Re: [PATCH v7 08/10] virtio-pci: decouple virtqueue from kvm_virtio_pci_vector_use

[Cindy Lu]

On Thu, Jun 3, 2021 at 2:39 PM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2021/6/2 上午11:47, Cindy Lu 写道:
> > inorder
>
>
> s/inorder/In order/
>
>
> > to support configure interrupt, we need to decouple
> > virtqueue from vector use and vector release function
> > this patch introduce vector_release_one and vector_use_one
> > to support one vector.
> >
> > Signed-off-by: Cindy Lu <lulu@redhat.com>
>
>
> I think we need to reorder the patches to let such decoupling comes
> first in this series.
>
>
> > ---
> >   hw/virtio/virtio-pci.c | 122 ++++++++++++++++++++---------------------
> >   1 file changed, 61 insertions(+), 61 deletions(-)
> >
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index 6a4ef413a4..f863c89de6 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];
> > @@ -710,85 +709,86 @@ 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 kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
> > +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);
> > -    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 (queue_no == VIRTIO_CONFIG_IRQ_IDX) {
> > +        return -1;
> > +    } else {
> >           if (!virtio_queue_get_num(vdev, queue_no)) {
> > -            break;
> > -        }
> > -        vector = virtio_queue_vector(vdev, queue_no);
> > -        if (vector >= msix_nr_vectors_allocated(dev)) {
> > -            continue;
> > -        }
> > -        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) {
> > -            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;
> > -            }
> > +            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_one(VirtIOPCIProxy *proxy, int 
> > queue_no)
> > +{
>
>
> To ease the reviewer, let's separate this patch into two.
>
> 1) factoring out the core logic
> 2) decouple the vq
>
> Thanks
>
Thanks Jason, I will change this part
>
> > +    unsigned int vector;
> > +    int ret;
> > +    EventNotifier *n;
> > +    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) {
> > -            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);
> > +    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);
> > -    VirtQueue *vq;
> >       EventNotifier *n;
> > +    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;
> > -        }
> > -        vector = virtio_queue_vector(vdev, queue_no);
> > -        if (vector >= msix_nr_vectors_allocated(dev)) {
> > -            continue;
> > -        }
> > -        /* 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) {
> > -            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);
> > +        kvm_virtio_pci_vector_release_one(proxy, queue_no);
> >       }
> >   }
> >
>