From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751716AbcIIGOd (ORCPT ); Fri, 9 Sep 2016 02:14:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:59620 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750841AbcIIGOb (ORCPT ); Fri, 9 Sep 2016 02:14:31 -0400 Subject: Re: [PATCH v2] xen/pciback: support driver_override To: Boris Ostrovsky , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org References: <1472819456-12995-1-git-send-email-jgross@suse.com> <74aef1d8-8f92-f7e4-fc40-a13708a2bf19@oracle.com> Cc: david.vrabel@citrix.com From: Juergen Gross X-Enigmail-Draft-Status: N1110 Message-ID: <69161c4e-02ac-5b02-8c9a-161d2ec2d6ce@suse.com> Date: Fri, 9 Sep 2016 08:14:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2 MIME-Version: 1.0 In-Reply-To: <74aef1d8-8f92-f7e4-fc40-a13708a2bf19@oracle.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/09/16 16:10, Boris Ostrovsky wrote: > On 09/02/2016 08:30 AM, Juergen Gross wrote: >> Support the driver_override scheme introduced with commit 782a985d7af2 >> ("PCI: Introduce new device binding path using pci_dev.driver_override") >> >> As pcistub_probe() is called for all devices (it has to check for a >> match based on the slot address rather than device type) it has to >> check for driver_override set to "pciback" itself. >> >> Signed-off-by: Juergen Gross >> --- >> V2: removed now unused label >> --- >> drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++------ >> 1 file changed, 10 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c >> index 258b7c3..85c28f7 100644 >> --- a/drivers/xen/xen-pciback/pci_stub.c >> +++ b/drivers/xen/xen-pciback/pci_stub.c >> @@ -25,6 +25,8 @@ >> #include "conf_space.h" >> #include "conf_space_quirks.h" >> >> +#define PCISTUB_DRIVER_NAME "pciback" >> + >> static char *pci_devs_to_hide; >> wait_queue_head_t xen_pcibk_aer_wait_queue; >> /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops, >> @@ -529,16 +531,18 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id) >> "don't have a normal (0) or bridge (1) " >> "header type!\n"); >> err = -ENODEV; >> - goto out; >> } >> >> + } else if (!dev->driver_override || >> + strcmp(dev->driver_override, PCISTUB_DRIVER_NAME)) >> + /* Didn't find the device */ >> + err = -ENODEV; >> + >> + if (!err) { >> dev_info(&dev->dev, "seizing device\n"); >> err = pcistub_seize(dev); >> - } else >> - /* Didn't find the device */ >> - err = -ENODEV; >> + } > > Should devices with pciback override be displayed in > /sys/bus/pci/drivers/pciback/slots? If they should then they need to be > either added to pcistub_device_ids or kept on some other list. No, I don't think so. The patch is just needed to _avoid_ having to use the slots stuff: without the patch you need something like: echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind echo 0000:07:10.0 > /sys/bus/pci/drivers/pciback/new_slot echo 0000:07:10.0 > /sys/bus/pci/drivers_probe while with the patch you can use the same mechanism as for similar drivers like pci-stub and vfio-pci: echo pciback > /sys/bus/pci/devices/0000\:07\:10.0/driver_override echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind echo 0000:07:10.0 > /sys/bus/pci/drivers_probe So e.g. libvirt doesn't need special handling for pciback. The slot list is necessary for assigning devices to pciback on boot, but I think the override mechanism is better for runtime assignment. > Also, do you think checking override might better be done first, before > testing for ID match? Why? I don't think this really matters. Juergen