From patchwork Sat Jan 9 01:00:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kuppuswamy Sathyanarayanan X-Patchwork-Id: 1424018 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DCMDn06Tbz9sWK for ; Sat, 9 Jan 2021 12:04:09 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726500AbhAIBDm (ORCPT ); Fri, 8 Jan 2021 20:03:42 -0500 Received: from mga11.intel.com ([192.55.52.93]:37225 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726437AbhAIBDm (ORCPT ); Fri, 8 Jan 2021 20:03:42 -0500 IronPort-SDR: Z86BNDsmh8gF7BcZBLfQj5dmoo+mrRxcep3BeuIAhgGmGSj6glc7BXSTDblZffx1D0HfkafdKR ToIKXFG0UiHQ== X-IronPort-AV: E=McAfee;i="6000,8403,9858"; a="174166648" X-IronPort-AV: E=Sophos;i="5.79,333,1602572400"; d="scan'208";a="174166648" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2021 17:00:35 -0800 IronPort-SDR: WgQdquRfqtT+wqOwODsdiHhPmbqEN0sAm51wYn/DertKoetWAyqjtLPaGbr1K58rLrfjrMvjHL FPMgk+ukhecw== X-IronPort-AV: E=Sophos;i="5.79,333,1602572400"; d="scan'208";a="423126453" Received: from tanmingy-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.212.247.214]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2021 17:00:24 -0800 From: Kuppuswamy Sathyanarayanan To: bhelgaas@google.com Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, knsathya@kernel.org Subject: [PATCH v9 2/2] PCI/ERR: Split the fatal and non-fatal error recovery handling Date: Fri, 8 Jan 2021 17:00:01 -0800 Message-Id: <6f63321637fef86b6cf0beebf98b987062f9e811.1610153755.git.sathyanarayanan.kuppuswamy@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") merged fatal and non-fatal error recovery paths, and also made recovery code depend on hotplug handler for "remove affected device + rescan" support. But this change also complicated the error recovery path and which in turn led to the following issues. 1. We depend on hotplug handler for removing the affected devices/drivers on DLLSC LINK down event (on DPC event trigger) and DPC handler for handling the error recovery. Since both handlers operate on same set of affected devices, it leads to race condition, which in turn leads to  NULL pointer exceptions or error recovery failures.You can find more details about this issue in following link. https://lore.kernel.org/linux-pci/20201007113158.48933-1-haifeng.zhao@intel.com/T/#t 2. For non-hotplug capable devices fatal (DPC) error recovery is currently broken. Current fatal error recovery implementation relies on PCIe hotplug (pciehp) handler for detaching and re-enumerating the affected devices/drivers. So when dealing with non-hotplug capable devices, recovery code does not restore the state of the affected devices correctly. You can find more details about this issue in the following links. https://lore.kernel.org/linux-pci/20200527083130.4137-1-Zhiqiang.Hou@nxp.com/ https://lore.kernel.org/linux-pci/12115.1588207324@famine/ https://lore.kernel.org/linux-pci/0e6f89cd6b9e4a72293cc90fafe93487d7c2d295.1585000084.git.sathyanarayanan.kuppuswamy@linux.intel.com/ In order to fix the above two issues, we should stop relying on hotplug handler for cleaning the affected devices/drivers and let error recovery handler own this functionality. So this patch reverts Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") and re-introduce the  "remove affected device + rescan"  functionality in fatal error recovery handler. Also holding pci_lock_rescan_remove() will prevent the race between hotplug and DPC handler. Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") Signed-off-by: Kuppuswamy Sathyanarayanan Reviewed-by: Sinan Kaya --- Changes since v8: * Rebased on top of v5.11-rc1. Changes since v7: * Rebased on top of v5.10-rc1. Changes since v6: * Renamed pcie_do_nonfatal_recovery() to pcie_nonfatal_recovery(). * Renamed pcie_do_fatal_recovery() to pcie_fatal_recovery(). * Addressed some format issues. Changes since v5: * Fixed static/non-static declartion issue. Changes since v4: * Added new interfaces for error recovery (pcie_do_fatal_recovery() and pcie_do_nonfatal_recovery()). Documentation/PCI/pci-error-recovery.rst | 47 +++++++++++------ Documentation/PCI/pcieaer-howto.rst | 2 +- drivers/pci/pci.h | 7 +-- drivers/pci/pcie/aer.c | 10 ++-- drivers/pci/pcie/dpc.c | 2 +- drivers/pci/pcie/edr.c | 2 +- drivers/pci/pcie/err.c | 67 +++++++++++++++++------- 7 files changed, 91 insertions(+), 46 deletions(-) diff --git a/Documentation/PCI/pci-error-recovery.rst b/Documentation/PCI/pci-error-recovery.rst index 84ceebb08cac..830c8af5838b 100644 --- a/Documentation/PCI/pci-error-recovery.rst +++ b/Documentation/PCI/pci-error-recovery.rst @@ -115,7 +115,7 @@ The actual steps taken by a platform to recover from a PCI error event will be platform-dependent, but will follow the general sequence described below. -STEP 0: Error Event +STEP 0: Error Event: ERR_NONFATAL ------------------- A PCI bus error is detected by the PCI hardware. On powerpc, the slot is isolated, in that all I/O is blocked: all reads return 0xffffffff, @@ -160,10 +160,10 @@ particular, if the platform doesn't isolate slots), and recovery proceeds to STEP 2 (MMIO Enable). If any driver requested a slot reset (by returning PCI_ERS_RESULT_NEED_RESET), -then recovery proceeds to STEP 4 (Slot Reset). +then recovery proceeds to STEP 3 (Slot Reset). If the platform is unable to recover the slot, the next step -is STEP 6 (Permanent Failure). +is STEP 5 (Permanent Failure). .. note:: @@ -198,7 +198,7 @@ reset or some such, but not restart operations. This callback is made if all drivers on a segment agree that they can try to recover and if no automatic link reset was performed by the HW. If the platform can't just re-enable IOs without a slot reset or a link reset, it will not call this callback, and -instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset) +instead will have gone directly to STEP 3 (Slot Reset) .. note:: @@ -233,18 +233,12 @@ The driver should return one of the following result codes: The next step taken depends on the results returned by the drivers. If all drivers returned PCI_ERS_RESULT_RECOVERED, then the platform -proceeds to either STEP3 (Link Reset) or to STEP 5 (Resume Operations). +proceeds to STEP 4 (Resume Operations). If any driver returned PCI_ERS_RESULT_NEED_RESET, then the platform -proceeds to STEP 4 (Slot Reset) +proceeds to STEP 3 (Slot Reset) -STEP 3: Link Reset ------------------- -The platform resets the link. This is a PCI-Express specific step -and is done whenever a fatal error has been detected that can be -"solved" by resetting the link. - -STEP 4: Slot Reset +STEP 3: Slot Reset ------------------ In response to a return value of PCI_ERS_RESULT_NEED_RESET, the @@ -322,7 +316,7 @@ PCI card types:: + pdev->needs_freset = 1; + -Platform proceeds either to STEP 5 (Resume Operations) or STEP 6 (Permanent +Platform proceeds either to STEP 4 (Resume Operations) or STEP 5 (Permanent Failure). .. note:: @@ -332,7 +326,7 @@ Failure). However, it probably should. -STEP 5: Resume Operations +STEP 4: Resume Operations ------------------------- The platform will call the resume() callback on all affected device drivers if all drivers on the segment have returned @@ -344,7 +338,7 @@ a result code. At this point, if a new error happens, the platform will restart a new error recovery sequence. -STEP 6: Permanent Failure +STEP 5: Permanent Failure ------------------------- A "permanent failure" has occurred, and the platform cannot recover the