Re: [PATCH v5 6/6] virtio-pci: add support for configure interrupt

[Cindy Lu]

On Fri, Apr 9, 2021 at 3:39 PM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2021/4/8 下午5:38, Cindy Lu 写道:
> > Add support for configure interrupt, use kvm_irqfd_assign and set the
> > gsi to kernel. When the configure notifier was eventfd_signal by host
> > kernel, this will finally inject an msix interrupt to guest
> >
> > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > ---
> >   hw/virtio/virtio-pci.c | 91 ++++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 88 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index 481f6e7505..7b02f42c06 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -664,7 +664,6 @@ static uint32_t virtio_read_config(PCIDevice *pci_dev,
> >   }
> >
> >   static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
> > -                                        unsigned int queue_no,
> >                                           unsigned int vector)
> >   {
> >       VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
> > @@ -726,7 +725,7 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy 
> > *proxy, int nvqs)
> >           if (vector >= msix_nr_vectors_allocated(dev)) {
> >               continue;
> >           }
> > -        ret = kvm_virtio_pci_vq_vector_use(proxy, queue_no, vector);
> > +        ret = kvm_virtio_pci_vq_vector_use(proxy,  vector);
> >           if (ret < 0) {
> >               goto undo;
> >           }
> > @@ -760,6 +759,56 @@ undo:
> >       }
> >       return ret;
> >   }
> > +static int kvm_virtio_pci_vector_config_use(VirtIOPCIProxy *proxy)
> > +{
> > +    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> > +    unsigned int vector;
> > +    int ret;
> > +    EventNotifier *n = virtio_get_config_notifier(vdev);
> > +    vector = vdev->config_vector ;
> > +    ret = kvm_virtio_pci_vq_vector_use(proxy, vector);
> > +    if (ret < 0) {
> > +        goto undo;
> > +    }
> > +    ret = kvm_virtio_pci_irqfd_use(proxy,  n, vector);
>
>
> So the kvm_virtio_pci_vector_use() has the following codes:
>
>          /* If guest supports masking, set up irqfd now.
>           * Otherwise, delay until unmasked in the frontend.
>           */
>          if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
>              vq = virtio_get_queue(vdev, queue_no);
>              n = virtio_queue_get_guest_notifier(vq);
>              ret = kvm_virtio_pci_irqfd_use(proxy, n, vector);
>              if (ret < 0) {
>                  kvm_virtio_pci_vq_vector_release(proxy, vector);
>                  goto undo;
>              }
>          }
>
> Do we need to check the masking support here as well?
>
> Btw, I think we can factor out the core logic (decouple the queue_no) of
> kvm_virtio_pci_vector_user() and let it be reused by config interrupt.
>
sure , I will rewrite this part
>
> > +    if (ret < 0) {
> > +        goto undo;
> > +    }
> > +    return 0;
> > +undo:
> > +    kvm_virtio_pci_irqfd_release(proxy, n, vector);
> > +    return ret;
> > +}
> > +static void kvm_virtio_pci_vector_config_release(VirtIOPCIProxy *proxy)
> > +{
> > +    PCIDevice *dev = &proxy->pci_dev;
> > +    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> > +    unsigned int vector;
> > +    EventNotifier *n = virtio_get_config_notifier(vdev);
> > +    vector = vdev->config_vector ;
> > +    if (vector >= msix_nr_vectors_allocated(dev)) {
> > +        return;
> > +    }
> > +    kvm_virtio_pci_irqfd_release(proxy, n, vector);
> > +    kvm_virtio_pci_vq_vector_release(proxy, vector);
> > +}
> > +static int virtio_pci_set_config_notifier(DeviceState *d,  bool assign)
> > +{
> > +    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
> > +    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> > +    EventNotifier *notifier = virtio_get_config_notifier(vdev);
> > +    int r = 0;
> > +    if (assign) {
> > +        r = event_notifier_init(notifier, 0);
> > +        virtio_set_config_notifier_fd_handler(vdev, true, true);
> > +        kvm_virtio_pci_vector_config_use(proxy);
> > +    } else {
> > +        virtio_set_config_notifier_fd_handler(vdev, false, true);
>
>
> So let's try to unify the codes between this and
> virtio_queue_set_guest_notifier_fd_handler(). Bascailly it's just
> decouple virtqueue *.
