From patchwork Sun Nov 5 14:11:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liran Alon X-Patchwork-Id: 10042199 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B5CEC6037D for ; Sun, 5 Nov 2017 14:11:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A75032923E for ; Sun, 5 Nov 2017 14:11:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9AE8229382; Sun, 5 Nov 2017 14:11:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2D1992923E for ; Sun, 5 Nov 2017 14:11:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751172AbdKEOLv (ORCPT ); Sun, 5 Nov 2017 09:11:51 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:50801 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751041AbdKEOLu (ORCPT ); Sun, 5 Nov 2017 09:11:50 -0500 Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id vA5EBlfQ007856 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 5 Nov 2017 14:11:48 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id vA5EBlc2014194 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 5 Nov 2017 14:11:47 GMT Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id vA5EBlbx026005; Sun, 5 Nov 2017 14:11:47 GMT Received: from liran-pc.ravello.local (/213.57.127.2) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 05 Nov 2017 06:11:47 -0800 From: Liran Alon To: pbonzini@redhat.com, rkrcmar@redhat.com, kvm@vger.kernel.org Cc: idan.brown@oracle.com, Liran Alon , Konrad Rzeszutek Wilk Subject: [PATCH] KVM: x86: pvclock: Handle first-time write to pvclock-page contains random junk Date: Sun, 5 Nov 2017 16:11:30 +0200 Message-Id: <1509891090-8985-1-git-send-email-liran.alon@oracle.com> X-Mailer: git-send-email 1.9.1 X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When guest passes KVM it's pvclock-page GPA via WRMSR to MSR_KVM_SYSTEM_TIME / MSR_KVM_SYSTEM_TIME_NEW, KVM don't initialize pvclock-page to some start-values. It just requests a clock-update which will happen before entering to guest. The clock-update logic will call kvm_setup_pvclock_page() to update the pvclock-page with info. However, kvm_setup_pvclock_page() *wrongly* assumes that the version-field is initialized to an even number. This is wrong because at first-time write, field could be any-value. Fix simply makes sure that if first-time version-field is odd, increment it once more to make it even and only then start standard logic. This follows same logic as done in other pvclock shared-pages (See kvm_write_wall_clock() and record_steal_time()). Signed-off-by: Liran Alon Reviewed-by: Nikita Leshenko Reviewed-by: Konrad Rzeszutek Wilk Signed-off-by: Konrad Rzeszutek Wilk Reviewed-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 03869eb7fcd6..181106080e41 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1830,6 +1830,9 @@ static void kvm_setup_pvclock_page(struct kvm_vcpu *v) */ BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0); + if (guest_hv_clock.version & 1) + ++guest_hv_clock.version; /* first time write, random junk */ + vcpu->hv_clock.version = guest_hv_clock.version + 1; kvm_write_guest_cached(v->kvm, &vcpu->pv_time, &vcpu->hv_clock,