Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932373AbbBZXmL (ORCPT ); Thu, 26 Feb 2015 18:42:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50478 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753643AbbBZXmJ (ORCPT ); Thu, 26 Feb 2015 18:42:09 -0500 Date: Thu, 26 Feb 2015 20:41:14 -0300 From: Marcelo Tosatti To: "Wu, Feng" Cc: "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "gleb@kernel.org" , "pbonzini@redhat.com" , "dwmw2@infradead.org" , "joro@8bytes.org" , "alex.williamson@redhat.com" , "jiang.liu@linux.intel.com" , "eric.auger@linaro.org" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "Zhang, Yang Z" Subject: Re: [v3 24/26] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked Message-ID: <20150226234114.GB7784@amt.cnet> References: <1418397300-10870-1-git-send-email-feng.wu@intel.com> <1418397300-10870-25-git-send-email-feng.wu@intel.com> <20150225215011.GA16848@amt.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2110 Lines: 58 On Thu, Feb 26, 2015 at 08:08:15AM +0000, Wu, Feng wrote: > > > > -----Original Message----- > > From: Marcelo Tosatti [mailto:mtosatti@redhat.com] > > Sent: Thursday, February 26, 2015 5:50 AM > > To: Wu, Feng > > Cc: tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; x86@kernel.org; > > gleb@kernel.org; pbonzini@redhat.com; dwmw2@infradead.org; > > joro@8bytes.org; alex.williamson@redhat.com; jiang.liu@linux.intel.com; > > eric.auger@linaro.org; linux-kernel@vger.kernel.org; > > iommu@lists.linux-foundation.org; kvm@vger.kernel.org > > Subject: Re: [v3 24/26] KVM: Update Posted-Interrupts Descriptor when vCPU > > is blocked > > > > On Fri, Dec 12, 2014 at 11:14:58PM +0800, Feng Wu wrote: > > > This patch updates the Posted-Interrupts Descriptor when vCPU > > > is blocked. > > > > > > pre-block: > > > - Add the vCPU to the blocked per-CPU list > > > - Clear 'SN' > > > - Set 'NV' to POSTED_INTR_WAKEUP_VECTOR > > > > > > post-block: > > > - Remove the vCPU from the per-CPU list > > > > > > Signed-off-by: Feng Wu > > > --- > > > > Don't see this is needed, can use the existing POSTED_INTR_VECTOR: > > > > If in guest mode, IPI will be handled in VMX non-root by performed > > PIR->IRR transfer. > > > > If outside guest mode, POSTED_INTR_VECTOR IPI will be handled by host > > which can wakeup the guest (in case it is halted). > > Please see the following scenario: > > 1. vCPU0 is running on pCPU0 > 2. vCPU0 is halted and vCPU1 is currently running on pCPU0 > 3. An interrupt occurs for vCPU0, if we still use POSTED_INTR_VECTOR > for vCPU0, the notification event for vCPU0 (the event will go to pCPU1) > will be consumed by vCPU1 incorrectly. The worst case is that vCPU0 > will never be woken up again since the wakeup event for it is always > consumed by other vCPUs incorrectly. > > Thanks, > Feng Ouch, yes. -- 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/