netdev - Re: [PATCH v9 22/32] virtio_pci: queue_reset: extract the logic of active vq for modern pci

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Date:   Thu, 14 Apr 2022 17:37:50 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc:     Jeff Dike <jdike@...toit.com>, Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        Vadim Pasternak <vadimp@...dia.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Cornelia Huck <cohuck@...hat.com>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        linux-um@...ts.infradead.org, netdev <netdev@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm <kvm@...r.kernel.org>,
        "open list:XDP (eXpress Data Path)" <bpf@...r.kernel.org>,
        virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH v9 22/32] virtio_pci: queue_reset: extract the logic of
 active vq for modern pci

On Thu, Apr 14, 2022 at 2:25 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> On Tue, 12 Apr 2022 14:58:19 +0800, Jason Wang <jasowang@...hat.com> wrote:
> >
> > 在 2022/4/6 上午11:43, Xuan Zhuo 写道:
> > > Introduce vp_active_vq() to configure vring to backend after vq attach
> > > vring. And configure vq vector if necessary.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> > > ---
> > >   drivers/virtio/virtio_pci_modern.c | 46 ++++++++++++++++++------------
> > >   1 file changed, 28 insertions(+), 18 deletions(-)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > > index 86d301f272b8..49a4493732cf 100644
> > > --- a/drivers/virtio/virtio_pci_modern.c
> > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > @@ -176,6 +176,29 @@ static void vp_reset(struct virtio_device *vdev)
> > >     vp_disable_cbs(vdev);
> > >   }
> > >
> > > +static int vp_active_vq(struct virtqueue *vq, u16 msix_vec)
> > > +{
> > > +   struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> > > +   struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > > +   unsigned long index;
> > > +
> > > +   index = vq->index;
> > > +
> > > +   /* activate the queue */
> > > +   vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
> > > +   vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
> > > +                           virtqueue_get_avail_addr(vq),
> > > +                           virtqueue_get_used_addr(vq));
> > > +
> > > +   if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
> > > +           msix_vec = vp_modern_queue_vector(mdev, index, msix_vec);
> > > +           if (msix_vec == VIRTIO_MSI_NO_VECTOR)
> > > +                   return -EBUSY;
> > > +   }
> > > +
> > > +   return 0;
> > > +}
> > > +
> > >   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> > >   {
> > >     return vp_modern_config_vector(&vp_dev->mdev, vector);
> > > @@ -220,32 +243,19 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> > >
> > >     vq->num_max = num;
> > >
> > > -   /* activate the queue */
> > > -   vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
> > > -   vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
> > > -                           virtqueue_get_avail_addr(vq),
> > > -                           virtqueue_get_used_addr(vq));
> > > +   err = vp_active_vq(vq, msix_vec);
> > > +   if (err)
> > > +           goto err;
> > >
> > >     vq->priv = (void __force *)vp_modern_map_vq_notify(mdev, index, NULL);
> > >     if (!vq->priv) {
> > >             err = -ENOMEM;
> > > -           goto err_map_notify;
> > > -   }
> > > -
> > > -   if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
> > > -           msix_vec = vp_modern_queue_vector(mdev, index, msix_vec);
> > > -           if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
> > > -                   err = -EBUSY;
> > > -                   goto err_assign_vector;
> > > -           }
> > > +           goto err;
> > >     }
> > >
> > >     return vq;
> > >
> > > -err_assign_vector:
> > > -   if (!mdev->notify_base)
> > > -           pci_iounmap(mdev->pci_dev, (void __iomem __force *)vq->priv);
> >
> >
> > We need keep this or anything I missed?
>
> I think so, after modification, vp_modern_map_vq_notify is the last step before
> returning vq. If it fails, then vq->priv is equal to NULL, so there is no need
> to execute pci_iounmap.
>
> Did I miss something?

Nope I miss that the vector is configured before the mapping.

So

Acked-by: Jason Wang <jasowang@...hat.com>

Thanks

>
> Thanks.
>
> >
> > Thanks
> >
> >
> > > -err_map_notify:
> > > +err:
> > >     vring_del_virtqueue(vq);
> > >     return ERR_PTR(err);
> > >   }
> >
>