Date:	Tue, 19 Jan 2016 17:02:03 +0100
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Sinan Kaya <okaya@...eaurora.org>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Chen Fan <chen.fan.fnst@...fujitsu.com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Len Brown <lenb@...nel.org>, izumi.taku@...fujitsu.com,
	wency@...fujitsu.com, caoj.fnst@...fujitsu.com,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Linux PCI <linux-pci@...r.kernel.org>
Subject: Re: [PATCH] pci: fix unavailable irq number 255 reported by BIOS

On Tue, Jan 19, 2016 at 4:51 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
> On 1/19/2016 10:39 AM, Rafael J. Wysocki wrote:
>> On Tue, Jan 19, 2016 at 3:48 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
>>> On 1/19/2016 9:20 AM, Rafael J. Wysocki wrote:
>>>> On Tuesday, January 19, 2016 02:43:30 PM Rafael J. Wysocki wrote:
>>>>> On Tuesday, January 19, 2016 09:45:13 AM Chen Fan wrote:
>>>>>> In our environment, when enable Secure boot, we found an abnormal
>>>>>> phenomenon as following call trace shows. after investigation, we
>>>>>> found the firmware assigned an irq number 255 which means unknown
>>>>>> or no connection in PCI local spec for i801_smbus, meanwhile the
>>>>>> ACPI didn't configure the pci irq routing. and the 255 irq number
>>>>>> was assigned for megasa msix without IRQF_SHARED. then in this case
>>>>>> during i801_smbus probe, the i801_smbus driver would request irq with
>>>>>> bad irq number 255. but the 255 irq number was assigned for memgasa
>>>>>> with MSIX enable. which will cause request_irq fails, and call trace
>>>>>> shows, actually, we should expose the error early, rather than in request
>>>>>> irq, here we simply fix the problem by return err when find the irq is
>>>>>> 255.
>>>>>>
>>>>>> See the call trace:
>>>>>>
>>>>>>  [   32.459195] ipmi device interface
>>>>>>  [   32.612907] shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
>>>>>>  [   32.800459] ixgbe: Intel(R) 10 Gigabit PCI Express Network Driver - version 4.0.1-k-rh
>>>>>>  [   32.818319] ixgbe: Copyright (c) 1999-2014 Intel Corporation.
>>>>>>  [   32.844009] lpc_ich 0001:80:1f.0: I/O space for ACPI uninitialized
>>>>>>  [   32.850093] i801_smbus 0000:00:1f.3: enabling device (0140 -> 0143)
>>>>>>  [   32.851134] i801_smbus 0000:00:1f.3: can't derive routing for PCI INT C
>>>>>>  [   32.851136] i801_smbus 0000:00:1f.3: PCI INT C: no GSI
>>>>>>  [   32.851164] genirq: Flags mismatch irq 255. 00000080 (i801_smbus) vs. 00000000 (megasa
>>>>>>  [   32.851168] CPU: 0 PID: 2487 Comm: kworker/0:1 Not tainted 3.10.0-229.el7.x86_64 #1
>>>>>>  [   32.851170] Hardware name: FUJITSU PRIMEQUEST 2800E2/D3736, BIOS PRIMEQUEST 2000 Serie5
>>>>>>  [   32.851178] Workqueue: events work_for_cpu_fn
>>>>>>  [   32.851208]  ffff88086c330b00 00000000e233a9df ffff88086d57bca0 ffffffff81603f36
>>>>>>  [   32.851227]  ffff88086d57bcf8 ffffffff8110d23a ffff88686fe02000 0000000000000246
>>>>>>  [   32.851246]  ffff88086a9a8c00 00000000e233a9df ffffffffa00ad220 0000000000000080
>>>>>>  [   32.851247] Call Trace:
>>>>>>  [   32.851261]  [<ffffffff81603f36>] dump_stack+0x19/0x1b
>>>>>>  [   32.851271]  [<ffffffff8110d23a>] __setup_irq+0x54a/0x570
>>>>>>  [   32.851282]  [<ffffffffa00ad220>] ? i801_check_pre.isra.5+0xe0/0xe0 [i2c_i801]
>>>>>>  [   32.851289]  [<ffffffff8110d3bc>] request_threaded_irq+0xcc/0x170
>>>>>>  [   32.851298]  [<ffffffffa00ae87f>] i801_probe+0x32f/0x508 [i2c_i801]
>>>>>>  [   32.851308]  [<ffffffff81308385>] local_pci_probe+0x45/0xa0
>>>>>>  [   32.851315]  [<ffffffff8108bfd4>] work_for_cpu_fn+0x14/0x20
>>>>>>  [   32.851323]  [<ffffffff8108f0ab>] process_one_work+0x17b/0x470
>>>>>>  [   32.851330]  [<ffffffff81090003>] worker_thread+0x293/0x400
>>>>>>  [   32.851338]  [<ffffffff8108fd70>] ? rescuer_thread+0x400/0x400
>>>>>>  [   32.851346]  [<ffffffff8109726f>] kthread+0xcf/0xe0
>>>>>>  [   32.851353]  [<ffffffff810971a0>] ? kthread_create_on_node+0x140/0x140
>>>>>>  [   32.851362]  [<ffffffff81613cfc>] ret_from_fork+0x7c/0xb0
>>>>>>  [   32.851369]  [<ffffffff810971a0>] ? kthread_create_on_node+0x140/0x140
>>>>>>  [   32.851373] i801_smbus 0000:00:1f.3: Failed to allocate irq 255: -16
>>>>>>  [   32.851435] i801_smbus: probe of 0000:00:1f.3 failed with error -16
>>>>>>  [   33.180145] ixgbe 0000:5a:00.0: Multiq[   33.240538] ixgbe 0000:5a:00.0: (PCI Express:03:e0
>>>>>>  [   33.280826] ixgbe 0000:5a:00.0: MAC: 3, PHY: 0, PBA No: 000000-000
>>>>>>
>>>>>> Signed-off-by: Chen Fan <chen.fan.fnst@...fujitsu.com>
>>>>>> ---
>>>>>>  drivers/acpi/pci_irq.c | 10 +++++++++-
>>>>>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
>>>>>> index d30184c..d2f47f8 100644
>>>>>> --- a/drivers/acpi/pci_irq.c
>>>>>> +++ b/drivers/acpi/pci_irq.c
>>>>>> @@ -439,9 +439,17 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
>>>>>>             if (acpi_isa_register_gsi(dev))
>>>>>>                     dev_warn(&dev->dev, "PCI INT %c: no GSI\n",
>>>>>>                              pin_name(pin));
>>>>>> +           rc = 0;
>>>>>> +           /*
>>>>>> +            * Excluding the BIOS report the value 255, which meaning
>>>>>> +            * "unknown" or "no connection" in PCI Local Bus Specification
>>>>>> +            * Revision 3.0 February 3, 2004, P223.
>>>>>
>>>>> You mean the footnote on page 223 talking about the Interrupt Line values, right?
>>>
>>> "Unknown" does not necessarily mean invalid. I have a platform that is using 255 as a valid legacy
>>> interrupt on PCI Express.
>>
>> So first off this is about the Interrupt Line value not about an
>> interrupt vector.
>
> Got it. Just to be clear, I assume this is not the value that code reads from the ACPI table.
>
> +               rc = dev->irq == 0xff ? -EINVAL : 0;
>
> I was nervous to see this check in common code.

No, this value is read from the PCI register, but the interpretation
of it is arch-specific according to the spec.

Thanks,
Rafael

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