Re: [Qemu-devel] [PATCH 06/13] pci: Add INTx routing notifier

[Jan Kiszka]

On 2012-06-10 11:48, Michael S. Tsirkin wrote:
> On Mon, Jun 04, 2012 at 10:52:14AM +0200, Jan Kiszka wrote:
>> This per-device notifier shall be triggered by any interrupt router
>> along the path of a device's legacy interrupt signal on routing changes.
>> For simplicity reasons and as this is a slow path anyway, no further
>> details on the routing changes are provided. Instead, the callback is
>> expected to use pci_device_get_host_irq to check the effect of the
>> change.
>>
>> Will be used by KVM PCI device assignment and VFIO.
>>
>> Acked-by: Alex Williamson <address@hidden>
>> Signed-off-by: Jan Kiszka <address@hidden>
>> ---
>>  hw/pci.c        |   19 +++++++++++++++++++
>>  hw/pci.h        |    7 +++++++
>>  hw/pci_bridge.c |    8 ++++++++
>>  hw/piix_pci.c   |    2 ++
>>  4 files changed, 36 insertions(+), 0 deletions(-)
>>
>> diff --git a/hw/pci.c b/hw/pci.c
>> index 8878a11..5b99f4b 100644
>> --- a/hw/pci.c
>> +++ b/hw/pci.c
>> @@ -1101,6 +1101,25 @@ PCIINTxRoute pci_device_route_intx_to_irq(PCIDevice 
>> *dev, int pin)
>>      return bus->route_intx_to_irq(bus->irq_opaque, dev->host_intx_pin[pin]);
>>  }
>>  
>> +void pci_bus_fire_intx_routing_notifier(PCIBus *bus)
>> +{
>> +    PCIDevice *dev;
>> +    int i;
>> +
>> +    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
>> +        dev = bus->devices[i];
>> +        if (dev && dev->intx_routing_notifier) {
>> +            dev->intx_routing_notifier(dev);
>> +        }
>> +    }
>> +}
>> +
> 
> No documentation and it's not obvious when do you need
> to do this.

Yes, will add some lines.

> It would seem from the name that it should be called after you change
> interrupt routing at the specific bus?

Correct.

> 
> From commit log it would seem that even irq changes should
> invoke this. So why isn't this notifier at the host bridge then?

Can't follow, where does the commit log imply this? It is only about
routing changes, not IRQ level changes.

> 
>> +void pci_device_set_intx_routing_notifier(PCIDevice *dev,
>> +                                          INTxRoutingNotifier notifier)
>> +{
>> +    dev->intx_routing_notifier = notifier;
>> +}
>> +
> 
> No documentation, and it's not obvious.
> Why is this getting PCIDevice?
> Does this notify users about updates to this device?
> Updates below this device?
> Above this device?

It informs about changes on the route of the device interrupts to the
output of the host bridge.

> 
>>  /***********************************************************/
>>  /* monitor info on PCI */
>>  
>> diff --git a/hw/pci.h b/hw/pci.h
>> index bbba01e..e7237cf 100644
>> --- a/hw/pci.h
>> +++ b/hw/pci.h
>> @@ -182,6 +182,7 @@ typedef struct PCIDeviceClass {
>>      const char *romfile;
>>  } PCIDeviceClass;
>>  
>> +typedef void (*INTxRoutingNotifier)(PCIDevice *dev);
> 
> Let's call it PCIINTx.... please

OK.

> 
>>  typedef int (*MSIVectorUseNotifier)(PCIDevice *dev, unsigned int vector,
>>                                        MSIMessage msg);
>>  typedef void (*MSIVectorReleaseNotifier)(PCIDevice *dev, unsigned int 
>> vector);
>> @@ -261,6 +262,9 @@ struct PCIDevice {
>>      MemoryRegion rom;
>>      uint32_t rom_bar;
>>  
>> +    /* INTx routing notifier */
>> +    INTxRoutingNotifier intx_routing_notifier;
>> +
>>      /* MSI-X notifiers */
>>      MSIVectorUseNotifier msix_vector_use_notifier;
>>      MSIVectorReleaseNotifier msix_vector_release_notifier;
>> @@ -318,6 +322,9 @@ PCIBus *pci_register_bus(DeviceState *parent, const char 
>> *name,
>>                           MemoryRegion *address_space_io,
>>                           uint8_t devfn_min, int nirq);
>>  PCIINTxRoute pci_device_route_intx_to_irq(PCIDevice *dev, int pin);
>> +void pci_bus_fire_intx_routing_notifier(PCIBus *bus);
> 
> Well true it fires the notifier but what it does conceptually
> is update intx routing.

Nope, it informs about updates _after_ they happened.

> 
>> +void pci_device_set_intx_routing_notifier(PCIDevice *dev,
>> +                                          INTxRoutingNotifier notifier);
>>  void pci_device_reset(PCIDevice *dev);
>>  void pci_bus_reset(PCIBus *bus);
>>  
>> diff --git a/hw/pci_bridge.c b/hw/pci_bridge.c
>> index 7d13a85..9ace0b7 100644
>> --- a/hw/pci_bridge.c
>> +++ b/hw/pci_bridge.c
>> @@ -298,6 +298,13 @@ void pci_bridge_reset(DeviceState *qdev)
>>      pci_bridge_reset_reg(dev);
>>  }
>>  
>> +static void pci_bridge_intx_routing_update(PCIDevice *dev)
>> +{
>> +    PCIBridge *br = DO_UPCAST(PCIBridge, dev, dev);
>> +
>> +    pci_bus_fire_intx_routing_notifier(&br->sec_bus);
>> +}
>> +
>>  /* default qdev initialization function for PCI-to-PCI bridge */
>>  int pci_bridge_initfn(PCIDevice *dev)
>>  {
>> @@ -333,6 +340,7 @@ int pci_bridge_initfn(PCIDevice *dev)
>>      sec_bus->address_space_io = &br->address_space_io;
>>      memory_region_init(&br->address_space_io, "pci_bridge_io", 65536);
>>      pci_bridge_region_init(br);
>> +    pci_device_set_intx_routing_notifier(dev, 
>> pci_bridge_intx_routing_update);
>>      QLIST_INIT(&sec_bus->child);
>>      QLIST_INSERT_HEAD(&parent->child, sec_bus, sibling);
>>      return 0;
>> diff --git a/hw/piix_pci.c b/hw/piix_pci.c
>> index 347177f..8fd21f3 100644
>> --- a/hw/piix_pci.c
>> +++ b/hw/piix_pci.c
>> @@ -422,6 +422,8 @@ static void piix3_write_config(PCIDevice *dev,
>>      if (ranges_overlap(address, len, PIIX_PIRQC, 4)) {
>>          PIIX3State *piix3 = DO_UPCAST(PIIX3State, dev, dev);
>>          int pic_irq;
>> +
>> +        pci_bus_fire_intx_routing_notifier(piix3->dev.bus);
>>          piix3_update_irq_levels(piix3);
>>          for (pic_irq = 0; pic_irq < PIIX_NUM_PIC_IRQS; pic_irq++) {
>>              piix3_set_irq_pic(piix3, pic_irq);
>> -- 
>> 1.7.3.4
> 
> 

Thanks,
Jan

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