device. The platform will call error_detected() with a @@ -367,6 +361,27 @@ errors. See the discussion in powerpc/eeh-pci-error-recovery.txt for additional detail on real-life experience of the causes of software errors. +STEP 0: Error Event: ERR_FATAL +-------------------- +PCI bus error is detected by the PCI hardware. On powerpc, the slot is +isolated, in that all I/O is blocked: all reads return 0xffffffff, all +writes are ignored. + +STEP 1: Remove devices +--------------------- +Platform removes the devices depending on the error agent, it could be +this port for all subordinates or upstream component (likely downstream +port) + +STEP 2: Reset link +--------------------- +The platform resets the link. This is a PCI-Express specific step and is +done whenever a fatal error has been detected that can be "solved" by +resetting the link. + +STEP 3: Re-enumerate the devices +--------------------- +Initiates the re-enumeration. Conclusion; General Remarks --------------------------- diff --git a/Documentation/PCI/pcieaer-howto.rst b/Documentation/PCI/pcieaer-howto.rst index 0b36b9ebfa4b..d6376cfc8920 100644 --- a/Documentation/PCI/pcieaer-howto.rst +++ b/Documentation/PCI/pcieaer-howto.rst @@ -206,7 +206,7 @@ error_detected(dev, pci_channel_io_frozen) to all drivers within a hierarchy in question. Then, performing link reset at upstream is necessary. As different kinds of devices might use different approaches to reset link, AER port service driver is required to provide the -function to reset link via callback parameter of pcie_do_recovery() +function to reset link via callback parameter of pcie_fatal_recovery() function. If reset_link is not NULL, recovery function will use it to reset the link. If error_detected returns PCI_ERS_RESULT_CAN_RECOVER and reset_link returns PCI_ERS_RESULT_RECOVERED, the error handling goes diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 5c59365092fa..1134d599222c 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -572,9 +572,10 @@ static inline int pci_dev_specific_disable_acs_redir(struct pci_dev *dev) #endif /* PCI error reporting and recovery */ -pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, - pci_channel_state_t state, - pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev)); +pci_ers_result_t pcie_nonfatal_recovery(struct pci_dev *dev); + +pci_ers_result_t pcie_fatal_recovery(struct pci_dev *dev, + pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev)); bool pcie_wait_for_link(struct pci_dev *pdev, bool active); #ifdef CONFIG_PCIEASPM diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c index 77b0f2c45bc0..5a8a79826fd6 100644 --- a/drivers/pci/pcie/aer.c +++ b/drivers/pci/pcie/aer.c @@ -952,9 +952,9 @@ static void handle_error_source(struct pci_dev *dev, struct aer_err_info *info) if (pcie_aer_is_native(dev)) pcie_clear_device_status(dev); } else if (info->severity == AER_NONFATAL) - pcie_do_recovery(dev, pci_channel_io_normal, aer_root_reset); + pcie_nonfatal_recovery(dev); else if (info->severity == AER_FATAL) - pcie_do_recovery(dev, pci_channel_io_frozen, aer_root_reset); + pcie_fatal_recovery(dev, aer_root_reset); pci_dev_put(dev); } @@ -990,11 +990,9 @@ static void aer_recover_work_func(struct work_struct *work) } cper_print_aer(pdev, entry.severity, entry.regs); if (entry.severity == AER_NONFATAL) - pcie_do_recovery(pdev, pci_channel_io_normal, - aer_root_reset); + pcie_nonfatal_recovery(pdev); else if (entry.severity == AER_FATAL) - pcie_do_recovery(pdev, pci_channel_io_frozen, - aer_root_reset); + pcie_fatal_recovery(pdev, aer_root_reset); pci_dev_put(pdev); } } diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c index e05aba86a317..d2c8917c0729 100644 --- a/drivers/pci/pcie/dpc.c +++ b/drivers/pci/pcie/dpc.c @@ -236,7 +236,7 @@ static irqreturn_t dpc_handler(int irq, void *context) dpc_process_error(pdev); /* We configure DPC so it only triggers on ERR_FATAL */ - pcie_do_recovery(pdev, pci_channel_io_frozen, dpc_reset_link); + pcie_fatal_recovery(pdev, dpc_reset_link); return IRQ_HANDLED; } diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c index a6b9b479b97a..86218ada8fb9 100644 --- a/drivers/pci/pcie/edr.c +++ b/drivers/pci/pcie/edr.c @@ -183,7 +183,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data) * or ERR_NONFATAL, since the link is already down, use the FATAL * error recovery path for both cases. */ - estate = pcie_do_recovery(edev, pci_channel_io_frozen, dpc_reset_link); + estate = pcie_fatal_recovery(edev, dpc_reset_link); send_ost: diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c index 6c19e9948232..79f4c0003585 100644 --- a/drivers/pci/pcie/err.c +++ b/drivers/pci/pcie/err.c @@ -79,11 +79,6 @@ static int report_error_detected(struct pci_dev *dev, return 0; } -static int report_frozen_detected(struct pci_dev *dev, void *data) -{ - return report_error_detected(dev, pci_channel_io_frozen, data); -} - static int report_normal_detected(struct pci_dev *dev, void *data) { return report_error_detected(dev, pci_channel_io_normal, data); @@ -169,14 +164,59 @@ static void pci_walk_bridge(struct pci_dev *bridge, cb(bridge, userdata); } -pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, - pci_channel_state_t state, +pci_ers_result_t pcie_fatal_recovery(struct pci_dev *dev, pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev)) { int type = pci_pcie_type(dev); - struct pci_dev *bridge; + struct pci_host_bridge *host = pci_find_host_bridge(dev->bus); + struct pci_dev *bridge, *pdev, *temp; + struct pci_bus *bus; + pci_ers_result_t result; + + if (type == PCI_EXP_TYPE_ROOT_PORT || + type == PCI_EXP_TYPE_DOWNSTREAM || + type == PCI_EXP_TYPE_RC_EC || + type == PCI_EXP_TYPE_RC_END) + bridge = dev; + else + bridge = pci_upstream_bridge(dev); + + bus = bridge->subordinate; + pci_walk_bridge(bridge, pci_dev_set_disconnected, NULL); + + pci_lock_rescan_remove(); + pci_dev_get(dev); + list_for_each_entry_safe_reverse(pdev, temp, &bus->devices, bus_list) { + pci_stop_and_remove_bus_device(pdev); + } + + result = reset_subordinates(bridge); + + pci_aer_clear_fatal_status(dev); + if (host->native_aer || pcie_ports_native) + pcie_clear_device_status(dev); + + if (result == PCI_ERS_RESULT_RECOVERED) { + if (pcie_wait_for_link(bridge, true)) + pci_rescan_bus(bridge->bus); + pci_info(bridge, "Device recovery from fatal error successful\n"); + } else { + pci_uevent_ers(bridge, PCI_ERS_RESULT_DISCONNECT); + pci_info(bridge, "Device recovery from fatal error failed\n"); + } + + pci_dev_put(dev); + pci_unlock_rescan_remove(); + + return result; +} + +pci_ers_result_t pcie_nonfatal_recovery(struct pci_dev *dev) +{ + int type = pci_pcie_type(dev); pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER; struct pci_host_bridge *host = pci_find_host_bridge(dev->bus); + struct pci_dev *bridge; int ret; /* @@ -197,16 +237,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, bridge = pci_upstream_bridge(dev); pci_dbg(bridge, "broadcast error_detected message\n"); - if (state == pci_channel_io_frozen) { - pci_walk_bridge(bridge, report_frozen_detected, &status); - status = reset_subordinates(bridge); - if (status != PCI_ERS_RESULT_RECOVERED) { - pci_warn(bridge, "subordinate device reset failed\n"); - goto failed; - } - } else { - pci_walk_bridge(bridge, report_normal_detected, &status); - } + pci_walk_bridge(bridge, report_normal_detected, &status); if (status == PCI_ERS_RESULT_CAN_RECOVER) { status = PCI_ERS_RESULT_RECOVERED;