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

[Paolo Bonzini <pbonzini@redhat.com>]

Il 22/07/2013 16:18, Vincenzo Maffione ha scritto:
> 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.

If you have a patch to do that, I guess it's welcome. :)

Otherwise, this patch makes sense from the point of view of supporting
the KVM API in a more complete manner.

Paolo

> 
> 
> Thanks,
>   Vincenzo
> 
> 2013/7/22 Alex Williamson <alex.williamson@redhat.com>:
>>
>> On Mon, 2013-07-22 at 12:43 +0200, Vincenzo Maffione wrote:
>>> From e59e35380380c2986cd0164f11dcd8a07a8e4e59 Mon Sep 17 00:00:00 2001
>>> From: Vincenzo Maffione <v.maffione@gmail.com>
>>> 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 <v.maffione@gmail.com>
>>> ---
>>>  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
>>
>>
>>
>>
> 
> 
>