Re: [Qemu-devel] [PATCH 1/2] kvm irqfd: support msimessage to irq translation in PHB

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 08/19/2013 05:35 PM, Michael S. Tsirkin wrote:
> On Wed, Aug 07, 2013 at 06:51:32PM +1000, Alexey Kardashevskiy wrote:
>> On PPC64 systems MSI Messages are translated to system IRQ in a PCI
>> host bridge. This is already supported for emulated MSI/MSIX but
>> not for irqfd where the current QEMU allocates IRQ numbers from
>> irqchip and maps MSIMessages to those IRQ in the host kernel.
>>
>> The patch extends irqfd support in order to avoid unnecessary
>> mapping and reuse the one which already exists in a PCI host bridge.
>>
>> Specifically, a map_msi callback is added to PCIBus and pci_bus_map_msi()
>> to PCI API. The latter tries a bus specific map_msi and falls back to
>> the default kvm_irqchip_add_msi_route() if none set.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> The mapping (irq # within data) is really KVM on PPC64 specific,
> isn't it?
> 
> So why not implement
> kvm_irqchip_add_msi_route(kvm_state, msg);
> to simply return msg.data on PPC64?

How exactly? Please give some details. kvm_irqchip_add_msi_route() is
implemented in kvm-all.c once for all platforms so hack it right there?

I thought we discussed all of this already and decided that this thing
should go to PCI host bridge and by default PHB's map_msi() callback should
just call kvm_irqchip_add_msi_route(). This is why I touched i386.

Things have changed since then?



