16 042/410] x86/cpufeatures: Add AMD feature bits for
 Speculation Control

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

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

From: David Woodhouse <dwmw@...zon.co.uk>

commit 5d10cbc91d9eb5537998b65608441b592eec65e7 upstream.

AMD exposes the PRED_CMD/SPEC_CTRL MSRs slightly differently to Intel.
See http://lkml.kernel.org/r/2b3e25cc-286d-8bd0-aeaf-9ac4aae39de8@amd.com

Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: gnomes@...rguk.ukuu.org.uk
Cc: ak@...ux.intel.com
Cc: ashok.raj@...el.com
Cc: dave.hansen@...el.com
Cc: karahmed@...zon.de
Cc: arjan@...ux.intel.com
Cc: torvalds@...ux-foundation.org
Cc: peterz@...radead.org
Cc: bp@...en8.de
Cc: pbonzini@...hat.com
Cc: tim.c.chen@...ux.intel.com
Cc: gregkh@...ux-foundation.org
Link: https://lkml.kernel.org/r/1516896855-7642-4-git-send-email-dwmw@amazon.co.uk
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 3.16: This CPUID word wasn't used at all yet, so
 add it as feature word 11]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/include/asm/cpufeature.h | 7 ++++++-
 arch/x86/kernel/cpu/common.c      | 5 ++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -8,7 +8,7 @@
 #include <asm/required-features.h>
 #endif
 
-#define NCAPINTS	11	/* N 32-bit words worth of info */
+#define NCAPINTS	12	/* N 32-bit words worth of info */
 #define NBUGINTS	1	/* N 32-bit bug flags */
 
 /*
@@ -239,6 +239,11 @@
 #define X86_FEATURE_STIBP		(10*32+27) /* Single Thread Indirect Branch Predictors */
 #define X86_FEATURE_ARCH_CAPABILITIES	(10*32+29) /* IA32_ARCH_CAPABILITIES MSR (Intel) */
 
+/* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 11 */
+#define X86_FEATURE_AMD_PRED_CMD	(11*32+12) /* Prediction Command MSR (AMD) */
+#define X86_FEATURE_AMD_SPEC_CTRL	(11*32+14) /* Speculation Control MSR only (AMD) */
+#define X86_FEATURE_AMD_STIBP		(11*32+15) /* Single Thread Indirect Branch Predictors (AMD) */
+
 /*
  * BUG word(s)
  */
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -716,10 +716,13 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
 	}
 
 	if (c->extended_cpuid_level >= 0x80000008) {
-		u32 eax = cpuid_eax(0x80000008);
+		u32 eax, ebx, ecx, edx;
+
+		cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
 
 		c->x86_virt_bits = (eax >> 8) & 0xff;
 		c->x86_phys_bits = eax & 0xff;
+		c->x86_capability[11] = ebx;
 	}
 #ifdef CONFIG_X86_32
 	else if (cpu_has(c, X86_FEATURE_PAE) || cpu_has(c, X86_FEATURE_PSE36))