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Message-ID: <13b939f7-0e63-e81f-ae16-a620a0a765ff@wanyeetech.com>
Date: Mon, 14 Sep 2020 20:06:03 +0800
From: Zhou Yanjie <zhouyanjie@...yeetech.com>
To: Tiezhu Yang <yangtiezhu@...ngson.cn>,
Huacai Chen <chenhuacai@...il.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
linux-pci <linux-pci@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Konstantin Khlebnikov <khlebnikov@...nvz.org>,
Khalid Aziz <khalid.aziz@...cle.com>,
Vivek Goyal <vgoyal@...hat.com>,
Lukas Wunner <lukas@...ner.de>,
Oliver O'Halloran <oohall@...il.com>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
Xuefeng Li <lixuefeng@...ngson.cn>, git <git@...0n.name>,
Huacai Chen <chenhc@...ote.com>
Subject: Re: [RFC PATCH v3] PCI/portdrv: Only disable Bus Master on kexec
reboot and connected PCI devices
Hello Tiezhu
在 2020/9/14 下午7:24, Tiezhu Yang 写道:
> On 09/14/2020 05:46 PM, Huacai Chen wrote:
>> Hi, Tiezhu,
>>
>> On Mon, Sep 14, 2020 at 5:30 PM Tiezhu Yang <yangtiezhu@...ngson.cn>
>> wrote:
>>> On 09/14/2020 04:52 PM, Huacai Chen wrote:
>>>> Hi, Tiezhu,
>>>>
>>>> How do you test kexec? kexec -e or systemctl kexec? Or both?
>>> kexec -l vmlinux --append="root=/dev/sda2 console=ttyS0,115200"
>>> kexec -e
>> So you haven't tested "systemctl kexec"?
>
> Yes, the distro I used is Loongnix which has not kexec service now.
> Is there any problem when use systemctl kexec? If you have more details,
> please let me know.
>
It is inevitable that there will be some omissions during testing. This
is understandable, but what I am more curious about is why you send the
patch that Huacai has already sent every time. Why not strengthen
communication with Huacai and avoid duplication of work?
>>
>> Huacai
>>>> P.S., Please also CC my gmail (chenhuacai@...il.com) since lemote.com
>>>> has some communication problems.
>>> OK, no problem.
>>>
>>>> Huacai
>>>>
>>>>> 陈华才江苏航天龙梦信息技术有限公司/研发中心/软件部 ------------------
>>>>> Original ------------------From: "Tiezhu
>>>>> Yang"<yangtiezhu@...ngson.cn>;Date: Mon, Sep 14, 2020 03:57
>>>>> PMTo: "Bjorn Helgaas"<bhelgaas@...gle.com>; Cc:
>>>>> "linux-pci"<linux-pci@...r.kernel.org>;
>>>>> "linux-kernel"<linux-kernel@...r.kernel.org>; "Rafael J.
>>>>> Wysocki"<rafael.j.wysocki@...el.com>; "Konstantin
>>>>> Khlebnikov"<khlebnikov@...nvz.org>; "Khalid
>>>>> Aziz"<khalid.aziz@...cle.com>; "Vivek Goyal"<vgoyal@...hat.com>;
>>>>> "Lukas Wunner"<lukas@...ner.de>; "Oliver
>>>>> O'Halloran"<oohall@...il.com>; "Huacai Chen"<chenhc@...ote.com>;
>>>>> "Jiaxun Yang"<jiaxun.yang@...goat.com>; "Xuefeng
>>>>> Li"<lixuefeng@...ngson.cn>; Subject: [RFC PATCH v3] 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 when
>>>>> shutdown or reboot.
>>>>>
>>>>> 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 already executed afterwards by the
>>>>> function
>>>>> 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 (drv && drv->shutdown)
>>>>> drv->shutdown(pci_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);
>>>>> }
>>>>>
>>>>> [ 36.159446] Call Trace:
>>>>> [ 36.241688] [<ffffffff80211434>] show_stack+0x9c/0x130
>>>>> [ 36.326619] [<ffffffff80661b70>] dump_stack+0xb0/0xf0
>>>>> [ 36.410403] [<ffffffff806a8240>] pcie_portdrv_shutdown+0x18/0x78
>>>>> [ 36.495302] [<ffffffff8069c6b4>] pci_device_shutdown+0x44/0x90
>>>>> [ 36.580027] [<ffffffff807aac90>] device_shutdown+0x130/0x290
>>>>> [ 36.664486] [<ffffffff80265448>] kernel_power_off+0x38/0x80
>>>>> [ 36.748272] [<ffffffff80265634>] __do_sys_reboot+0x1a4/0x258
>>>>> [ 36.831985] [<ffffffff80218b90>] syscall_common+0x34/0x58
>>>>>
>>>>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>>>>> ---
>>>>> drivers/pci/pcie/portdrv_core.c | 1 -
>>>>> drivers/pci/pcie/portdrv_pci.c | 14 +++++++++++++-
>>>>> 2 files changed, 13 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..cab37a8 100644
>>>>> --- a/drivers/pci/pcie/portdrv_pci.c
>>>>> +++ b/drivers/pci/pcie/portdrv_pci.c
>>>>> @@ -143,6 +143,18 @@ 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);
>>>>> }
>>>>>
>>>>> static pci_ers_result_t pcie_portdrv_error_detected(struct
>>>>> pci_dev *dev,
>>>>> @@ -211,7 +223,7 @@ static struct pci_driver pcie_portdriver = {
>>>>>
>>>>> .probe = pcie_portdrv_probe,
>>>>> .remove = pcie_portdrv_remove,
>>>>> - .shutdown = pcie_portdrv_remove,
>>>>> + .shutdown = pcie_portdrv_shutdown,
>>>>>
>>>>> .err_handler = &pcie_portdrv_err_handler,
>>>>>
>>>>> --
>>>>> 2.1.0
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