linux-kernel - Re: [PATCH v4 4/5] vduse: Add file operation for mmap

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Date: Fri, 8 Mar 2024 14:07:50 +0800
From: Jason Wang <jasowang@...hat.com>
To: Cindy Lu <lulu@...hat.com>
Cc: mst@...hat.com, xieyongji@...edance.com, linux-kernel@...r.kernel.org, 
	maxime.coquelin@...hat.com
Subject: Re: [PATCH v4 4/5] vduse: Add file operation for mmap

On Wed, Feb 7, 2024 at 1:47 PM Cindy Lu <lulu@...hat.com> wrote:
>
> Add the operation for mmap, This function  will be used by the user space
> application to map the pages to the user space.
>
> Signed-off-by: Cindy Lu <lulu@...hat.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 57 ++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 2da659d5f4a8..083fe0047677 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1465,6 +1465,61 @@ static struct vduse_dev *vduse_dev_get_from_minor(int minor)
>         return dev;
>  }
>
> +static vm_fault_t vduse_vm_fault(struct vm_fault *vmf)
> +{
> +       struct vduse_dev *dev = vmf->vma->vm_file->private_data;
> +       struct vm_area_struct *vma = vmf->vma;
> +       u16 index = vma->vm_pgoff;
> +       struct vduse_virtqueue *vq;
> +       unsigned long vaddr;
> +
> +       /* index 1+vq_number page reserved for virtqueue state*/

This comment seem wrong?

THanks


> +       vq = dev->vqs[index];
> +       vaddr = vq->vdpa_reconnect_vaddr;
> +       if (remap_pfn_range(vma, vmf->address & PAGE_MASK,
> +                           PFN_DOWN(virt_to_phys((void *)vaddr)), PAGE_SIZE,
> +                           vma->vm_page_prot))
> +               return VM_FAULT_SIGBUS;
> +       return VM_FAULT_NOPAGE;
> +}
> +
> +static const struct vm_operations_struct vduse_vm_ops = {
> +       .fault = vduse_vm_fault,
> +};
> +
> +static int vduse_dev_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> +       struct vduse_dev *dev = file->private_data;
> +       unsigned long vaddr = 0;
> +       unsigned long index = vma->vm_pgoff;
> +       struct vduse_virtqueue *vq;
> +
> +       if (vma->vm_end - vma->vm_start != PAGE_SIZE)
> +               return -EINVAL;
> +       if ((vma->vm_flags & VM_SHARED) == 0)
> +               return -EINVAL;
> +
> +       if (index > dev->vq_num)
> +               return -EINVAL;
> +
> +       vq = dev->vqs[index];
> +       vaddr = vq->vdpa_reconnect_vaddr;
> +       if (vaddr == 0)
> +               return -EOPNOTSUPP;
> +
> +       if (virt_to_phys((void *)vaddr) & (PAGE_SIZE - 1))
> +               return -EINVAL;
> +
> +       /* Check if the Userspace App mapped the correct size */
> +       if (vma->vm_end - vma->vm_start != PAGE_SIZE)
> +               return -EOPNOTSUPP;
> +
> +       vm_flags_set(vma, VM_DONTEXPAND);
> +       vma->vm_ops = &vduse_vm_ops;
> +
> +       return 0;
> +}
> +
>  static int vduse_dev_open(struct inode *inode, struct file *file)
>  {
>         int ret;
> @@ -1497,6 +1552,8 @@ static const struct file_operations vduse_dev_fops = {
>         .unlocked_ioctl = vduse_dev_ioctl,
>         .compat_ioctl   = compat_ptr_ioctl,
>         .llseek         = noop_llseek,
> +       .mmap           = vduse_dev_mmap,
> +
>  };
>
>  static ssize_t irq_cb_affinity_show(struct vduse_virtqueue *vq, char *buf)
> --
> 2.43.0
>