linux-kernel - Re: [RFC 3/4] vduse: Add the function for get/free the mapp pages

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Message-ID: <CACGkMEs2V2gqGOv1jd-ZrT-9HHnSU6dhC=1zUojHRDGCeG2E7w@mail.gmail.com>
Date:   Wed, 28 Jun 2023 16:11:27 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cindy Lu <lulu@...hat.com>
Cc:     mst@...hat.com, maxime.coquelin@...hat.com,
        xieyongji@...edance.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: Re: [RFC 3/4] vduse: Add the function for get/free the mapp pages

On Wed, Jun 28, 2023 at 2:59 PM Cindy Lu <lulu@...hat.com> wrote:
>
> From: Your Name <you@...mple.com>
>
> Add the function for get/free pages, ad this info
> will saved in dev->reconnect_info

I think this should be squashed to patch 2 otherwise it fixes a bug
that is introduced in patch 2?

>
> Signed-off-by: Cindy Lu <lulu@...hat.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 35 ++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 1b833bf0ae37..3df1256eccb4 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1313,6 +1313,35 @@ static struct vduse_dev *vduse_dev_get_from_minor(int minor)
>         return dev;
>  }
>
> +int vduse_get_vq_reconnnect(struct vduse_dev *dev, u16 idx)
> +{
> +       struct vdpa_reconnect_info *area;
> +       void *addr = (void *)get_zeroed_page(GFP_KERNEL);
> +
> +       area = &dev->reconnect_info[idx];
> +
> +       area->addr = virt_to_phys(addr);
> +       area->vaddr = (unsigned long)addr;
> +       area->size = PAGE_SIZE;
> +       area->index = idx;
> +
> +       return 0;
> +}
> +
> +int vduse_free_vq_reconnnect(struct vduse_dev *dev, u16 idx)
> +{
> +       struct vdpa_reconnect_info *area;
> +
> +       area = &dev->reconnect_info[idx];
> +       if ((area->size == PAGE_SIZE) && (area->addr != NULL)) {
> +               free_page(area->vaddr);
> +               area->size = 0;
> +               area->addr = 0;
> +               area->vaddr = 0;
> +       }
> +
> +       return 0;
> +}
>
>  static vm_fault_t vduse_vm_fault(struct vm_fault *vmf)
>  {
> @@ -1446,6 +1475,10 @@ static int vduse_destroy_dev(char *name)
>                 mutex_unlock(&dev->lock);
>                 return -EBUSY;
>         }
> +       for (int i = 0; i < dev->vq_num; i++) {
> +
> +               vduse_free_vq_reconnnect(dev, i);
> +       }
>         dev->connected = true;
>         mutex_unlock(&dev->lock);
>
> @@ -1583,6 +1616,8 @@ static int vduse_create_dev(struct vduse_dev_config *config,
>                 INIT_WORK(&dev->vqs[i].kick, vduse_vq_kick_work);
>                 spin_lock_init(&dev->vqs[i].kick_lock);
>                 spin_lock_init(&dev->vqs[i].irq_lock);
> +
> +               vduse_get_vq_reconnnect(dev, i);

Can we delay the allocated until fault?

Thanks

>         }
>
>         ret = idr_alloc(&vduse_idr, dev, 1, VDUSE_DEV_MAX, GFP_KERNEL);
> --
> 2.34.3
>