linux-kernel - [tip:x86/cpu] x86, AMD: Correct {rd,wr}msr_amd

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Message-ID: <tip-682469a5db6fade318a72406935b5000186e5643@git.kernel.org>
Date:	Tue, 16 Apr 2013 06:53:09 -0700
From:	tip-bot for Borislav Petkov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	tglx@...utronix.de, bp@...e.de
Subject: [tip:x86/cpu] x86, AMD: Correct {rd,wr}msr_amd_safe warnings

Commit-ID:  682469a5db6fade318a72406935b5000186e5643
Gitweb:     http://git.kernel.org/tip/682469a5db6fade318a72406935b5000186e5643
Author:     Borislav Petkov <bp@...e.de>
AuthorDate: Mon, 8 Apr 2013 17:57:45 +0200
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Tue, 16 Apr 2013 11:50:51 +0200

x86, AMD: Correct {rd,wr}msr_amd_safe warnings

The idea with those routines is to slowly phase them out and not call
them on anything else besides K8. They even have a check for that which,
when called too early, fails. Let me explain:

It gets the cpuinfo_x86 pointer from the per_cpu array and when this
happens for cpu0, before its boot_cpu_data has been copied back to the
per_cpu array in smp_store_boot_cpu_info(), we get an empty struct and
thus the check fails.

Use boot_cpu_data directly instead.

Signed-off-by: Borislav Petkov <bp@...e.de>
Link: http://lkml.kernel.org/r/1365436666-9837-4-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@...or.com>
---
 arch/x86/kernel/cpu/amd.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 9a2a716..cea02d7 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -20,11 +20,11 @@
 
 static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
 {
-	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
 	u32 gprs[8] = { 0 };
 	int err;
 
-	WARN_ONCE((c->x86 != 0xf), "%s should only be used on K8!\n", __func__);
+	WARN_ONCE((boot_cpu_data.x86 != 0xf),
+		  "%s should only be used on K8!\n", __func__);
 
 	gprs[1] = msr;
 	gprs[7] = 0x9c5a203a;
@@ -38,10 +38,10 @@ static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
 
 static inline int wrmsrl_amd_safe(unsigned msr, unsigned long long val)
 {
-	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
 	u32 gprs[8] = { 0 };
 
-	WARN_ONCE((c->x86 != 0xf), "%s should only be used on K8!\n", __func__);
+	WARN_ONCE((boot_cpu_data.x86 != 0xf),
+		  "%s should only be used on K8!\n", __func__);
 
 	gprs[0] = (u32)val;
 	gprs[1] = msr;
--
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