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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 B4330C433E2 for ; Mon, 14 Sep 2020 06:17:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7286520756 for ; Mon, 14 Sep 2020 06:17:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726051AbgINGRn (ORCPT ); Mon, 14 Sep 2020 02:17:43 -0400 Received: from mail.loongson.cn ([114.242.206.163]:48156 "EHLO loongson.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726003AbgINGRe (ORCPT ); Mon, 14 Sep 2020 02:17:34 -0400 Received: from [10.130.0.155] (unknown [113.200.148.30]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9DxX8fsCl9fdx4VAA--.5787S3; Mon, 14 Sep 2020 14:17:17 +0800 (CST) Subject: Re: [RFC PATCH v2] PCI/portdrv: Only disable Bus Master on kexec reboot and connected PCI devices To: Huacai Chen , Bjorn Helgaas References: <1600028950-10644-1-git-send-email-yangtiezhu@loongson.cn> Cc: Konstantin Khlebnikov , Khalid Aziz , Vivek Goyal , Lukas Wunner , oohall , "rafael.j.wysocki" , Xuefeng Li , Jiaxun Yang , linux-pci , linux-kernel , zhouyanjie , git From: Tiezhu Yang Message-ID: <939d35d9-bbe7-3fef-7fc6-ff331d8f5010@loongson.cn> Date: Mon, 14 Sep 2020 14:17:15 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID: AQAAf9DxX8fsCl9fdx4VAA--.5787S3 X-Coremail-Antispam: 1UD129KBjvJXoW3Ary3tr18tw1rZr4UAw4DCFg_yoW7Xw47pF ZxJa92yFWFqry2gr4avFyUuFy5XwsFy348Kry8G343Wr42yryktFWxtFyY9a4kZrZYgF17 JF98Jr97GFyUJF7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUB014x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AKxV W0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv 7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY6r 1j6r4UM4x0Y48IcVAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628v n2kIc2xKxwCYjI0SjxkI62AI1cAE67vIY487MxkIecxEwVAFwVW8AwCF04k20xvY0x0EwI xGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480 Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7 IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k2 6cxKx2IYs7xG6Fyj6rWUJwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I 0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUnc_TUUUUU X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/14/2020 12:31 PM, Huacai Chen wrote: > Hi, Tiezhu > >> ------------------ Original ------------------ >> From: "Tiezhu Yang"; >> Date: Mon, Sep 14, 2020 04:29 AM >> To: "Bjorn Helgaas"; >> Cc: "Konstantin Khlebnikov"; "Khalid Aziz"; "Vivek Goyal"; "Lukas Wunner"; "oohall"; "rafael.j.wysocki"; "Xuefeng Li"; "Huacai Chen"; "Jiaxun Yang"; "linux-pci"; "linux-kernel"; >> Subject: [RFC PATCH v2] PCI/portdrv: Only disable Bus Master on kexec reboot and connected PCI devices >> >> >> >> After commit 745be2e700cd ("PCIe: portdrv: call pci_disable_device >> during remove") and commit cc27b735ad3a ("PCI/portdrv: Turn off PCIe >> services during shutdown"), it also calls pci_disable_device() during >> shutdown, this leads to shutdown or reboot failure occasionally due to >> clear PCI_COMMAND_MASTER on the device in do_pci_disable_device(). >> >> drivers/pci/pci.c >> static void do_pci_disable_device(struct pci_dev *dev) >> { >> u16 pci_command; >> >> pci_read_config_word(dev, PCI_COMMAND, &pci_command); >> if (pci_command & PCI_COMMAND_MASTER) { >> pci_command &= ~PCI_COMMAND_MASTER; >> pci_write_config_word(dev, PCI_COMMAND, pci_command); >> } >> >> pcibios_disable_device(dev); >> } >> >> When remove "pci_command &= ~PCI_COMMAND_MASTER;", it can work well. >> >> As Oliver O'Halloran said, no need to call pci_disable_device() when >> actually shutting down, but we should call pci_disable_device() before >> handing over to the new kernel on kexec reboot, so we can do some >> condition checks which are similar with pci_device_shutdown(), this is >> done by commit 4fc9bbf98fd6 ("PCI: Disable Bus Master only on kexec >> reboot") and commit 6e0eda3c3898 ("PCI: Don't try to disable Bus Master >> on disconnected PCI devices"). >> >> drivers/pci/pci-driver.c >> static void pci_device_shutdown(struct device *dev) >> { >> ... >> >> /* >> * If this is a kexec reboot, turn off Bus Master bit on the >> * device to tell it to not continue to do DMA. Don't touch >> * devices in D3cold or unknown states. >> * If it is not a kexec reboot, firmware will hit the PCI >> * devices with big hammer and stop their DMA any way. >> */ >> if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot)) >> pci_clear_master(pci_dev); >> } > Have you really tried kexec? Why do you think kexec can disable pci > device successfully while normal reboot/poweroff cannot? Yes, I test it on kexec reboot, it works well. > > Huacai >> Signed-off-by: Tiezhu Yang >> --- >> drivers/pci/pcie/portdrv_core.c | 1 - >> drivers/pci/pcie/portdrv_pci.c | 25 ++++++++++++++++++++++++- >> 2 files changed, 24 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c >> index 50a9522..1991aca 100644 >> --- a/drivers/pci/pcie/portdrv_core.c >> +++ b/drivers/pci/pcie/portdrv_core.c >> @@ -491,7 +491,6 @@ void pcie_port_device_remove(struct pci_dev *dev) >> { >> device_for_each_child(&dev->dev, NULL, remove_iter); >> pci_free_irq_vectors(dev); >> - pci_disable_device(dev); >> } >> >> /** >> diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c >> index 3a3ce40..ce89a9e8 100644 >> --- a/drivers/pci/pcie/portdrv_pci.c >> +++ b/drivers/pci/pcie/portdrv_pci.c >> @@ -15,6 +15,7 @@ >> #include >> #include >> #include >> +#include >> >> #include "../pci.h" >> #include "portdrv.h" >> @@ -143,6 +144,28 @@ static void pcie_portdrv_remove(struct pci_dev *dev) >> } >> >> pcie_port_device_remove(dev); >> + pci_disable_device(dev); >> +} >> + >> +static void pcie_portdrv_shutdown(struct pci_dev *dev) >> +{ >> + if (pci_bridge_d3_possible(dev)) { >> + pm_runtime_forbid(&dev->dev); >> + pm_runtime_get_noresume(&dev->dev); >> + pm_runtime_dont_use_autosuspend(&dev->dev); >> + } >> + >> + pcie_port_device_remove(dev); >> + >> + /* >> + * If this is a kexec reboot, turn off Bus Master bit on the >> + * device to tell it to not continue to do DMA. Don't touch >> + * devices in D3cold or unknown states. >> + * If it is not a kexec reboot, firmware will hit the PCI >> + * devices with big hammer and stop their DMA any way. >> + */ >> + if (kexec_in_progress && (dev->current_state <= PCI_D3hot)) >> + pci_disable_device(dev); >> } >> >> static pci_ers_result_t pcie_portdrv_error_detected(struct pci_dev *dev, >> @@ -211,7 +234,7 @@ static void pcie_portdrv_err_resume(struct pci_dev *dev) >> >> .probe = pcie_portdrv_probe, >> .remove = pcie_portdrv_remove, >> - .shutdown = pcie_portdrv_remove, >> + .shutdown = pcie_portdrv_shutdown, >> >> .err_handler = &pcie_portdrv_err_handler, >> >> -- >> 1.8.3.1