From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH 0/4] Add posted interrupt supporting Date: Wed, 10 Apr 2013 09:42:44 -0400 Message-ID: <20130410134244.GB5686@phenom.dumpdata.com> References: <1365487291-2283-1-git-send-email-yang.z.zhang@intel.com> <20130409202640.GA2509@phenom.dumpdata.com> <20130410132208.GF4865@phenom.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Zhang, Yang Z" Cc: "keir.xen@gmail.com" , "Zhang, Xiantao" , "JBeulich@suse.com" , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On Wed, Apr 10, 2013 at 01:32:41PM +0000, Zhang, Yang Z wrote: > Konrad Rzeszutek Wilk wrote on 2013-04-10: > > On Wed, Apr 10, 2013 at 02:51:41AM +0000, Zhang, Yang Z wrote: > >> Konrad Rzeszutek Wilk wrote on 2013-04-10: > >>> On Tue, Apr 09, 2013 at 02:01:27PM +0800, Yang Zhang wrote: > >>>> From: Yang Zhang > >>>> > >>>> The follwoing patches are adding the Posted Interrupt supporting to Xen: > >>>> Posted Interrupt allows vAPIC interrupts to inject into guest directly > >>>> without any vmexit. > >>> > >>> Is there a mechanism for the guest to figure out whether this is exported? > >> Expose it to guest? No. > >> > >>> > >>> Right now the Linux PVHVM guests will use the event channel mechanism > >>> (via the 0xf3 callback vector). This means that if we want to do IPIs > >>> (RESCHEDULE_VECTOR or CALL_FUNCTION_*) we end up doing a vmexit - but > >>> with this we should be able to do these inside the guest right? > >> I am not familiar with PV staffs. Will event channel mechanism touch vAPIC? If > > no, perhaps the answer is not. > > > > No it won't. But any any inter-OS vectors (such as IPIs) would benefit > > from vAPIC right? As in posting those vectors (assuming the destination > > VCPU is running) would not cause an VMEXIT? > Yes. > > >> > >>> > >>> If so, is there a mechanism inside the guest to detect this and > >>> use the HVM mechanisms for IPI? > >> Why guest should aware of this? Current implementation already covers the > > vIPI. > > > > Not sure I understand you. What current implementation? > I thought you mean the vIPI. Obviously, I am wrong. :( > What does " HVM mechanisms for IPI " mean? '__default_send_IPI_dest_field' in the Linux code, which is writting in the ICR2 field in the APIC.