Re: [Qemu-devel] [PATCH] kvm: add KVM_IRQFD_FLAG_RESAMPLE support

[Vincenzo Maffione]

Actually our research group (at University of Pisa) is working on some
paravirtualization extensions of the e1000 NIC emulation that needs
KVM_IRQFD_FLAG_RESAMPLE support. This is one of the reasons why I'm
proposing this patch.

Do you suggest modifying vfio_enable_intx_kvm() to take advantage of
the patch? I haven't addressed vfio only because I wasn't sure I am
"permitted" to do that.


Thanks,
  Vincenzo

2013/7/22 Alex Williamson <address@hidden>:
>
> On Mon, 2013-07-22 at 12:43 +0200, Vincenzo Maffione wrote:
>> From e59e35380380c2986cd0164f11dcd8a07a8e4e59 Mon Sep 17 00:00:00 2001
>> From: Vincenzo Maffione <address@hidden>
>> Date: Mon, 22 Jul 2013 11:51:33 +0200
>> Subject: [PATCH] kvm: add KVM_IRQFD_FLAG_RESAMPLE support
>>
>> Added an EventNotifier* parameter to
>> kvm-all.c:kvm_irqchip_add_irqfd_notifier(), in order to give KVM
>> another eventfd to be used as "resamplefd". See the documentation
>> in the linux kernel sources in Documentation/virtual/kvm/api.txt
>> (section 4.75) for more details.
>> When the added parameter is passed NULL, the behaviour of the
>> function is unchanged with respect to the previous versions.
>>
>> Signed-off-by: Vincenzo Maffione <address@hidden>
>> ---
>>  hw/misc/vfio.c         |  4 ++--
>>  hw/virtio/virtio-pci.c |  2 +-
>>  include/sysemu/kvm.h   |  3 ++-
>>  kvm-all.c              | 17 +++++++++++++----
>>  4 files changed, 18 insertions(+), 8 deletions(-)
>>
>> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
>> index ad8ce77..54af34a 100644
>> --- a/hw/misc/vfio.c
>> +++ b/hw/misc/vfio.c
>> @@ -646,7 +646,7 @@ static int vfio_msix_vector_do_use(PCIDevice
>> *pdev, unsigned int nr,
>>      vector->virq = msg ? kvm_irqchip_add_msi_route(kvm_state, *msg) : -1;
>>      if (vector->virq < 0 ||
>>          kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
>> -                                       vector->virq) < 0) {
>> +                                       NULL, vector->virq) < 0) {
>>          if (vector->virq >= 0) {
>>              kvm_irqchip_release_virq(kvm_state, vector->virq);
>>              vector->virq = -1;
>> @@ -814,7 +814,7 @@ retry:
>>          vector->virq = kvm_irqchip_add_msi_route(kvm_state, msg);
>>          if (vector->virq < 0 ||
>>              kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
>> -                                           vector->virq) < 0) {
>> +                                           NULL, vector->virq) < 0) {
>>              qemu_set_fd_handler(event_notifier_get_fd(&vector->interrupt),
>>                                  vfio_msi_interrupt, NULL, vector);
>>          }
>
>
> Why doesn't this address the only current user of
> KVM_IRQFD_FLAG_RESAMPLE, vfio_enable_intx_kvm()?  Thanks,
>
> Alex
>
>
>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>> index c38cfd1..c4db407 100644
>> --- a/hw/virtio/virtio-pci.c
>> +++ b/hw/virtio/virtio-pci.c
>> @@ -508,7 +508,7 @@ static int kvm_virtio_pci_irqfd_use(VirtIOPCIProxy 
>> *proxy,
>>      VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no);
>>      EventNotifier *n = virtio_queue_get_guest_notifier(vq);
>>      int ret;
>> -    ret = kvm_irqchip_add_irqfd_notifier(kvm_state, n, irqfd->virq);
>> +    ret = kvm_irqchip_add_irqfd_notifier(kvm_state, n, NULL, irqfd->virq);
>>      return ret;
>>  }
>>
>> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
>> index 1e08a85..9e5d78e 100644
>> --- a/include/sysemu/kvm.h
>> +++ b/include/sysemu/kvm.h
>> @@ -309,7 +309,8 @@ int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage 
>> msg);
>>  int kvm_irqchip_update_msi_route(KVMState *s, int virq, MSIMessage msg);
>>  void kvm_irqchip_release_virq(KVMState *s, int virq);
>>
>> -int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n, int virq);
>> +int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n,
>> +                                   EventNotifier *rn, int virq);
>>  int kvm_irqchip_remove_irqfd_notifier(KVMState *s, EventNotifier *n, int 
>> virq);
>>  void kvm_pc_gsi_handler(void *opaque, int n, int level);
>>  void kvm_pc_setup_irq_routing(bool pci_enabled);
>> diff --git a/kvm-all.c b/kvm-all.c
>> index 232c39a..3f69b41 100644
>> --- a/kvm-all.c
>> +++ b/kvm-all.c
>> @@ -1230,7 +1230,8 @@ int kvm_irqchip_update_msi_route(KVMState *s,
>> int virq, MSIMessage msg)
>>      return kvm_update_routing_entry(s, &kroute);
>>  }
>>
>> -static int kvm_irqchip_assign_irqfd(KVMState *s, int fd, int virq, bool 
>> assign)
>> +static int kvm_irqchip_assign_irqfd(KVMState *s, int fd, int rfd, int virq,
>> +                                    bool assign)
>>  {
>>      struct kvm_irqfd irqfd = {
>>          .fd = fd,
>> @@ -1238,6 +1239,11 @@ static int kvm_irqchip_assign_irqfd(KVMState
>> *s, int fd, int virq, bool assign)
>>          .flags = assign ? 0 : KVM_IRQFD_FLAG_DEASSIGN,
>>      };
>>
>> +    if (rfd != -1) {
>> +        irqfd.flags |= KVM_IRQFD_FLAG_RESAMPLE;
>> +        irqfd.resamplefd = rfd;
>> +    }
>> +
>>      if (!kvm_irqfds_enabled()) {
>>          return -ENOSYS;
>>      }
>> @@ -1276,14 +1282,17 @@ int kvm_irqchip_update_msi_route(KVMState *s,
>> int virq, MSIMessage msg)
>>  }
>>  #endif /* !KVM_CAP_IRQ_ROUTING */
>>
>> -int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n, int virq)
>> +int kvm_irqchip_add_irqfd_notifier(KVMState *s, EventNotifier *n,
>> +                                   EventNotifier *rn, int virq)
>>  {
>> -    return kvm_irqchip_assign_irqfd(s, event_notifier_get_fd(n), virq, 
>> true);
>> +    return kvm_irqchip_assign_irqfd(s, event_notifier_get_fd(n),
>> +           rn ? event_notifier_get_fd(rn) : -1, virq, true);
>>  }
>>
>>  int kvm_irqchip_remove_irqfd_notifier(KVMState *s, EventNotifier *n, int 
>> virq)
>>  {
>> -    return kvm_irqchip_assign_irqfd(s, event_notifier_get_fd(n), virq, 
>> false);
>> +    return kvm_irqchip_assign_irqfd(s, event_notifier_get_fd(n), -1, virq,
>> +           false);
>>  }
>>
>>  static int kvm_irqchip_create(KVMState *s)
>> --
>> 1.8.3.3
>
>
>
>



-- 
Vincenzo Maffione