From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] KVM: nVMX: Fix IRQs inject to L2 which belong to L1 since race Date: Wed, 02 Jul 2014 11:03:25 +0200 Message-ID: <53B3CADD.3000504@siemens.com> References: <1404284054-51863-1-git-send-email-wanpeng.li@linux.intel.com> <9E79D1C9A97CFD4097BCE431828FDD31983416@SHSMSX103.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: "Hu, Robert" , Wanpeng Li , Paolo Bonzini , Gleb Natapov Return-path: In-Reply-To: <9E79D1C9A97CFD4097BCE431828FDD31983416@SHSMSX103.ccr.corp.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux