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SubjectRE: [PATCH 2/2] Intel-IOMMU, intr-remap: source-id checking
Ingo Molnar wrote:
> * Han, Weidong <weidong.han@intel.com> wrote:
>
>> Ingo Molnar wrote:
>>> * Han, Weidong <weidong.han@intel.com> wrote:
>>>
>>>> Siddha, Suresh B wrote:
>>>>> On Wed, 2009-05-06 at 23:16 -0700, Han, Weidong wrote:
>>>>>> @@ -634,6 +694,44 @@ static int ir_parse_ioapic_scope(struct
>>>>>> acpi_dmar_header *header, " 0x%Lx\n",
>>>>>> scope->enumeration_id, drhd->address);
>>>>>>
>>>>>> + bus = pci_find_bus(drhd->segment, scope->bus);
>>>>>> + path = (struct acpi_dmar_pci_path *)(scope + 1); + count =
>>>>>> (scope->length - + sizeof(struct acpi_dmar_device_scope))
>>>>>> + / sizeof(struct acpi_dmar_pci_path);
>>>>>> +
>>>>>> + while (count) {
>>>>>> + if (pdev)
>>>>>> + pci_dev_put(pdev);
>>>>>> +
>>>>>> + if (!bus)
>>>>>> + break;
>>>>>> +
>>>>>> + pdev = pci_get_slot(bus,
>>>>>> + PCI_DEVFN(path->dev, path->fn));
>>>>>> + if (!pdev)
>>>>>> + break;
>>>>>
>>>>> ir_parse_ioapic_scope() happens very early in the boot. So, I
>>>>> don't think we can do the pci related discovery here.
>>>>>
>>>>
>>>> Thanks for your pointing it out. It should enable the source-id
>>>> checking for io-apic's after the pci subsystem is up. I will
>>>> change it.
>>>
>>> Note, there's ways to do early PCI quirks too, check
>>> arch/x86/kernel/early-quirks.c. It's done by reading the PCI
>>> configuration space directly via a careful early-capable subset of
>>> the PCI config space APIs.
>>>
>>> But it's a method of last resort.
>>>
>>
>> Thanks for your reminder. It can use direct PCI access here as
>> follows. It's easy and clean. I think it's better than adding the
>> source-id checking for io-apic's after the pci subsystem is up. I
>> will send out updated patches after some tests.
>>
>> @@ -634,6 +695,24 @@ static int ir_parse_ioapic_scope(struct
>> acpi_dmar_header *header, " 0x%Lx\n",
>> scope->enumeration_id, drhd->address);
>>
>> + bus = scope->bus;
>> + path = (struct acpi_dmar_pci_path *)(scope +
>> 1); + count = (scope->length -
>> + sizeof(struct
>> acpi_dmar_device_scope)) + /
>> sizeof(struct acpi_dmar_pci_path); + + while
>> (--count > 0) { + /* Access PCI
>> directly due to the PCI + * subsystem
>> isn't initialized yet. + */
>> + bus = read_pci_config_byte(bus,
>> path->dev, + path->fn,
>> PCI_SECONDARY_BUS); + path++;
>> + }
>> +
>> + ir_ioapic[ir_ioapic_num].bus = bus;
>> + ir_ioapic[ir_ioapic_num].devfn =
>> + PCI_DEVFN(path->dev,
>> path->fn);
>
> looks good IMO, beyond the obligatory comment-style nitpick [*] :-)
> Also, the function above seems to be way too large - please split it
> into a couple of natural helper functions.
>
> Thanks,
>
> Ingo
>
> [*]
>
> Please use the customary comment style:
>
> /*
> * Comment .....
> * ...... goes here:
> */
>
> specified in Documentation/CodingStyle.

I have sent out the updated patches. Thanks!

Regards,
Weidong

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