From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: nmi is broken? Date: Wed, 27 Apr 2011 14:09:00 +0200 Message-ID: <4DB8075C.2050407@siemens.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: OGAWA Hirofumi , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from goliath.siemens.de ([192.35.17.28]:34236 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755561Ab1D0MJJ (ORCPT ); Wed, 27 Apr 2011 08:09:09 -0400 In-Reply-To: <4DB7DA11.8040503@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2011-04-27 10:55, Avi Kivity wrote: > On 04/24/2011 03:24 PM, Jan Kiszka wrote: >> > >> > This would cause IRQs to be delivered even if the PIT is masked, no? >> >> I checked the patch and our code again: NMI watchdog masking is managed >> via arch.vapics_in_nmi_mode and by re-checking the per-APIC mask >> situation in kvm_apic_local_deliver when delivering the NMI. >> >> So the patch looks correct - NMIs aren't acked like timer IRQs, the >> current logic is definitely wrong. > > Can you elaborate? Why aren't NMIs acked (if delivered via the PIC)? > Is the PIC programmed into auto-EOI mode or something? At least there are no traces of 8259 interaction in the NMI handler of old kernels when configured to IOAPIC mode. This wouldn't work anyway as you can't synchronize with other PIC-accessing functions from the NMI handler. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux