From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753122AbbIQFaM (ORCPT ); Thu, 17 Sep 2015 01:30:12 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:54508 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751709AbbIQFaK (ORCPT ); Thu, 17 Sep 2015 01:30:10 -0400 Date: Thu, 17 Sep 2015 07:30:04 +0200 From: Pavel Machek To: Chen Yu Cc: rjw@rjwysocki.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, bp@alien8.de, rui.zhang@intel.com, linux-pm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] [v4] x86, suspend: Save/restore extra MSR registers for suspend Message-ID: <20150917053004.GB6665@amd> References: <1440645507-17768-1-git-send-email-yu.c.chen@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1440645507-17768-1-git-send-email-yu.c.chen@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2015-08-27 11:18:27, Chen Yu wrote: > A bug is reported(https://bugzilla.redhat.com/show_bug.cgi?id=1227208) > that, after resumed from S3, CPU is running at a low speed. > After investigation, it is found that, BIOS has modified the value > of THERM_CONTROL register during S3, and changes it from 0 to 0x10, > since value of 0x10 means CPU can only get 25% of the Duty Cycle, > this triggers the problem. > > Here is a simple scenario to reproduce the issue: > 1.Boot up the system > 2.Get MSR with address 0x19a, it should be 0 > 3.Put the system into sleep, then wake it up > 4.Get MSR with address 0x19a, it should be 0(actually it shows 0x10) > > Although this is a BIOS issue, it would be more robust for linux to deal > with this situation. This patch fixes this issue by introducing a framework > to save/restore specified MSR registers(THERM_CONTROL in this case) > for suspend/resume. > > When user encounters a problematic platform and needs to protect the > MSRs during suspending, he can simply add a quirk entry in > msr_save_dmi_table, and customizes MSR registers inside the quirk > callback, for example: > > u32 msr_id_need_to_save[] = {MSR_ID0, MSR_ID1, MSR_ID2...}; > > and the quirk mechanism ensures that, once resumed from suspended, > the MSRs indicated by these IDs will be restored to their original values > before suspended. > > Since both 64/32-bit kernels are affected, this patch covers 64/32-bit > common code path. And because the MSRs specified by the user might not > be available or readable in any situation, we use rdmsrl_safe to safely > save these MSRs. > > Tested-by: Marcin Kaszewski > Signed-off-by: Chen Yu Acked-by: Pavel Machek -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html