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

[Jason Wang]

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.


> +    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 *.


> +        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);