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

From: [email-masked] (Jiang Liu)
Date: Tue, 03 Feb 2015 00:06:43 +0800

On 2015/2/2 23:57, Bjorn Helgaas wrote:
> On Wed, Jan 28, 2015 at 8:51 AM, Marc Zyngier <[email-masked]> 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 <[email-masked]>
>> Tested-by: Andre Przywara <[email-masked]>
>> Signed-off-by: Marc Zyngier <[email-masked]>
> 
> Jiang, are you OK with this patch as-is now, since it isn't used on x86?
Sure, I'm OK. I missed the point that it's not used on x86 at all
in previous review.

> 
> Marc, Lorenzo, I assume this actually fixes a bug.  Can we get any
> more details about what happens when you hit the bug, and how you
> reproduced it (what platform, driver, etc.)?
> 
> Bjorn
> 
>> ---
>>  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);
>>  }
>>
>>  static void pdev_fixup_irq(struct pci_dev *dev,
>> --
>> 2.1.4
>>