From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934667AbXGRQl1 (ORCPT ); Wed, 18 Jul 2007 12:41:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933199AbXGRQlQ (ORCPT ); Wed, 18 Jul 2007 12:41:16 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:60990 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S933864AbXGRQlQ (ORCPT ); Wed, 18 Jul 2007 12:41:16 -0400 Date: Wed, 18 Jul 2007 17:47:36 +0100 From: Alan Cox To: "Dor Laor" Cc: "Or Sagi" , , Subject: Re: [kvm-devel] [RFC] Deferred interrupt handling. Message-ID: <20070718174736.0baf6d0e@the-village.bc.nu> In-Reply-To: <64F9B87B6B770947A9F8391472E032160CC16C92@ehost011-8.exch011.intermedia.net> References: <005901c7c921$79c006c0$6d401440$@com> <20070718123040.615795b7@the-village.bc.nu> <64F9B87B6B770947A9F8391472E032160CC16C92@ehost011-8.exch011.intermedia.net> X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.8; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > What if we will force the specific device to the end of the list. Once > IRQ_NONE was returned by the other devices, we will mask the irq, > forward the irq to the guest, issue a timer for 1msec. Motivation: > 1msec is long enough for the guest to ack the irq + host unmask the irq It makes no difference. The deadlock isn't fixable by timing hacks. Consider the following sequence Guest0 - blocked on I/O IRQ14 from your hardware Block IRQ14 Sent to guest (guest is blocked) IRQ14 from hard disk Ignored (as blocked) Deadlock