From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [RFC PATCH 0/4] MSI affinity for assigned devices Date: Tue, 27 Nov 2012 16:21:02 -0700 Message-ID: <1354058462.1809.182.camel@bling.home> References: <20121127215203.5751.6523.stgit@bling.home> <50B547F3.1080907@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58903 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755764Ab2K0XVK (ORCPT ); Tue, 27 Nov 2012 18:21:10 -0500 In-Reply-To: <50B547F3.1080907@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, 2012-11-28 at 00:08 +0100, Jan Kiszka wrote: > On 2012-11-27 23:00, Alex Williamson wrote: > > This is post-1.3 material, so I'll just post it as an RFC for now. > > > > MSI routing updates aren't currently handled by pci-assign or > > vfio-pci (when using KVM acceleration), which means that trying to > > set interrupt SMP affinity in the guest has no effect unless MSI is > > completely disabled and re-enabled. This series fixes this for both > > device assignment backends using similar schemes. We store the last > > MSIMessage programmed to KVM and do updates to the MSI route when it > > changes. pci-assign takes a little bit of refactoring to make this > > happen cleanly. Thanks, > > This should rather be done by implementing vector notifiers for MSI as > well. That way the device model no longer has to track reasons for > vector changes in an open-coded fashion, just like we already do for MSI-X. > > Was on my todo list for a long time, but I never reached this item. MSI masking is optional and not many devices seem to support it. What I see with a linux guest is that it just overwrites the address/data while MSI is enabled. What were you thinking for notifiers? mask, unmask, update? I'm not sure I'm interested enough in this to add MSI vector notifiers. Thanks, Alex