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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 9ACDCC4724C for ; Thu, 30 Apr 2020 19:35:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8519520656 for ; Thu, 30 Apr 2020 19:35:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726635AbgD3Tfj (ORCPT ); Thu, 30 Apr 2020 15:35:39 -0400 Received: from mga05.intel.com ([192.55.52.43]:35594 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726366AbgD3Tfi (ORCPT ); Thu, 30 Apr 2020 15:35:38 -0400 IronPort-SDR: p7L2+YjXDnEUv31dKqyg5XPYYu15DXRi0DkTS1mm6gCay/GmPqlIg6X+nzXG/G/TFtUKIxdr4c aGMr2+6fK6sw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2020 12:35:38 -0700 IronPort-SDR: hcn3O9GutZeM8fmQeR3busHSjqWFMb2j3W4kxzR9bDk20bg7zfCMtT7yBlAafeCUdqYHJjpd0b Ssaa9eNzwGUg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,336,1583222400"; d="scan'208";a="303368264" Received: from stallamr-mobl1.amr.corp.intel.com (HELO [10.254.73.127]) ([10.254.73.127]) by FMSMGA003.fm.intel.com with ESMTP; 30 Apr 2020 12:35:37 -0700 Subject: Re: [PATCH] PCI/ERR: Resolve regression in pcie_do_recovery From: "Kuppuswamy, Sathyanarayanan" To: Jay Vosburgh , linux-pci@vger.kernel.org Cc: Bjorn Helgaas References: <12115.1588207324@famine> <18897ceb-2263-1101-ae43-918a66794e14@linux.intel.com> Message-ID: Date: Thu, 30 Apr 2020 12:35:37 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <18897ceb-2263-1101-ae43-918a66794e14@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi Jay, On 4/29/20 6:15 PM, Kuppuswamy, Sathyanarayanan wrote: > > > On 4/29/20 5:42 PM, Jay Vosburgh wrote: >>     Commit 6d2c89441571 ("PCI/ERR: Update error status after >> reset_link()"), introduced a regression, as pcie_do_recovery will >> discard 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 initating 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. > > I think this issue is related to the issue discussed in following > thread (DPC non-hotplug support). > > https://lkml.org/lkml/2020/3/28/328 > > If my assumption is correct, you are dealing with devices which are > not hotplug capable. If the devices are hotplug capable then you don't > need to proceed to report_slot_reset(), since hotplug handler will > remove/re-enumerate the devices correctly. Can you check whether following fix works for you? This includes support for bus_reset in recovery function itself. index 14bb8f54723e..c9eaab68ab7a 100644 --- a/drivers/pci/pcie/err.c +++ b/drivers/pci/pcie/err.c @@ -165,13 +165,23 @@ 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) { 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) + 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) { > >> >>     Inspection shows a similar path is plausible for a return of >> _CAN_RECOVER and the invocation of report_mmio_enabled. >> >>     Resolve this by preserving the result of report_frozen_detected if >> reset_link does not return _DISCONNECT. >> >> Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()") >> Signed-off-by: Jay Vosburgh >> >> --- >>   drivers/pci/pcie/err.c | 11 +++++++++-- >>   1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c >> index 14bb8f54723e..e4274562f3a0 100644 >> --- a/drivers/pci/pcie/err.c >> +++ b/drivers/pci/pcie/err.c >> @@ -164,10 +164,17 @@ 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_ers_result_t status2; >> + >>           pci_walk_bus(bus, report_frozen_detected, &status); >> -        status = reset_link(dev); >> -        if (status != PCI_ERS_RESULT_RECOVERED) { >> +        /* preserve status from report_frozen_detected to >> +         * insure report_mmio_enabled or report_slot_reset are >> +         * invoked even if reset_link returns _RECOVERED. >> +         */ >> +        status2 = reset_link(dev); >> +        if (status2 != PCI_ERS_RESULT_RECOVERED) { >>               pci_warn(dev, "link reset failed\n"); >> +            status = status2; >>               goto failed; >>           } >>       } else { >>