From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 14/21] KVM: x86: Software disabled APIC should still deliver NMIs Date: Thu, 06 Nov 2014 10:34:22 +0100 Message-ID: <545B409E.1020500@redhat.com> References: <1414922101-17626-1-git-send-email-namit@cs.technion.ac.il> <1414922101-17626-15-git-send-email-namit@cs.technion.ac.il> <545A1852.1000603@redhat.com> <5D182FD6-0365-4471-AD28-C587A624D151@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Nadav Amit , kvm@vger.kernel.org To: Nadav Amit Return-path: Received: from mail-wg0-f53.google.com ([74.125.82.53]:36658 "EHLO mail-wg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751210AbaKFJec (ORCPT ); Thu, 6 Nov 2014 04:34:32 -0500 Received: by mail-wg0-f53.google.com with SMTP id b13so683828wgh.26 for ; Thu, 06 Nov 2014 01:34:31 -0800 (PST) In-Reply-To: <5D182FD6-0365-4471-AD28-C587A624D151@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/11/2014 21:45, Nadav Amit wrote: > If I understand the SDM correctly, in such scenario (all APICs are > software disabled) the mode is left as the default - flat mode (see > section 10.6.2.2 "Logical Destination Mode=94): "All processors that > have their APIC software enabled (using the spurious vector > enable/disable bit) must have their DFRs (Destination Format > Registers) programmed identically. The default mode for DFR is flat > mode.=94 That's not what either Bochs or QEMU do, though. (Though in the case o= f Bochs I cannot find the place where reception of IPIs is prevented for software-disabled APICs, so I'm not sure how much to trust it in this c= ase). I'm not sure why software-disabled APICs could have different DFRs, if the APICs can receive NMI IPIs. I'll ask Intel. Paolo > So I think the previous behaviour (before the additional changes) is > the correct one. I might be able to confirm it, but anyhow only in a > couple of weeks.