From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <ferruh.yigit@intel.com> Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id 3A18F3005 for <dev@dpdk.org>; Wed, 16 Dec 2015 05:04:13 +0100 (CET) Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga102.fm.intel.com with ESMTP; 15 Dec 2015 20:04:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,435,1444719600"; d="scan'208";a="842109466" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by orsmga001.jf.intel.com with ESMTP; 15 Dec 2015 20:04:11 -0800 Received: from sivlogin002.ir.intel.com (sivlogin002.ir.intel.com [10.237.217.37]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id tBG44AR3030529; Wed, 16 Dec 2015 04:04:10 GMT Received: from sivlogin002.ir.intel.com (localhost [127.0.0.1]) by sivlogin002.ir.intel.com with ESMTP id tBG4493D022736; Wed, 16 Dec 2015 04:04:09 GMT Received: (from fyigit@localhost) by sivlogin002.ir.intel.com with œ id tBG449ug022732; Wed, 16 Dec 2015 04:04:09 GMT X-Authentication-Warning: sivlogin002.ir.intel.com: fyigit set sender to ferruh.yigit@intel.com using -f Date: Wed, 16 Dec 2015 04:04:08 +0000 From: Ferruh Yigit <ferruh.yigit@intel.com> To: Alex Williamson <alex.williamson@redhat.com> Message-ID: <20151216040408.GA18363@sivlogin002.ir.intel.com> Mail-Followup-To: Alex Williamson <alex.williamson@redhat.com>, "O'Driscoll, Tim" <tim.odriscoll@intel.com>, Vincent JARDIN <vincent.jardin@6wind.com>, "dev@dpdk.org" <dev@dpdk.org> References: <60420822.AbcfvjLZCk@xps13> <566B4A50.9090607@6wind.com> <1449874953.20509.6.camel@redhat.com> <26FA93C7ED1EAA44AB77D62FBE1D27BA6747CE55@IRSMSX108.ger.corp.intel.com> <1450198398.6042.32.camel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1450198398.6042.32.camel@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: "dev@dpdk.org" <dev@dpdk.org> Subject: Re: [dpdk-dev] VFIO no-iommu X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK <dev.dpdk.org> List-Unsubscribe: <http://dpdk.org/ml/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://dpdk.org/ml/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <http://dpdk.org/ml/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Wed, 16 Dec 2015 04:04:13 -0000 On Tue, Dec 15, 2015 at 09:53:18AM -0700, Alex Williamson wrote: > On Tue, 2015-12-15 at 13:43 +0000, O'Driscoll, Tim wrote: > > > -----Original Message----- > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Alex > > > Williamson > > > Sent: Friday, December 11, 2015 11:03 PM > > > To: Vincent JARDIN; dev@dpdk.org > > > Subject: Re: [dpdk-dev] VFIO no-iommu > > > > > > On Fri, 2015-12-11 at 23:12 +0100, Vincent JARDIN wrote: > > > > Thanks Thomas for putting back this topic. > > > > > > > > Alex, > > > > > > > > I'd like to hear more about the impacts of "unsupported": > > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/c > > > > ommi > > > > t/?id=033291eccbdb1b70ffc02641edae19ac825dc75d > > > > Use of this mode, specifically binding a device without a > > > > native > > > > IOMMU group to a VFIO bus driver will taint the kernel and > > > > should > > > > therefore not be considered supported. > > > > > > > > It means that we get ride of uio; so it is a nice code cleanup: > > > > but > > > > why > > > > would VFIO/NO IOMMU be better if the bottomline is "unsupported"? > > > > > > How supportable do you think the uio method is? Fundamentally we > > > have > > > a userspace driver doing unrestricted DMA; it can access and modify > > > any > > > memory in the system. This is the reason uio won't provide a > > > mechanism > > > to enable MSI and if you ask the uio maintainer, they don't support > > > DMA > > > at all, it's only intended as a programmed IO interface to the > > > device. > > > Unless we can sandbox a user owned device within an IOMMU > > > protected > > > container, it's not supportable. The VFIO no-iommu mode can simply > > > provide you that unsupported mode more easily since it leverages > > > code > > > from the supported mode, which is IOMMU protected. Thanks, > > > > Thanks for clarifying. > > > > This does seem like it would be useful for DPDK. We're doing some > > further investigation to see if it works out of the box with DPDK or > > if we need to make any changes to support it. > > The iommu model is different, there's no type1 interface available when > using this mode since we have no ability to provide translation. The > no-iommu iommu model really does nothing, which is a possible issue for > userspace. Is it sufficient? We stopped short of creating a page > pinning interface through the no-iommu model because it requires code > and adding piles of new code for an interface we claim is unsupported > doesn't make a lot of sense. The device interface should be identical > to existing vfio support. > > > Thomas highlighted that your original commit for this had been > > reverted. What specifically would you need from us in order to re- > > submit the VFIO No-IOMMU support? > > No API changes should ever go into the kernel without being validated > by a user. Without that we're risking that the kernel interface is > broken and we're stuck supporting it. In this case I tried to make > sure we had a working user before it went it, gambled that it was close > enough to put in anyway, then paid the price when development went > silent on the user side. To get it back in, I'm going to need a > working use first. You can re-apply 033291eccbdb or re- > revert ae5515d66362 for development of that. I need to see that it > works and that there's some consensus from the dpdk community that it's > a worthwhile path forward for cases without an iommu. There's no point > in merging it if it only becomes a userspace proof of concept. Thanks, > I tested the DPDK (HEAD of master) with the patch, with help of Anatoly, and DPDK works in no-iommu environment with a little modification. Basically the only modification is adapt new group naming (noiommu-$) and disable dma mapping (VFIO_IOMMU_MAP_DMA) Also I need to disable VFIO_CHECK_EXTENSION ioctl, because in vfio module, container->noiommu is not set before doing a vfio_group_set_container() and vfio_for_each_iommu_driver selects wrong driver. What I test is bind two different type of NICs into VFIO driver, and use testpmd to confirm transfer is working. Kernel booted without iommu enabled, vfio module inserted with "enable_unsafe_noiommu_support" parameter. Thanks, ferruh