Re: [PATCH] PCI: Fix pcibios_update_irq misuse of irq number

[Bjorn Helgaas]

On Mon, Feb 2, 2015 at 10:15 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
> On 28/01/15 15:43, Bjorn Helgaas wrote:
>> On Wed, Jan 28, 2015 at 9:27 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
>>> Hi Gerry,
>>>
>>> On 28/01/15 15:21, Jiang Liu wrote:
>>>>
>>>>
>>>> On 2015/1/28 22:51, Marc Zyngier wrote:
>>>>> pcibios_update_irq writes an irq number into the config space
>>>>> of a given PCI device, but ignores the fact that this number
>>>>> is a virtual interrupt number, which might be a very different
>>>>> value from what the underlying hardware is using.
>>>>>
>>>>> The obvious fix is to fetch the HW interrupt number from the
>>>>> corresponding irq_data structure. This is slightly complicated
>>>>> by the fact that this interrupt might be services by a stacked
>>>>> domain.
>>>>>
>>>>> This has been tested on KVM with kvmtool.
>>>>>
>>>>> Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
>>>>> Tested-by: Andre Przywara <andre.przywara@xxxxxxx>
>>>>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>>>>> ---
>>>>>  drivers/pci/setup-irq.c | 12 ++++++++++--
>>>>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c
>>>>> index 4e2d595..828cbc9 100644
>>>>> --- a/drivers/pci/setup-irq.c
>>>>> +++ b/drivers/pci/setup-irq.c
>>>>> @@ -15,11 +15,19 @@
>>>>>  #include <linux/errno.h>
>>>>>  #include <linux/ioport.h>
>>>>>  #include <linux/cache.h>
>>>>> +#include <linux/irq.h>
>>>>>
>>>>>  void __weak pcibios_update_irq(struct pci_dev *dev, int irq)
>>>>>  {
>>>>> -    dev_dbg(&dev->dev, "assigning IRQ %02d\n", irq);
>>>>> -    pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq);
>>>>> +    struct irq_data *d;
>>>>> +
>>>>> +    d = irq_get_irq_data(irq);
>>>>> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>>>>> +    while (d->parent_data)
>>>>> +            d = d->parent_data;
>>>>> +#endif
>>>>> +    dev_dbg(&dev->dev, "assigning IRQ %02ld\n", d->hwirq);
>>>>> +    pci_write_config_byte(dev, PCI_INTERRUPT_LINE, d->hwirq);
>>>>>  }
>>>> Hi Mark,
>>>>       Instead of modifying the common version, how about
>>>> implementing an arch specific version? Arch may have different
>>>> way to determine the irq number. Above implementation doesn't
>>>> work with x86, for example.
>>>
>>> If you look at the Makefile, this file is used on:
>>>
>>> obj-$(CONFIG_ALPHA) += setup-irq.o
>>> obj-$(CONFIG_ARM) += setup-irq.o
>>> obj-$(CONFIG_UNICORE32) += setup-irq.o
>>> obj-$(CONFIG_SUPERH) += setup-irq.o
>>> obj-$(CONFIG_MIPS) += setup-irq.o
>>> obj-$(CONFIG_TILE) += setup-irq.o
>>> obj-$(CONFIG_SPARC_LEON) += setup-irq.o
>>> obj-$(CONFIG_M68K) += setup-irq.o
>>>
>>> x86 doesn't use that at all.
>>
>> Since you're looking at this, Marc, do you see a nice way to get rid
>> of these arch dependencies in the Makefile and unify this a bit?  We
>> still have this pci_fixup_irqs() ugliness -- it's not really
>> arch-specific at all, but it's called from arch code, and it uses
>> for_each_pci_dev(), which obviously only works for things present at
>> boot and not for things hot-added later.
>
> I can have a look at this in the next cycle - I'm a bit strapped for
> time just now.
>
> As for for_each_pci_dev(), I'm not completely clear about what it should
> be replaced for. Do we have some form of notifier for this?

I think this should be done somewhere in the enumeration path, e.g.,
maybe in pci_device_add().  Then we shouldn't need a
for_each_pci_dev() loop or a notifier at all.

Bjorn
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