From patchwork Tue Jun 15 07:34:07 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zachary Amsden X-Patchwork-Id: 106157 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.3/8.14.3) with ESMTP id o5F7cinf009615 for ; Tue, 15 Jun 2010 07:38:46 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754973Ab0FOHhm (ORCPT ); Tue, 15 Jun 2010 03:37:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39955 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754729Ab0FOHef (ORCPT ); Tue, 15 Jun 2010 03:34:35 -0400 Received: from int-mx04.intmail.prod.int.phx2.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.17]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o5F7YZsC028344 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 15 Jun 2010 03:34:35 -0400 Received: from mysore (vpn-8-141.rdu.redhat.com [10.11.8.141]) by int-mx04.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o5F7YL2f024602; Tue, 15 Jun 2010 03:34:33 -0400 From: Zachary Amsden To: avi@redhat.com, mtosatti@redhat.com, glommer@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Zachary Amsden Subject: [PATCH 05/17] Keep SMP VMs more in sync on unstable TSC Date: Mon, 14 Jun 2010 21:34:07 -1000 Message-Id: <1276587259-32319-6-git-send-email-zamsden@redhat.com> In-Reply-To: <1276587259-32319-1-git-send-email-zamsden@redhat.com> References: <1276587259-32319-1-git-send-email-zamsden@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.17 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Tue, 15 Jun 2010 07:38:46 +0000 (UTC) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 94f6ce8..1afecd7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -337,6 +337,7 @@ struct kvm_vcpu_arch { unsigned int time_offset; struct page *time_page; u64 last_host_tsc; + u64 last_host_ns; bool nmi_pending; bool nmi_injected; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 618c435..b1bdf05 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1810,6 +1810,19 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* Make sure TSC doesn't go backwards */ s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 : native_read_tsc() - vcpu->arch.last_host_tsc; + + /* Subtract elapsed cycle time from the delta computation */ + if (check_tsc_unstable() && vcpu->arch.last_host_ns) { + s64 delta; + struct timespec ts; + ktime_get_ts(&ts); + monotonic_to_bootbased(&ts); + delta = timespec_to_ns(&ts) - vcpu->arch.last_host_ns; + delta = delta * per_cpu(cpu_tsc_khz, cpu); + delta = delta / USEC_PER_SEC; + tsc_delta -= delta; + } + if (tsc_delta < 0 || check_tsc_unstable()) kvm_x86_ops->adjust_tsc_offset(vcpu, -tsc_delta); kvm_migrate_timers(vcpu); @@ -1832,8 +1845,13 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) * vcpu->cpu != cpu can not detect this condition. So set * vcpu->cpu = -1 to force the recalibration above. */ - if (check_tsc_unstable()) + if (check_tsc_unstable()) { + struct timespec ts; + ktime_get_ts(&ts); + monotonic_to_bootbased(&ts); + vcpu->arch.last_host_ns = timespec_to_ns(&ts); vcpu->cpu = -1; + } } static int is_efer_nx(void)