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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 17E39C4724C for ; Thu, 30 Apr 2020 20:41:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EEEBB206C0 for ; Thu, 30 Apr 2020 20:41:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726784AbgD3Uln convert rfc822-to-8bit (ORCPT ); Thu, 30 Apr 2020 16:41:43 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:60299 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727995AbgD3Ulm (ORCPT ); Thu, 30 Apr 2020 16:41:42 -0400 Received: from 1.general.jvosburgh.us.vpn ([10.172.68.206] helo=famine.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jUG03-0005x7-DF; Thu, 30 Apr 2020 20:41:39 +0000 Received: by famine.localdomain (Postfix, from userid 1000) id B0CD8630E4; Thu, 30 Apr 2020 13:41:37 -0700 (PDT) Received: from famine (localhost [127.0.0.1]) by famine.localdomain (Postfix) with ESMTP id A612DAC1DB; Thu, 30 Apr 2020 13:41:37 -0700 (PDT) From: Jay Vosburgh To: "Kuppuswamy\, Sathyanarayanan" cc: linux-pci@vger.kernel.org, Bjorn Helgaas Subject: Re: [PATCH] PCI/ERR: Resolve regression in pcie_do_recovery In-reply-to: References: <12115.1588207324@famine> <18897ceb-2263-1101-ae43-918a66794e14@linux.intel.com> Comments: In-reply-to "Kuppuswamy, Sathyanarayanan" message dated "Thu, 30 Apr 2020 12:35:37 -0700." X-Mailer: MH-E 8.6+git; nmh 1.6; GNU Emacs 27.0.50 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Date: Thu, 30 Apr 2020 13:41:37 -0700 Message-ID: <14682.1588279297@famine> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org "Kuppuswamy, Sathyanarayanan" wrote: >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. Correct, this particular device (a network card) is in a non-hotplug slot. >Can you check whether following fix works for you? Yes, it does. I fixed up the whitespace and made a minor change to add braces in what look like the correct places around the "if (reset_link)" block; the patch I tested with is below. I'll also install this on another machine with hotplug capable slots to test there as well. 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) + 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) { -J >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 { >>> --- -Jay Vosburgh, jay.vosburgh@canonical.com