From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06D49C433E1 for ; Wed, 20 May 2020 08:28:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E528F207ED for ; Wed, 20 May 2020 08:28:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726596AbgETI1y (ORCPT ); Wed, 20 May 2020 04:27:54 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:4824 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726832AbgETI1x (ORCPT ); Wed, 20 May 2020 04:27:53 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id C55E4DC67C5329500D04; Wed, 20 May 2020 16:27:45 +0800 (CST) Received: from [10.65.58.147] (10.65.58.147) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Wed, 20 May 2020 16:27:42 +0800 Subject: Re: [PATCH v1 1/1] PCI/ERR: Handle fatal error recovery for non-hotplug capable devices To: , References: <18609.1588812972@famine> CC: , , , From: Yicong Yang Message-ID: Date: Wed, 20 May 2020 16:28:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.65.58.147] X-CFilter-Loop: Reflected Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 2020/5/7 11:32, sathyanarayanan.kuppuswamy@linux.intel.com wrote: > From: Kuppuswamy Sathyanarayanan > > If there are non-hotplug capable devices connected to a given > port, then during the fatal error recovery(triggered by DPC or > AER), after calling reset_link() function, we cannot rely on > hotplug handler to detach and re-enumerate the device drivers > in the affected bus. Instead, we will have to let the error > recovery handler call report_slot_reset() for all devices in > the bus to notify about the reset operation. Although this is > only required for non hot-plug capable devices, doing it for > hotplug capable devices should not affect the functionality. > > Along with above issue, this fix also applicable to following > issue. > > Commit 6d2c89441571 ("PCI/ERR: Update error status after > reset_link()") added support to store status of reset_link() > call. Although this fixed the error recovery issue observed if > the initial value of error status is PCI_ERS_RESULT_DISCONNECT > or PCI_ERS_RESULT_NO_AER_DRIVER, it also discarded the status > result from report_frozen_detected. This can cause a failure to > recover if _NEED_RESET is returned by report_frozen_detected and > report_slot_reset is not invoked. > > Such an event can be induced for testing purposes by reducing the > Max_Payload_Size of a PCIe bridge to less than that of a device > downstream from the bridge, and then initiating I/O through the > device, resulting in oversize transactions. In the presence of DPC, > this results in a containment event and attempted reset and recovery > via pcie_do_recovery. After 6d2c89441571 report_slot_reset is not > invoked, and the device does not recover. > > [original patch is from jay.vosburgh@canonical.com] > [original patch link https://lore.kernel.org/linux-pci/18609.1588812972@famine/] > Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()") > Signed-off-by: Jay Vosburgh > Signed-off-by: Kuppuswamy Sathyanarayanan > --- > drivers/pci/pcie/err.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c > index 14bb8f54723e..db80e1ecb2dc 100644 > --- a/drivers/pci/pcie/err.c > +++ b/drivers/pci/pcie/err.c > @@ -165,13 +165,24 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > pci_dbg(dev, "broadcast error_detected message\n"); > if (state == pci_channel_io_frozen) { > pci_walk_bus(bus, report_frozen_detected, &status); > - status = reset_link(dev); > - if (status != PCI_ERS_RESULT_RECOVERED) { > + status = PCI_ERS_RESULT_NEED_RESET; > + } else { > + pci_walk_bus(bus, report_normal_detected, &status); > + } > + > + if (status == PCI_ERS_RESULT_NEED_RESET) { > + if (reset_link) { > + if (reset_link(dev) != PCI_ERS_RESULT_RECOVERED) we'll call reset_link() only if link is frozen. so it may have problem here. Thanks, Yicong > + status = PCI_ERS_RESULT_DISCONNECT; > + } else { > + if (pci_bus_error_reset(dev)) > + status = PCI_ERS_RESULT_DISCONNECT; > + } > + > + if (status == PCI_ERS_RESULT_DISCONNECT) { > pci_warn(dev, "link reset failed\n"); > goto failed; > } > - } else { > - pci_walk_bus(bus, report_normal_detected, &status); > } > > if (status == PCI_ERS_RESULT_CAN_RECOVER) {