From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756632Ab1KOP4S (ORCPT ); Tue, 15 Nov 2011 10:56:18 -0500 Received: from s15228384.onlinehome-server.info ([87.106.30.177]:47174 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756463Ab1KOP4R (ORCPT ); Tue, 15 Nov 2011 10:56:17 -0500 From: Borislav Petkov To: "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner Cc: LKML , Daniel Drake , Borislav Petkov Subject: [PATCH] x86, microcode, AMD: Restrict microcode reporting Date: Tue, 15 Nov 2011 16:55:56 +0100 Message-Id: <1321372556-6205-1-git-send-email-bp@amd64.org> X-Mailer: git-send-email 1.7.8.rc0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Borislav Petkov bcb80e53877c ("x86, microcode, AMD: Add microcode revision to /proc/cpuinfo") added support for dumping microcode patch level in /proc/cpuinfo on AMD. Although we were very cautious and did rdmsr_safe the microcode patch level MSR, this broke booting on Geode LX because this CPU doesn't have that MSR and at the time we do the read, exception tables which are used by rdmsr_safe are not yet initialized, leading to the boot hang. This is the simple fix which enables the microcode line in /proc/cpuinfo for K8 and newer (it is not that interesting for older boxes anyway :-)). Reported-and-bisected-and-tested-by: Daniel Drake Link: http://lkml.kernel.org/r/CAMLZHHTSuHZoPbm_YfB8G05JA+xKCE4+Jmj4NW8mnZUHogQSBA@mail.gmail.com Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/amd.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index c7e46cb..a72d183 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -474,7 +474,8 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) } #endif - rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); + if (c->x86 >= 0xf) + rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); } static void __cpuinit init_amd(struct cpuinfo_x86 *c) -- 1.7.8.rc0