From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 5/5] Fix kdump under KVM. Date: Tue, 27 Oct 2009 15:42:46 -0200 Message-ID: <20091027174246.GA10473@amt.cnet> References: <1256661667-9298-1-git-send-email-clalance@redhat.com> <1256661667-9298-6-git-send-email-clalance@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: Chris Lalancette Return-path: Received: from mx1.redhat.com ([209.132.183.28]:9452 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752446AbZJ0Rnu (ORCPT ); Tue, 27 Oct 2009 13:43:50 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n9RHhs1R017337 for ; Tue, 27 Oct 2009 13:43:55 -0400 Content-Disposition: inline In-Reply-To: <1256661667-9298-6-git-send-email-clalance@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Oct 27, 2009 at 05:41:07PM +0100, Chris Lalancette wrote: > This patch is the main point of the series. In order for > kdump to properly work inside a KVM guest, we need to make > sure that all VCPUs in virtual wire APIC mode get kicked > to try and pick up the timer interrupts. To do this, > we iterate over the CPUs and deliver interrupts to the > proper VCPUs. > > I don't love the concept of doing kvm_irq_kick_vcpus() from > within pit_timer_fn(). A PIT is not connected to a CPU at all, > only to a PIC or APIC. However, if a CPU enters idle, this is > the only way to wake it up to check for the interrupt. The reason the PIT interrupt was fixed to BSP is: http://www.mail-archive.com/kvm-devel@lists.sourceforge.net/msg13250.html Perhaps enhancing ioapic_deliver's (irq == 0) check to bypass the destination overwrite in case its programmed by the guest to a single CPU would fix it?