Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755476Ab3GOU7C (ORCPT ); Mon, 15 Jul 2013 16:59:02 -0400 Received: from terminus.zytor.com ([198.137.202.10]:44759 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754697Ab3GOU7A (ORCPT ); Mon, 15 Jul 2013 16:59:00 -0400 Date: Mon, 15 Jul 2013 13:58:18 -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: 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 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]); Mon, 15 Jul 2013 13:58:26 -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: 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 Gitweb: http://git.kernel.org/tip/5ff560fd48d5b3d82fa0c3aff625c9da1a301911 Author: H. Peter Anvin AuthorDate: Fri, 12 Jul 2013 16:48:12 -0700 Committer: H. Peter Anvin CommitDate: Mon, 15 Jul 2013 13:50:54 -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/