>
sure will fix this
>
> > +        kvm_virtio_pci_vector_config_release(proxy);
> > +        event_notifier_cleanup(notifier);
> > +    }
> > +    return r;
> > +}
> >
> >   static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
> >   {
> > @@ -858,6 +907,14 @@ static int virtio_pci_vector_unmask(PCIDevice *dev, 
> > unsigned vector,
> >       EventNotifier *n;
> >       int ret, index, unmasked = 0;
> >
> > +   if (vdev->use_config_notifier == true) {
> > +        n = virtio_get_config_notifier(vdev);
> > +        ret = virtio_pci_vq_vector_unmask(proxy, 0, vector, msg,
> > +                    VIRTIO_CONFIG_VECTOR, n);
> > +        if (ret < 0) {
> > +            goto config_undo;
> > +       }
> > +    }
> >       while (vq) {
> >           index = virtio_get_queue_index(vq);
> >           if (!virtio_queue_get_num(vdev, index)) {
> > @@ -889,6 +946,10 @@ undo:
> >           }
> >           vq = virtio_vector_next_queue(vq);
> >       }
> > + config_undo:
> > +            n = virtio_get_config_notifier(vdev);
> > +            virtio_pci_vq_vector_mask(proxy, 0, vector,
> > +                VIRTIO_CONFIG_VECTOR, n);
> >       return ret;
> >   }
> >
> > @@ -900,6 +961,10 @@ static void virtio_pci_vector_mask(PCIDevice *dev, 
> > unsigned vector)
> >       EventNotifier *n;
> >       int index;
> >
> > +   if (vdev->use_config_notifier == true) {
>
>
> Is this sufficient to know the vector is used by config interrupt?
>
>
> > +        n = virtio_get_config_notifier(vdev);
> > +        virtio_pci_vq_vector_mask(proxy, 0, vector, VIRTIO_CONFIG_VECTOR, 
> > n);
> > +   }
> >       while (vq) {
> >           index = virtio_get_queue_index(vq);
> >            n = virtio_queue_get_guest_notifier(vq);
> > @@ -945,6 +1010,21 @@ static void virtio_pci_vector_poll(PCIDevice *dev,
> >               msix_set_pending(dev, vector);
> >           }
> >       }
> > +   if (vdev->use_config_notifier == true) {
> > +        vector = vdev->config_vector;
> > +        notifier = virtio_get_config_notifier(vdev);
> > +        if (vector < vector_start || vector >= vector_end ||
> > +            !msix_is_masked(dev, vector)) {
> > +            return;
> > +        }
> > +        if (k->guest_notifier_pending) {
> > +            if (k->guest_notifier_pending(vdev, 0,  VIRTIO_CONFIG_VECTOR)) 
> > {
> > +                msix_set_pending(dev, vector);
> > +            }
> > +        } else if (event_notifier_test_and_clear(notifier)) {
> > +            msix_set_pending(dev, vector);
> > +        }
> > +    }
>
>
> Let's unify the code here with the code that deal with vq vectors in the
> loop above.
>
> Thanks
>
>
> >   }
> >
> >   static int virtio_pci_set_guest_notifier(DeviceState *d, int n, bool 
> > assign,
> > @@ -1032,6 +1112,10 @@ static int 
> > virtio_pci_set_guest_notifiers(DeviceState *d, int nvqs, bool assign)
> >                   goto assign_error;
> >               }
> >           }
> > +            r = virtio_pci_set_config_notifier(d, assign);
> > +            if (r < 0) {
> > +                goto config_error;
> > +         }
> >           r = msix_set_vector_notifiers(&proxy->pci_dev,
> >                                         virtio_pci_vector_unmask,
> >                                         virtio_pci_vector_mask,
> > @@ -1048,7 +1132,8 @@ notifiers_error:
> >           assert(assign);
> >           kvm_virtio_pci_vector_release(proxy, nvqs);
> >       }
> > -
> > + config_error:
> > +        kvm_virtio_pci_vector_config_release(proxy);
> >   assign_error:
> >       /* We get here on assignment failure. Recover by undoing for VQs 0 .. 
> > n. */
> >       assert(assign);
>