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 41298C83000 for ; Thu, 30 Apr 2020 01:15:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 175B32083B for ; Thu, 30 Apr 2020 01:15:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726309AbgD3BPe (ORCPT ); Wed, 29 Apr 2020 21:15:34 -0400 Received: from mga02.intel.com ([134.134.136.20]:44154 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726284AbgD3BPe (ORCPT ); Wed, 29 Apr 2020 21:15:34 -0400 IronPort-SDR: vwk/ZkgrTLVWsfhR5vSmFcUjbP3TRo8auIXMWLOMXjaGTjgA7dFejBOwzZaQHpltuxbRvEcZGo NP6CQfchQaBQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2020 18:15:33 -0700 IronPort-SDR: Lz6dwKrXX4kXbgy2YxPZXMCWA2X5hHq37SO7ePIAandywsyfhi5wgDT5/7n8HututjPp1qjgYV oX2EKGcWDohQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,333,1583222400"; d="scan'208";a="432765667" Received: from stamimi-mobl2.amr.corp.intel.com (HELO [10.254.111.80]) ([10.254.111.80]) by orsmga005.jf.intel.com with ESMTP; 29 Apr 2020 18:15:33 -0700 Subject: Re: [PATCH] PCI/ERR: Resolve regression in pcie_do_recovery To: Jay Vosburgh , linux-pci@vger.kernel.org Cc: Bjorn Helgaas References: <12115.1588207324@famine> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <18897ceb-2263-1101-ae43-918a66794e14@linux.intel.com> Date: Wed, 29 Apr 2020 18:15:33 -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: <12115.1588207324@famine> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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. > > 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 { >