linux-kernel - Re: [PATCH 2/2] x86, microcode: Ensure that module is only loaded for

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Message-ID: <4F8BDB58.6070007@linux.vnet.ibm.com>
Date:	Mon, 16 Apr 2012 14:12:00 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	Borislav Petkov <borislav.petkov@....com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Kay Sievers <kay.sievers@...y.org>,
	Dave Jones <davej@...hat.com>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	tigran@...azian.fsnet.co.uk, hpa@...or.com, x86@...nel.org
Subject: Re: [PATCH 2/2] x86, microcode: Ensure that module is only loaded
 for

On 04/12/2012 10:04 PM, Borislav Petkov wrote:

> From: Andreas Herrmann <andreas.herrmann3@....com>
> Date: Thu, 12 Apr 2012 16:51:57 +0200
> Subject: [PATCH 2/2] x86, microcode: Ensure that module is only loaded for supported AMD CPUs
> 
> Exit early when there's no support for a particular CPU family. Also,
> fixup the "no support for this CPU vendor" to be issued only when the
> driver is attempted to be loaded on an unsupported vendor.
> 
> Cc: stable@...r.kernel.org
> Cc: Tigran Aivazian <tigran@...azian.fsnet.co.uk>
> Cc: Borislav Petkov <borislav.petkov@....com>
> [Boris: added a commit msg because Andreas is lazy]
> Signed-off-by: Andreas Herrmann <andreas.herrmann3@....com>
> ---


I guess a similar change in intel microcode driver would also be
worthwhile, right? If so, then the below patch might be useful:

----------------->

From: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: x86, microcode: Ensure that module is only loaded on supported Intel CPUs

Exit early when there's no support for a particular CPU family.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---

 arch/x86/kernel/microcode_intel.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/microcode_intel.c b/arch/x86/kernel/microcode_intel.c
index 3ca42d0..0327e2b 100644
--- a/arch/x86/kernel/microcode_intel.c
+++ b/arch/x86/kernel/microcode_intel.c
@@ -147,12 +147,6 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 
 	memset(csig, 0, sizeof(*csig));
 
-	if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6 ||
-	    cpu_has(c, X86_FEATURE_IA64)) {
-		pr_err("CPU%d not a capable Intel processor\n", cpu_num);
-		return -1;
-	}
-
 	csig->sig = cpuid_eax(0x00000001);
 
 	if ((c->x86_model >= 5) || (c->x86 > 6)) {
@@ -463,6 +457,14 @@ static struct microcode_ops microcode_intel_ops = {
 
 struct microcode_ops * __init init_intel_microcode(void)
 {
+	struct cpuinfo_x86 *c = &cpu_data(0);
+
+	if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6 ||
+	    cpu_has(c, X86_FEATURE_IA64)) {
+		pr_err("Intel CPU family 0x%x not supported\n", c->x86);
+		return NULL;
+	}
+
 	return &microcode_intel_ops;
 }
 


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