From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [RFC PATCH] qemu pci: pci_add_capability enhancement to prevent damaging config space Date: Fri, 08 Jun 2012 09:22:00 -0600 Message-ID: <1339168920.26976.86.camel@ul30vt> References: <4FACB581.2050609@ozlabs.ru> <6A22E211-BC82-49BD-A335-02D3BAA14A17@suse.de> <4FAD0A4F.2050506@ozlabs.ru> <4FB080CE.3030703@ozlabs.ru> <4FB5DA43.90907@ozlabs.ru> <1337652170.2779.143.camel@pasglop> <6C472F5B-B8C3-48DE-B19B-00973AF6AC56@suse.de> <4FBB0B95.8050901@ozlabs.ru> <82643009-4F43-407F-B26C-C36537825BFD@suse.de> <4FBB2E25.2030206@ozlabs.ru> <584A5E54-2119-415C-93B4-BB91A08CA729@suse.de> <4FD1BC14.6030900@ozlabs.ru> <4FD1DA5C.5020900@siemens.com> <4FD1DF29.1050303@ozlabs.ru> <4FD1E25A.2010900@siemens.com> <4FD2058F.7030903@ozlabs.ru> <4FD20F92.9080805@siemens.com> <1339167384.26976.71.camel@ul30vt> <4FD214C3.90507@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Alexey Kardashevskiy , Alexander Graf , "kvm@vger.kernel.org" , "qemu-devel@nongnu.org" , "anthony@codemonkey.ws" , David Gibson To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:14232 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761079Ab2FHPWN (ORCPT ); Fri, 8 Jun 2012 11:22:13 -0400 In-Reply-To: <4FD214C3.90507@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, 2012-06-08 at 17:05 +0200, Jan Kiszka wrote: > On 2012-06-08 16:56, Alex Williamson wrote: > > The difference between VFIO and kvm device assignment is that VFIO > > emulates a lot of config space for us, so most things are passed > > through. > > That's not different from current device assignment, is it? I think the > major difference is that VFIO filters and potentially post-processes the > direct writes in kernel space. Right, and having the filtering/virtualization in the kernel means that qemu only handles a very small subset of PCI config space. That's made us lax in even telling qemu about the areas that it'll never see accesses too. For current device assignment, since we doing the emulation in qemu, it's a little more beneficial to register everything. Thanks, Alex