From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback Date: Sun, 11 Jul 2010 21:30:59 +0300 Message-ID: <4C3A0DE3.8010806@redhat.com> References: <20100711180910.20121.93313.stgit@localhost6.localdomain6> <20100711180936.20121.35376.stgit@localhost6.localdomain6> <4C3A09F3.8010304@redhat.com> <1278872784.20397.18.camel@x201> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org, pugs@cisco.com, chrisw@redhat.com, mst@redhat.com To: Alex Williamson Return-path: Received: from mx1.redhat.com ([209.132.183.28]:64822 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754267Ab0GKSbF (ORCPT ); Sun, 11 Jul 2010 14:31:05 -0400 In-Reply-To: <1278872784.20397.18.camel@x201> Sender: kvm-owner@vger.kernel.org List-ID: On 07/11/2010 09:26 PM, Alex Williamson wrote: > On Sun, 2010-07-11 at 21:14 +0300, Avi Kivity wrote: > >> On 07/11/2010 09:09 PM, Alex Williamson wrote: >> >>> For device assignment, we need to know when the VM writes an end >>> of interrupt to the APIC, which allows us to de-assert the interrupt >>> line and clear the DisINTx bit. Add a new wrapper for ioapic >>> generated interrupts with a callback on eoi and create an interface >>> for drivers to be notified on eoi. >>> >>> >> You aren't going to get this with kvm's in-kernel irqchip, so we need a >> new interface there. >> > Registering an eventfd for the eoi seems like a reasonable alternative. > I'm worried about that racing (with what?) > I also need to figure out how to avoid bouncing the vfio interrupt > events through qemu, but it's a functional start. Thanks, > I thought the scheduler has/wants to have something that moves the irq to whatever thread it wakes up. With irqfd, it would flow naturally. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.