From mboxrd@z Thu Jan 1 00:00:00 1970 From: OGAWA Hirofumi Subject: Re: nmi is broken? Date: Sun, 01 May 2011 10:45:39 +0900 Message-ID: <87mxj7urb0.fsf@devron.myhome.or.jp> References: <87sjtbe7fz.fsf@devron.myhome.or.jp> <877hak1t1s.fsf@devron.myhome.or.jp> <4DB3C6D3.9040703@redhat.com> <4DB41696.6060606@web.de> <4DB7DA11.8040503@redhat.com> <871v0njhab.fsf@devron.myhome.or.jp> <4DB93A6D.3010703@redhat.com> <87sjt2ij8b.fsf@devron.myhome.or.jp> <87k4eeihdu.fsf@devron.myhome.or.jp> Mime-Version: 1.0 Content-Type: text/plain Cc: Jan Kiszka , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail.parknet.co.jp ([210.171.160.6]:43121 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756181Ab1EABpq (ORCPT ); Sat, 30 Apr 2011 21:45:46 -0400 In-Reply-To: <87k4eeihdu.fsf@devron.myhome.or.jp> (OGAWA Hirofumi's message of "Thu, 28 Apr 2011 23:23:57 +0900") Sender: kvm-owner@vger.kernel.org List-ID: OGAWA Hirofumi writes: >>> That is correct, kvm doesn't connect the master 8259 output to the >>> IOAPIC. Instead the 8259 is connected to LINT0 (which is configured for >>> ExtInt when the IOAPIC is disabled, or for NMI which the NMI watchdog is >>> enabled). >>> >>> However, now I can't see how it would work. auto EOI works on the INTA >>> cycle, which would only occur if LINT0 is configured for ExtInt. If it >>> is configured for NMI, I don't think it would issue the INTA cycle. So >>> the NMI watchdog not working is actually correct for our hardware >>> configuration! >>> >>> But I may be misunderstanding something here. >> >> I see. If the physical machine was configured as above, I guess (not >> pretty sure, I don't have this configuration machine), IOAPIC test >> (check_timer() in io_apic.c) should fail, and IOAPIC wouldn't have any >> effect. And I think MADT should tell mp_ExtINT. >> >> Yes, I also guess the above configuration wouldn't work NMI watchdog of >> IOAPIC mode, and linux will report as NMI watchdog can't work in >> check_timer(). > > Hm.., if smp was enabled, what configuration model is used by kvm? I > think this configuration model can't work on smp. As far as I can see, kvm is not configured (from MADT and some of behaviors) like you said. So, I think there are some solutions, a) current behavior is right (I don't know why it's right though), b) fix the behavior of IO-APIC and MADT like you said, then linux can detect it, c) change the model to like mpspec figure 5-2, d) other. My suggestion is c) if there is no good d). Because current behavior looks like almost c), and non-legacy chipsets are using c) model as far as I know. Thanks. -- OGAWA Hirofumi