From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by ozlabs.org (Postfix) with ESMTP id E22D1B6F85 for ; Tue, 2 Aug 2011 04:00:25 +1000 (EST) Subject: Re: kvm PCI assignment & VFIO ramblings From: Alex Williamson To: Benjamin Herrenschmidt Date: Mon, 01 Aug 2011 10:40:46 -0600 In-Reply-To: <1312064479.8793.739.camel@pasglop> References: <1311983933.8793.42.camel@pasglop> <1312064479.8793.739.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Message-ID: <1312216847.2653.258.camel@bling.home> Mime-Version: 1.0 Cc: Alexey Kardashevskiy , kvm@vger.kernel.org, Paul Mackerras , "linux-pci@vger.kernel.org" , David Gibson , Anthony Liguori , linuxppc-dev List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, 2011-07-31 at 08:21 +1000, Benjamin Herrenschmidt wrote: > On Sat, 2011-07-30 at 09:58 +1000, Benjamin Herrenschmidt wrote: > > Hi folks ! > > > > So I promised Anthony I would try to summarize some of the comments & > > issues we have vs. VFIO after we've tried to use it for PCI pass-through > > on POWER. It's pretty long, there are various items with more or less > > impact, some of it is easily fixable, some are API issues, and we'll > > probably want to discuss them separately, but for now here's a brain > > dump. > > > > David, Alexei, please make sure I haven't missed anything :-) > > And I think I have :-) > > * Config space > > VFIO currently handles that as a byte stream. It's quite gross to be > honest and it's not right. You shouldn't lose access size information > between guest and host when performing real accesses. > > Some config space registers can have side effects and not respecting > access sizes can be nasty. It's a bug, let's fix it. Alex