From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [PATCH 0/8][v2] MSI-X mask emulation support for assigned device Date: Wed, 20 Oct 2010 08:58:38 -0600 Message-ID: <1287586718.3007.19.camel@x201> References: <1287563192-29685-1-git-send-email-sheng@linux.intel.com> <4CBEBB85.4000706@redhat.com> <20101020104447.GD12878@redhat.com> <4CBECB9E.7000005@redhat.com> <20101020134329.GB13311@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Sheng Yang , Marcelo Tosatti , kvm@vger.kernel.org To: "Michael S. Tsirkin" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:26557 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028Ab0JTO6l (ORCPT ); Wed, 20 Oct 2010 10:58:41 -0400 In-Reply-To: <20101020134329.GB13311@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, 2010-10-20 at 15:43 +0200, Michael S. Tsirkin wrote: > On Wed, Oct 20, 2010 at 12:59:42PM +0200, Avi Kivity wrote: > > How far away is vfio? If it's merged soon, we might avoid making > > changes to the old assigned device infrastructure and instead update > > vfio. > > Hard to be sure, hopefully 2.6.38 material. > > Some issues off the top of my head are > - readonly/virtualized table correctness > hopefully will start converging now that > we are switching to standard registers from pci_regs.h > - work out some capability negotiation mechanism so userspace/kernel > can detect bug fixes/missing features and recover or fail gracefully > - with multiple assigned devices in a guest: > I don't think we have figured out how do they share an iommu context A single UIOMMU fd can be used for multiple devices. The code I wrote supports this, but it's really only meant to support a uiommufd passed via the command line for libvirt usage. Since libvirt doesn't yet support vfio, it's never been tested. > - maybe: reset handling (flr support) - need to look a it I'd add that for the qemu vfio driver, we need to work out the KVM interrupt optimizations, otherwise we suffer extra latency vs current code. > > > On the other hand, changes to the old infrastructure are much > > more amenable to backporting for long term support distro kernels, > > so we may need to actively develop both for a while. Yep, I think we'll need to continue development and probably maintain them both for a while. Alex