From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3A77C4321D for ; Thu, 23 Aug 2018 08:32:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 614912147A for ; Thu, 23 Aug 2018 08:32:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 614912147A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731788AbeHWMBa (ORCPT ); Thu, 23 Aug 2018 08:01:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48242 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729390AbeHWMB3 (ORCPT ); Thu, 23 Aug 2018 08:01:29 -0400 Received: from localhost (5355525A.cm-6-6b.dynamic.ziggo.nl [83.85.82.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id B82F48B1; Thu, 23 Aug 2018 08:32:55 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Zijlstra , Peng Hao , Paolo Bonzini , Sasha Levin Subject: [PATCH 4.14 191/217] kvmclock: fix TSC calibration for nested guests Date: Thu, 23 Aug 2018 09:55:04 +0200 Message-Id: <20180823075514.241182583@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180823075505.090246914@linuxfoundation.org> References: <20180823075505.090246914@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peng Hao [ Upstream commit e10f7805032365cc11c739a97f226ebb48aee042 ] Inside a nested guest, access to hardware can be slow enough that tsc_read_refs always return ULLONG_MAX, causing tsc_refine_calibration_work to be called periodically and the nested guest to spend a lot of time reading the ACPI timer. However, if the TSC frequency is available from the pvclock page, we can just set X86_FEATURE_TSC_KNOWN_FREQ and avoid the recalibration. 'refine' operation. Suggested-by: Peter Zijlstra Signed-off-by: Peng Hao [Commit message rewritten. - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/kvmclock.c | 1 + 1 file changed, 1 insertion(+) --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -143,6 +143,7 @@ static unsigned long kvm_get_tsc_khz(voi src = &hv_clock[cpu].pvti; tsc_khz = pvclock_tsc_khz(src); put_cpu(); + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); return tsc_khz; }