Re: [PATCH v8 7/9] virtio-pci: decouple notifier from interrupt process

[Jason Wang <jasowang@redhat.com>]

在 2021/7/6 下午3:20, Cindy Lu 写道:
> use the virtio_pci_get_notifier function to
> get the notifer, the input of the function
> will is the idx, the output is notifier and
> vector


You need to describe why such decoupling is needed.


>
> Signed-off-by: Cindy Lu <lulu@redhat.com>


I think we need move this patch as patch 3.


> ---
>   hw/virtio/virtio-pci.c | 45 ++++++++++++++++++++++++++++++++----------
>   1 file changed, 35 insertions(+), 10 deletions(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 2fe5b1f5aa..fe06847b62 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -710,6 +710,28 @@ static void kvm_virtio_pci_irqfd_release(VirtIOPCIProxy *proxy,
>       ret = kvm_irqchip_remove_irqfd_notifier_gsi(kvm_state, n, irqfd->virq);
>       assert(ret == 0);
>   }
> +static int virtio_pci_get_notifier(VirtIOPCIProxy *proxy, int queue_no,
> +                                      EventNotifier **n, unsigned int *vector)
> +{
> +    PCIDevice *dev = &proxy->pci_dev;
> +    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> +    VirtQueue *vq;
> +
> +    if (queue_no == VIRTIO_CONFIG_IRQ_IDX) {
> +        return -1;
> +    } else {
> +        if (!virtio_queue_get_num(vdev, queue_no)) {
> +            return -1;
> +        }
> +        *vector = virtio_queue_vector(vdev, queue_no);
> +        vq = virtio_get_queue(vdev, queue_no);
> +        *n = virtio_queue_get_guest_notifier(vq);
> +    }
> +    if (*vector >= msix_nr_vectors_allocated(dev)) {
> +        return -1;
> +    }
> +    return 0;
> +}
>   
>   static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
>   {
> @@ -718,13 +740,15 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
>       VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>       unsigned int vector;
>       int ret, queue_no;
> -    VirtQueue *vq;
>       EventNotifier *n;
>       for (queue_no = 0; queue_no < nvqs; queue_no++) {
>           if (!virtio_queue_get_num(vdev, queue_no)) {
>               break;
>           }
> -        vector = virtio_queue_vector(vdev, queue_no);
> +        ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> +        if (ret < 0) {
> +            break;


So this suppresses the check below? (you had a similar check that is 
done in virtio_pci_get_notifier).

Thanks


> +        }
>           if (vector >= msix_nr_vectors_allocated(dev)) {
>               continue;
>           }
> @@ -736,8 +760,6 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
>            * 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);
> @@ -754,8 +776,10 @@ undo:
>               continue;
>           }
>           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 = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> +            if (ret < 0) {
> +                break;
> +            }
>               kvm_virtio_pci_irqfd_release(proxy, n, vector);
>           }
>           kvm_virtio_pci_vq_vector_release(proxy, vector);
> @@ -770,13 +794,16 @@ static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
>       unsigned int vector;
>       int queue_no;
>       VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> -    VirtQueue *vq;
>       EventNotifier *n;
> +    int ret ;
>       for (queue_no = 0; queue_no < nvqs; queue_no++) {
>           if (!virtio_queue_get_num(vdev, queue_no)) {
>               break;
>           }
> -        vector = virtio_queue_vector(vdev, queue_no);
> +        ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> +        if (ret < 0) {
> +            break;
> +        }
>           if (vector >= msix_nr_vectors_allocated(dev)) {
>               continue;
>           }
> @@ -784,8 +811,6 @@ static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
>            * Otherwise, it was cleaned when masked 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);
>               kvm_virtio_pci_irqfd_release(proxy, n, vector);
>           }
>           kvm_virtio_pci_vq_vector_release(proxy, vector);