From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v2] KVM: Implement support for the RH bit Date: Fri, 2 Sep 2011 18:03:39 +0300 Message-ID: <20110902150339.GI26451@redhat.com> References: <4E60BFD9.6090507@siemens.com> <4E60C7EB.9060401@siemens.com> <1314969237.31676.4.camel@lappy> <4E60E193.1050804@siemens.com> <1314972661.31676.11.camel@lappy> <4E60E767.7060404@siemens.com> <1314973858.31676.16.camel@lappy> <4E60E9FE.60608@siemens.com> <20110902144422.GH26451@redhat.com> <4E60EDC3.1050908@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sasha Levin , "kvm@vger.kernel.org" , Avi Kivity , Marcelo Tosatti , "Tian, Kevin" To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:21798 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752954Ab1IBPDp (ORCPT ); Fri, 2 Sep 2011 11:03:45 -0400 Content-Disposition: inline In-Reply-To: <4E60EDC3.1050908@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Sep 02, 2011 at 04:52:51PM +0200, Jan Kiszka wrote: > >> That's debatable. delivery_mode == APIC_DM_LOWEST includes this target > >> selection, but also more. I have a bad feeling when we just overwrite > >> delivery_mode as defined by the MSI data field instead of only patching > >> kvm_irq_delivery_to_apic or kvm_is_dm_lowest_prio - if required. > >> > > Patching them how? To behave exactly like delivery_mode == APIC_DM_LOWEST in > > case RH bit is set? Then setting delivery_mode to APIC_DM_LOWEST will > > achieve the same goal. > > /Wrt selecting the target CPU, but not regarding the vector type > delivered to that CPU (think of obscure things like RH=1, > delivery_mode=APIC_DM_NMI). If RH=1 only meant hard-wiring delivery_mode > to single value, then this would be redundant encoding. And that's > always suspicious (unless there is legacy involved). > Hmm, good point. -- Gleb.