Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758128Ab3GMDWT (ORCPT ); Fri, 12 Jul 2013 23:22:19 -0400 Received: from terminus.zytor.com ([198.137.202.10]:43960 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757969Ab3GMDWR (ORCPT ); Fri, 12 Jul 2013 23:22:17 -0400 Date: Fri, 12 Jul 2013 20:21:48 -0700 From: "tip-bot for H. Peter Anvin" Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, onny@project-insanity.org, tglx@linutronix.de, hpa@linux.intel.com, rjw@sisk.pl, christian.suenkenberg@student.kit.edu Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, onny@project-insanity.org, tglx@linutronix.de, hpa@linux.intel.com, rjw@sisk.pl, christian.suenkenberg@student.kit.edu In-Reply-To: <51DDC972.3010005@student.kit.edu> References: <51DDC972.3010005@student.kit.edu> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86, suspend: Handle CPUs which fail to #GP on RDMSR Git-Commit-ID: 3a783f6e39cc6c89da8846312f29ca47affaa470 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Fri, 12 Jul 2013 20:21:56 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2939 Lines: 73 Commit-ID: 3a783f6e39cc6c89da8846312f29ca47affaa470 Gitweb: http://git.kernel.org/tip/3a783f6e39cc6c89da8846312f29ca47affaa470 Author: H. Peter Anvin AuthorDate: Fri, 12 Jul 2013 16:48:12 -0700 Committer: H. Peter Anvin CommitDate: Fri, 12 Jul 2013 16:48:12 -0700 x86, suspend: Handle CPUs which fail to #GP on RDMSR There are CPUs which have errata causing RDMSR of a nonexistent MSR to not fault. We would then try to WRMSR to restore the value of that MSR, causing a crash. Specifically, some Pentium M variants would have this problem trying to save and restore the non-existent EFER, causing a crash on resume. Work around this by making sure we can write back the result at suspend time. Huge thanks to Christian Sünkenberg for finding the offending erratum that finally deciphered the mystery. Reported-and-tested-by: Johan Heinrich Debugged-by: Christian Sünkenberg Acked-by: Rafael J. Wysocki Link: http://lkml.kernel.org/r/51DDC972.3010005@student.kit.edu Cc: # v3.7+ --- arch/x86/kernel/acpi/sleep.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index 2a34aaf..3312010 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -48,9 +48,20 @@ int x86_acpi_suspend_lowlevel(void) #ifndef CONFIG_64BIT native_store_gdt((struct desc_ptr *)&header->pmode_gdt); + /* + * We have to check that we can write back the value, and not + * just read it. At least on 90 nm Pentium M (Family 6, Model + * 13), reading an invalid MSR is not guaranteed to trap, see + * Erratum X4 in "Intel Pentium M Processor on 90 nm Process + * with 2-MB L2 Cache and Intel® Processor A100 and A110 on 90 + * nm process with 512-KB L2 Cache Specification Update". + */ if (!rdmsr_safe(MSR_EFER, &header->pmode_efer_low, - &header->pmode_efer_high)) + &header->pmode_efer_high) && + !wrmsr_safe(MSR_EFER, + header->pmode_efer_low, + header->pmode_efer_high)) header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_EFER); #endif /* !CONFIG_64BIT */ @@ -61,7 +72,10 @@ int x86_acpi_suspend_lowlevel(void) } if (!rdmsr_safe(MSR_IA32_MISC_ENABLE, &header->pmode_misc_en_low, - &header->pmode_misc_en_high)) + &header->pmode_misc_en_high) && + !wrmsr_safe(MSR_IA32_MISC_ENABLE, + header->pmode_misc_en_low, + header->pmode_misc_en_high)) header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE); header->realmode_flags = acpi_realmode_flags; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/