From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48293) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fijyj-0001Xh-75 for qemu-devel@nongnu.org; Thu, 26 Jul 2018 13:23:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fijye-00010I-A7 for qemu-devel@nongnu.org; Thu, 26 Jul 2018 13:23:05 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50760 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fijye-0000zk-49 for qemu-devel@nongnu.org; Thu, 26 Jul 2018 13:23:00 -0400 Date: Thu, 26 Jul 2018 11:22:51 -0600 From: Alex Williamson Message-ID: <20180726112251.2c49b6df@t450s.home> In-Reply-To: <20180726201113-mutt-send-email-mst@kernel.org> References: <1407239306.11199051.1530240887935.JavaMail.zimbra@redhat.com> <20180705194311-mutt-send-email-mst@kernel.org> <20180726145214.GD17777@stefanha-x1.localdomain> <488bdc8d-e36c-ad3e-f7b3-a45a78a99dda@gmail.com> <20180726191315-mutt-send-email-mst@kernel.org> <20180726104252.3d162f34@t450s.home> <20180726201113-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Question: SRIOV support over Win Hyper-V VM running in QEMU process on Linux host List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Stefan Hajnoczi , Tal Attaly , Knut Omang , "qemu-devel@nongnu.org" , Elijah Shakkour On Thu, 26 Jul 2018 20:11:44 +0300 "Michael S. Tsirkin" wrote: > On Thu, Jul 26, 2018 at 10:42:52AM -0600, Alex Williamson wrote: > > On Thu, 26 Jul 2018 19:14:45 +0300 > > "Michael S. Tsirkin" wrote: > > > > > On Thu, Jul 26, 2018 at 06:51:13PM +0300, Marcel Apfelbaum wrote: > > > > Hi > > > > > > > > On 07/26/2018 05:52 PM, Stefan Hajnoczi wrote: > > > > > On Thu, Jul 12, 2018 at 07:33:14AM +0000, Elijah Shakkour wrote: > > > > > > Hey, > > > > > > > > > > > > Our team is adding a NIC functional emulation to QEMU. > > > > > > One of the features we are adding to this NIC is SRIOV. > > > > > > > > > > > > Here is the error message I get when checking SRIOV support of our emulated NIC on Win2016 server (the hyper-v VM). > > > > > > " > > > > > > SR-IOV cannot be used on this system as the PCI Express hardware does not support Access Control Services (ACS) at any root port. > > > > > > > > QEMU's emulated PCI Express Root Ports do not support ACS yet, however I am > > > > not sure ACS is a prerequisite > > > > for SR-IOV. > > > > ACS is certainly not a prerequisite for SR-IOV. > > > > > Looks like windows blocks dev assignment in nested VMs without it. > > > Thinking about it, doesn't vfio do the same by default? I think vfio has > > > a flag to override this though. > > > > IOMMU grouping in Linux takes isolation via ACS and device specific > > mechanisms into account, limiting the granularity with which a > > userspace driver can claim ownership of devices, > > In that you must assign all devices behind this port as a group? Yup. Not very useful with SR-IOV. Thanks, Alex