> Then you won't have to change all the rest of the code.
> 
>> ---
>> Changes:
>> 2013/08/07 v5:
>> * pci_bus_map_msi now has default behaviour which is to call
>> kvm_irqchip_add_msi_route
>> * kvm_irqchip_release_virq fixed not crash when there is no routes
>> ---
>>  hw/i386/kvm/pci-assign.c | 4 ++--
>>  hw/misc/vfio.c           | 4 ++--
>>  hw/pci/pci.c             | 9 +++++++++
>>  hw/virtio/virtio-pci.c   | 2 +-
>>  include/hw/pci/pci.h     | 2 ++
>>  include/hw/pci/pci_bus.h | 1 +
>>  kvm-all.c                | 3 +++
>>  7 files changed, 20 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/i386/kvm/pci-assign.c b/hw/i386/kvm/pci-assign.c
>> index 5618173..fb59982 100644
>> --- a/hw/i386/kvm/pci-assign.c
>> +++ b/hw/i386/kvm/pci-assign.c
>> @@ -1008,9 +1008,9 @@ static void assigned_dev_update_msi(PCIDevice *pci_dev)
>>          MSIMessage msg = msi_get_message(pci_dev, 0);
>>          int virq;
>>  
>> -        virq = kvm_irqchip_add_msi_route(kvm_state, msg);
>> +        virq = pci_bus_map_msi(kvm_state, pci_dev->bus, msg);
>>          if (virq < 0) {
>> -            perror("assigned_dev_update_msi: kvm_irqchip_add_msi_route");
>> +            perror("assigned_dev_update_msi: pci_bus_map_msi");
>>              return;
>>          }
>>
> 
> This really confuses me. Why are you changing i386 code?
> 
>   
>> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
>> index 017e693..adcd23d 100644
>> --- a/hw/misc/vfio.c
>> +++ b/hw/misc/vfio.c
>> @@ -643,7 +643,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr,
>>       * Attempt to enable route through KVM irqchip,
>>       * default to userspace handling if unavailable.
>>       */
>> -    vector->virq = msg ? kvm_irqchip_add_msi_route(kvm_state, *msg) : -1;
>> +    vector->virq = msg ? pci_bus_map_msi(kvm_state, vdev->pdev.bus, *msg) : -1;
>>      if (vector->virq < 0 ||
>>          kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
>>                                         vector->virq) < 0) {
>> @@ -811,7 +811,7 @@ retry:
>>           * Attempt to enable route through KVM irqchip,
>>           * default to userspace handling if unavailable.
>>           */
>> -        vector->virq = kvm_irqchip_add_msi_route(kvm_state, msg);
>> +        vector->virq = pci_bus_map_msi(kvm_state, vdev->pdev.bus, msg);
>>          if (vector->virq < 0 ||
>>              kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
>>                                             vector->virq) < 0) {
>> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
>> index 4c004f5..4bce3e7 100644
>> --- a/hw/pci/pci.c
>> +++ b/hw/pci/pci.c
>> @@ -1249,6 +1249,15 @@ void pci_device_set_intx_routing_notifier(PCIDevice *dev,
>>      dev->intx_routing_notifier = notifier;
>>  }
>>  
>> +int pci_bus_map_msi(KVMState *s, PCIBus *bus, MSIMessage msg)
>> +{
>> +    if (bus->map_msi) {
>> +        return bus->map_msi(s, bus, msg);
>> +    }
>> +
>> +    return kvm_irqchip_add_msi_route(s, msg);
>> +}
>> +
>>  /*
>>   * PCI-to-PCI bridge specification
>>   * 9.1: Interrupt routing. Table 9-1
>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>> index d37037e..21180d2 100644
>> --- a/hw/virtio/virtio-pci.c
>> +++ b/hw/virtio/virtio-pci.c
>> @@ -481,7 +481,7 @@ static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
>>      int ret;
>>  
>>      if (irqfd->users == 0) {
>> -        ret = kvm_irqchip_add_msi_route(kvm_state, msg);
>> +        ret = pci_bus_map_msi(kvm_state, proxy->pci_dev.bus, msg);
>>          if (ret < 0) {
>>              return ret;
>>          }
>> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
>> index ccec2ba..b6ad9e4 100644
>> --- a/include/hw/pci/pci.h
>> +++ b/include/hw/pci/pci.h
>> @@ -332,6 +332,7 @@ MemoryRegion *pci_address_space_io(PCIDevice *dev);
>>  typedef void (*pci_set_irq_fn)(void *opaque, int irq_num, int level);
>>  typedef int (*pci_map_irq_fn)(PCIDevice *pci_dev, int irq_num);
>>  typedef PCIINTxRoute (*pci_route_irq_fn)(void *opaque, int pin);
>> +typedef int (*pci_map_msi_fn)(KVMState *s, PCIBus *bus, MSIMessage msg);
>>  
>>  typedef enum {
>>      PCI_HOTPLUG_DISABLED,
>> @@ -375,6 +376,7 @@ bool pci_intx_route_changed(PCIINTxRoute *old, PCIINTxRoute *new);
>>  void pci_bus_fire_intx_routing_notifier(PCIBus *bus);
>>  void pci_device_set_intx_routing_notifier(PCIDevice *dev,
>>                                            PCIINTxRoutingNotifier notifier);
>> +int pci_bus_map_msi(KVMState *s, PCIBus *bus, MSIMessage msg);
>>  void pci_device_reset(PCIDevice *dev);
>>  void pci_bus_reset(PCIBus *bus);
>>  
>> diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
>> index 9df1788..5bf7994 100644
>> --- a/include/hw/pci/pci_bus.h
>> +++ b/include/hw/pci/pci_bus.h
>> @@ -16,6 +16,7 @@ struct PCIBus {
>>      pci_set_irq_fn set_irq;
>>      pci_map_irq_fn map_irq;
>>      pci_route_irq_fn route_intx_to_irq;
>> +    pci_map_msi_fn map_msi;
>>      pci_hotplug_fn hotplug;
>>      DeviceState *hotplug_qdev;
>>      void *irq_opaque;
>> diff --git a/kvm-all.c b/kvm-all.c
>> index 716860f..3ae5274 100644
>> --- a/kvm-all.c
>> +++ b/kvm-all.c
>> @@ -1069,6 +1069,9 @@ void kvm_irqchip_release_virq(KVMState *s, int virq)
>>      struct kvm_irq_routing_entry *e;
>>      int i;
>>  
>> +    if (!s->irq_routes) {
>> +        return;
>> +    }
>>      for (i = 0; i < s->irq_routes->nr; i++) {
>>          e = &s->irq_routes->entries[i];
>>          if (e->gsi == virq) {
>> -- 
>> 1.8.3.2


-- 
Alexey