From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC PATCH] kvm: Extend irqfd to support level interrupts Date: Sun, 17 Jun 2012 21:44:51 +0300 Message-ID: <20120617184451.GD21231@redhat.com> References: <20120616163230.15204.61075.stgit@bling.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: avi@redhat.com, mtosatti@redhat.com, kvm@vger.kernel.org, jan.kiszka@siemens.com To: Alex Williamson Return-path: Received: from mx1.redhat.com ([209.132.183.28]:25634 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757473Ab2FQSo5 (ORCPT ); Sun, 17 Jun 2012 14:44:57 -0400 Content-Disposition: inline In-Reply-To: <20120616163230.15204.61075.stgit@bling.home> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, Jun 16, 2012 at 10:34:39AM -0600, Alex Williamson wrote: > I'm looking for opinions on this approach. For vfio device assignment > we minimally need a way to get EOIs from the in-kernel irqchip out to > userspace. Getting that out via an eventfd would allow us to bounce > all level interrupts out to userspace, where we would de-assert the > device interrupt in qemu and unmask the physical device. Ideally we > could deassert the interrupt in KVM, which allows us to send the EOI > directly to vfio. To do that, we need to use a new IRQ source ID so > the guest sees the logical OR of qemu requested state and external > device state. Given that yopu want to involve userspace anyway, why insist on irqfd for this? You can simply use KVM_IRQ_LINE_STATUS from qemu, no? -- MST