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

Jason Wang
2024-03-08T06:08:05Z

On Wed, Feb 7, 2024 at 1:47 PM Cindy Lu <lulu@redhat.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@redhat.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
>