Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752791AbaGBJRI (ORCPT ); Wed, 2 Jul 2014 05:17:08 -0400 Received: from goliath.siemens.de ([192.35.17.28]:41788 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752643AbaGBJRE (ORCPT ); Wed, 2 Jul 2014 05:17:04 -0400 Message-ID: <53B3CDFE.20808@siemens.com> Date: Wed, 02 Jul 2014 11:16:46 +0200 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: "Hu, Robert" , Wanpeng Li , Paolo Bonzini , Gleb Natapov CC: "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since race References: <1404284054-51863-1-git-send-email-wanpeng.li@linux.intel.com> <9E79D1C9A97CFD4097BCE431828FDD31983416@SHSMSX103.ccr.corp.intel.com> <53B3CADD.3000504@siemens.com> <9E79D1C9A97CFD4097BCE431828FDD3198359C@SHSMSX103.ccr.corp.intel.com> In-Reply-To: <9E79D1C9A97CFD4097BCE431828FDD3198359C@SHSMSX103.ccr.corp.intel.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014-07-02 11:13, Hu, Robert wrote: > >> -----Original Message----- >> From: Jan Kiszka [mailto:jan.kiszka@siemens.com] >> Sent: Wednesday, July 2, 2014 5:03 PM >> To: Hu, Robert; Wanpeng Li; Paolo Bonzini; Gleb Natapov >> Cc: kvm@vger.kernel.org; linux-kernel@vger.kernel.org >> Subject: Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since >> race >> >> On 2014-07-02 09:20, Hu, Robert wrote: >>>> -----Original Message----- >>>> From: Wanpeng Li [mailto:wanpeng.li@linux.intel.com] >>>> Sent: Wednesday, July 2, 2014 2:54 PM >>>> To: Paolo Bonzini; Jan Kiszka; Gleb Natapov >>>> Cc: Hu, Robert; kvm@vger.kernel.org; linux-kernel@vger.kernel.org; Wanpeng >> Li >>>> Subject: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since >> race >>>> >>>> This patch fix bug https://bugzilla.kernel.org/show_bug.cgi?id=72381 >>>> >>>> If we didn't inject a still-pending event to L1 since nested_run_pending, >>>> KVM_REQ_EVENT should be requested after the vmexit in order to inject the >>>> event to L1. However, current log blindly request a KVM_REQ_EVENT even if >>>> there is no still-pending event to L1 which blocked by nested_run_pending. >>>> There is a race which lead to an interrupt will be injected to L2 which >>>> belong to L1 if L0 send an interrupt to L1 during this window. >>>> >>>> VCPU0 another thread >>>> >>>> L1 intr not blocked on L2 first entry >>>> vmx_vcpu_run req event >>>> kvm check request req event >>>> check_nested_events don't have any intr >>>> not nested exit >>>> intr occur (8254, lapic timer >>>> etc) >>>> inject_pending_event now have intr >>>> inject interrupt >>>> >>>> This patch fix this race by introduced a l1_events_blocked field in nested_vmx >>>> which indicates there is still-pending event which blocked by >>>> nested_run_pending, >>>> and smart request a KVM_REQ_EVENT if there is a still-pending event which >>>> blocked >>>> by nested_run_pending. >>>> >>>> Signed-off-by: Wanpeng Li >>> Tested-by: Robert Hu >> >> Do you happen to have a kvm-unit-test for this race? Or how did you >> test? Just curious, and if there is a test, it would be good to >> integrate it. > I just apply the patch and test the reported scenario. Ah, sorry, missed the referenced bug report. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/