Re: [PATCH v8 8/9] virtio-pci:decouple the single vector from the interrupt process

[Jason Wang <jasowang@redhat.com>]

在 2021/7/6 下午3:20, Cindy Lu 写道:
> use the kvm_virtio_pci_vector_use_one and _release_one
> these funtion is to deal with the single vector, the
> whole process will finish in a loop with vq number.
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>   hw/virtio/virtio-pci.c | 109 ++++++++++++++++-------------------------
>   1 file changed, 42 insertions(+), 67 deletions(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index fe06847b62..e43d5760ee 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -666,7 +666,6 @@ 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];
> @@ -733,87 +732,63 @@ static int virtio_pci_get_notifier(VirtIOPCIProxy *proxy, int queue_no,
>       return 0;
>   }
>   
> -static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
> +static int kvm_virtio_pci_vector_use_one(VirtIOPCIProxy *proxy, int queue_no)
>   {
> -    PCIDevice *dev = &proxy->pci_dev;
> -    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> -    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>       unsigned int vector;
> -    int ret, queue_no;
> +    int ret;
>       EventNotifier *n;
> -    for (queue_no = 0; queue_no < nvqs; queue_no++) {
> -        if (!virtio_queue_get_num(vdev, queue_no)) {
> -            break;
> -        }


So this check is not moved but deleted, is this intentional?


> -        ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> -        if (ret < 0) {
> -            break;
> -        }
> -        if (vector >= msix_nr_vectors_allocated(dev)) {
> -            continue;
> -        }


So did this?


> -        ret = kvm_virtio_pci_vq_vector_use(proxy, queue_no, vector);
> -        if (ret < 0) {
> -            goto undo;
> -        }
> -        /* 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) {
> -            ret = kvm_virtio_pci_irqfd_use(proxy, n, vector);
> -            if (ret < 0) {
> -                kvm_virtio_pci_vq_vector_release(proxy, vector);
> -                goto undo;
> -            }
> -        }
> +    ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +    ret = kvm_virtio_pci_vq_vector_use(proxy, vector);
> +    if (ret < 0) {
> +        goto undo;
> +    }
> +    ret = kvm_virtio_pci_irqfd_use(proxy, n, vector);
> +    if (ret < 0) {
> +        goto undo;
>       }
>       return 0;
> -
>   undo:
> -    while (--queue_no >= 0) {
> -        vector = virtio_queue_vector(vdev, queue_no);
> -        if (vector >= msix_nr_vectors_allocated(dev)) {
> -            continue;
> -        }
> -        if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> -            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);
> +    kvm_virtio_pci_irqfd_release(proxy, n, vector);
> +    return ret;
> +}
> +static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
> +{
> +    int queue_no;
> +    int ret = 0;
> +    for (queue_no = 0; queue_no < nvqs; queue_no++) {
> +        ret = kvm_virtio_pci_vector_use_one(proxy, queue_no);
>       }
>       return ret;
>   }
>   
> -static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
> +
> +static void kvm_virtio_pci_vector_release_one(VirtIOPCIProxy *proxy,
> +                        int queue_no)
>   {
> -    PCIDevice *dev = &proxy->pci_dev;
>       VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
>       unsigned int vector;
> -    int queue_no;
> -    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>       EventNotifier *n;
> -    int ret ;
> +    int ret;
> +    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> +    ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> +    if (ret < 0) {
> +        return;
> +    }
> +
> +    if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> +        kvm_virtio_pci_irqfd_release(proxy, n, vector);
> +    }
> +    kvm_virtio_pci_vq_vector_release(proxy, vector);
> +}
> +static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
> +{
> +    int queue_no;
> +
>       for (queue_no = 0; queue_no < nvqs; queue_no++) {
> -        if (!virtio_queue_get_num(vdev, queue_no)) {
> -            break;
> -        }


This is deleted by not removed.


> -        ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
> -        if (ret < 0) {
> -            break;
> -        }
> -        if (vector >= msix_nr_vectors_allocated(dev)) {
> -            continue;
> -        }


So did this.

Thanks


> -        /* If guest supports masking, clean up irqfd now.
> -         * Otherwise, it was cleaned when masked in the frontend.
> -         */
> -        if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
> -            kvm_virtio_pci_irqfd_release(proxy, n, vector);
> -        }
> -        kvm_virtio_pci_vq_vector_release(proxy, vector);
> +        kvm_virtio_pci_vector_release_one(proxy, queue_no);
>       }
>   }
>