From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anirban Chakraborty Subject: Re: xl/SR-IOV: disposition of VFs when PF disappears? Date: Mon, 27 Oct 2014 17:53:01 +0000 Message-ID: References: <544E4A4E020000780004267D@mail.emea.novell.com> <1414414666.23883.13.camel@eu.citrix.com> <20141027133534.GC4050@laptop.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XioTa-00038w-5i for xen-devel@lists.xenproject.org; Mon, 27 Oct 2014 17:53:06 +0000 In-Reply-To: <20141027133534.GC4050@laptop.dumpdata.com> Content-Language: en-US Content-ID: <41AE79705998C7438BD189904A44CC98@namprd05.prod.outlook.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk , Ian Campbell Cc: Wei Liu , Stefano Stabellini , "ian.jackson@eu.citrix.com" , Jan Beulich , xen-devel List-Id: xen-devel@lists.xenproject.org On 10/27/14, 6:35 AM, "Konrad Rzeszutek Wilk" wrote: >On Mon, Oct 27, 2014 at 12:57:46PM +0000, Ian Campbell wrote: >> On Mon, 2014-10-27 at 12:36 +0000, Jan Beulich wrote: >> > All, >> > >> > Intel reports that the sequence >> > >> > - xl pci-assignable-add >> > - briefly run guest using that device [not sure whether that's really >>a >> > necessary step] >> > - xl pci-assignable-add >> > >> > results in both VF and PF being listed as assignable (the fact that >>as a >> > result the PF handed to a guest doesn't work is secondary here, as I >> > think this is a driver issue). Is that really how it should be? >>Shouldn't >> > instead all VFs get removed when the PF device (e.g. due to the >> > PF driver getting unloaded, which is a necessary part of making it >> > assignable) goes away? Or is it required for the admin to manually >> > remove the assignable VFs prior to making the PF go away? > >I am not sure I see the problem. If the user wishes to give the PF and >VF to a guest they should be able to do so? Theoretically, yes a guest can have a PF and all its VFs. However, from security perspective PF having the privilege of resetting the device etc., should stay in a privileged domain. Most of the NICs have some sort of PF-VF communication where the PF driver would ensure that VF drivers are notified of imminent PF removal so that the VF drivers can prepare for a graceful halt of IO. Ideally, a PF removal should do a hot unplug of the VFs from the guests and admin should not have to manually remove them. Anirban > >> >> xl is just controlling/exposing the set of devices which are bound to >> pciback here. (pci-assignable-list is literally a readdir loop over the >> relevant sysfs dir). >> >> I'm not sure if it should be up to (lib)xl, pciback or the core Linux >> pci stuff to handle the creation/destruction of VF devices when the PF >> driver is unbound/assigned. In fact I'm not even sure if VF lifetime is >> in any way tied to the PF driver state. > >It is. When we detect that the device is a VF we set some flag so that the >PF won't try to de-allocate the VFs. > >> >> I've added Konrad for a kernel-size pciback perspective. >> >> Ian. >> > >_______________________________________________ >Xen-devel mailing list >Xen-devel@lists.xen.org >http://lists.xen.org/xen-devel