From patchwork Wed Dec 3 21:40:32 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Konrad Rzeszutek Wilk X-Patchwork-Id: 5433891 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: X-Original-To: patchwork-linux-pci@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 098C09F319 for ; Wed, 3 Dec 2014 21:43:55 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 39C0620265 for ; Wed, 3 Dec 2014 21:43:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5127F201F4 for ; Wed, 3 Dec 2014 21:43:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752603AbaLCVnk (ORCPT ); Wed, 3 Dec 2014 16:43:40 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:33303 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751834AbaLCVlH (ORCPT ); Wed, 3 Dec 2014 16:41:07 -0500 Received: from ucsinet22.oracle.com (ucsinet22.oracle.com [156.151.31.94]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id sB3Lf33P007930 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 3 Dec 2014 21:41:04 GMT Received: from userz7022.oracle.com (userz7022.oracle.com [156.151.31.86]) by ucsinet22.oracle.com (8.14.5+Sun/8.14.5) with ESMTP id sB3Lf27R007523 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 3 Dec 2014 21:41:03 GMT Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userz7022.oracle.com (8.14.5+Sun/8.14.4) with ESMTP id sB3Lf1RO007447; Wed, 3 Dec 2014 21:41:02 GMT Received: from laptop.dumpdata.com (/10.154.99.34) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 03 Dec 2014 13:41:01 -0800 Received: by laptop.dumpdata.com (Postfix, from userid 1000) id 1D96311EEB2; Wed, 3 Dec 2014 16:41:01 -0500 (EST) From: Konrad Rzeszutek Wilk To: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, david.vrabel@citrix.com Cc: Konrad Rzeszutek Wilk Subject: [PATCH v5 7/9] xen/pciback: Restore configuration space when detaching from a guest. Date: Wed, 3 Dec 2014 16:40:32 -0500 Message-Id: <1417642834-20350-8-git-send-email-konrad.wilk@oracle.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1417642834-20350-1-git-send-email-konrad.wilk@oracle.com> References: <1417642834-20350-1-git-send-email-konrad.wilk@oracle.com> X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The commit "xen/pciback: Don't deadlock when unbinding." was using the version of pci_reset_function which would lock the device lock. That is no good as we can dead-lock. As such we swapped to using the lock-less version and requiring that the callers of 'pcistub_put_pci_dev' take the device lock. And as such this bug got exposed. Using the lock-less version is OK, except that we tried to use 'pci_restore_state' after the lock-less version of __pci_reset_function_locked - which won't work as 'state_saved' is set to false. Said 'state_saved' is a toggle boolean that is to be used by the sequence of a) pci_save_state/pci_restore_state or b) pci_load_and_free_saved_state/pci_restore_state. We don't want to use a) as the guest might have messed up the PCI configuration space and we want it to revert to the state when the PCI device was binded to us. Therefore we pick b) to restore the configuration space. We restore from our 'golden' version of PCI configuration space, when an: - Device is unbinded from pciback - Device is detached from a guest. Reported-by: Sander Eikelenboom Signed-off-by: Konrad Rzeszutek Wilk --- v2: Always FLR reset --- drivers/xen/xen-pciback/pci_stub.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c index 843a2ba..8580e53 100644 --- a/drivers/xen/xen-pciback/pci_stub.c +++ b/drivers/xen/xen-pciback/pci_stub.c @@ -105,7 +105,7 @@ static void pcistub_device_release(struct kref *kref) */ __pci_reset_function_locked(dev); if (pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state)) - dev_dbg(&dev->dev, "Could not reload PCI state\n"); + dev_info(&dev->dev, "Could not reload PCI state\n"); else pci_restore_state(dev); @@ -257,6 +257,8 @@ void pcistub_put_pci_dev(struct pci_dev *dev) { struct pcistub_device *psdev, *found_psdev = NULL; unsigned long flags; + struct xen_pcibk_dev_data *dev_data; + int ret; spin_lock_irqsave(&pcistub_devices_lock, flags); @@ -280,8 +282,18 @@ void pcistub_put_pci_dev(struct pci_dev *dev) */ device_lock_assert(&dev->dev); __pci_reset_function_locked(dev); - pci_restore_state(dev); + dev_data = pci_get_drvdata(dev); + ret = pci_load_saved_state(dev, dev_data->pci_saved_state); + if (!ret) { + /* + * The usual sequence is pci_save_state & pci_restore_state + * but the guest might have messed the configuration space up. + * Use the initial version (when device was bound to us). + */ + pci_restore_state(dev); + } else + dev_info(&dev->dev, "Could not reload PCI state\n"); /* This disables the device. */ xen_pcibk_reset_device(dev);