Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757577Ab0DOI5y (ORCPT ); Thu, 15 Apr 2010 04:57:54 -0400 Received: from mga05.intel.com ([192.55.52.89]:42126 "EHLO fmsmga101.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757449Ab0DOI5w (ORCPT ); Thu, 15 Apr 2010 04:57:52 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,211,1270450800"; d="scan'208";a="558173466" Subject: Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side From: "Zhang, Yanmin" To: Avi Kivity Cc: Ingo Molnar , Peter Zijlstra , Sheng Yang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marcelo Tosatti , oerg Roedel , Jes Sorensen , Gleb Natapov , Zachary Amsden , zhiteng.huang@intel.com, tim.c.chen@intel.com, Arnaldo Carvalho de Melo In-Reply-To: <4BC6C8CD.1020801@redhat.com> References: <1902387910.2078.435.camel@ymzhang.sh.intel.com> <4BC588CF.5010507@redhat.com> <1902445479.2078.458.camel@ymzhang.sh.intel.com> <4BC6C8CD.1020801@redhat.com> Content-Type: text/plain; charset="ISO-8859-1" Date: Mon, 15 Apr 2030 16:57:38 +0800 Message-Id: <1902473858.2078.481.camel@ymzhang.sh.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.0 (2.28.0-2.fc12) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1797 Lines: 44 On Thu, 2010-04-15 at 11:05 +0300, Avi Kivity wrote: > On 04/15/2030 04:04 AM, Zhang, Yanmin wrote: > > > >> An even more accurate way to determine this is to check whether the > >> interrupt frame points back at the 'int $2' instruction. However we > >> plan to switch to a self-IPI method to inject the NMI, and I'm not sure > >> wether APIC NMIs are accepted on an instruction boundary or whether > >> there's some latency involved. > >> > > Yes. But the frame pointer checking seems a little complicated. > > > > An even bigger disadvantage is that it won't work with Sheng's patch, > self-NMIs are not synchronous. > > >>> trace_kvm_entry(vcpu->vcpu_id); > >>> + > >>> + percpu_write(current_vcpu, vcpu); > >>> kvm_x86_ops->run(vcpu); > >>> + percpu_write(current_vcpu, NULL); > >>> > >>> > >> If you move this around the 'int $2' instructions you will close the > >> race, as a stray NMI won't catch us updating the rip cache. But that > >> depends on whether self-IPI is accepted on the next instruction or not. > >> > > Right. The kernel part has dependency on the self-IPI implementation. > > I will move above percpu_write(current_vcpu, vcpu) (or a new wrapper function) > > just around 'int $2'. > > > > > > Or create a new function to inject the interrupt in x86.c. That will > reduce duplication between svm.c and vmx.c. I checked svm.c and it seems svm.c doesn't trigger a NMI to host if the NMI happens in guest os. In addition, svm_complete_interrupts is called after interrupt is enabled. -- 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/