From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932310AbeDZOKE (ORCPT ); Thu, 26 Apr 2018 10:10:04 -0400 Received: from terminus.zytor.com ([198.137.202.136]:34077 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932288AbeDZOKA (ORCPT ); Thu, 26 Apr 2018 10:10:00 -0400 Date: Thu, 26 Apr 2018 07:09:46 -0700 From: tip-bot for Yazen Ghannam Message-ID: Cc: bp@suse.de, linux-kernel@vger.kernel.org, tglx@linutronix.de, yazen.ghannam@amd.com, mingo@kernel.org, Yazen.Ghannam@amd.com, hpa@zytor.com Reply-To: Yazen.Ghannam@amd.com, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, yazen.ghannam@amd.com, bp@suse.de, linux-kernel@vger.kernel.org In-Reply-To: <20180403140228.58540-1-Yazen.Ghannam@amd.com> References: <20180403140228.58540-1-Yazen.Ghannam@amd.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/smpboot: Don't use mwait_play_dead() on AMD systems Git-Commit-ID: da6fa7ef67f07108a1b0cb9fd9e7fcaabd39c051 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: da6fa7ef67f07108a1b0cb9fd9e7fcaabd39c051 Gitweb: https://git.kernel.org/tip/da6fa7ef67f07108a1b0cb9fd9e7fcaabd39c051 Author: Yazen Ghannam AuthorDate: Tue, 3 Apr 2018 09:02:28 -0500 Committer: Thomas Gleixner CommitDate: Thu, 26 Apr 2018 16:06:19 +0200 x86/smpboot: Don't use mwait_play_dead() on AMD systems Recent AMD systems support using MWAIT for C1 state. However, MWAIT will not allow deeper cstates than C1 on current systems. play_dead() expects to use the deepest state available. The deepest state available on AMD systems is reached through SystemIO or HALT. If MWAIT is available, it is preferred over the other methods, so the CPU never reaches the deepest possible state. Don't try to use MWAIT to play_dead() on AMD systems. Instead, use CPUIDLE to enter the deepest state advertised by firmware. If CPUIDLE is not available then fallback to HALT. Signed-off-by: Yazen Ghannam Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: stable@vger.kernel.org Cc: Yazen Ghannam Link: https://lkml.kernel.org/r/20180403140228.58540-1-Yazen.Ghannam@amd.com --- arch/x86/kernel/smpboot.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 45175b81dd5b..0f1cbb042f49 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1571,6 +1571,8 @@ static inline void mwait_play_dead(void) void *mwait_ptr; int i; + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) + return; if (!this_cpu_has(X86_FEATURE_MWAIT)) return; if (!this_cpu_has(X86_FEATURE_CLFLUSH))