On Wed, Jun 28, 2023 at 2:59 PM Cindy Lu <lulu@xxxxxxxxxx> wrote:
>
> From: Your Name <you@xxxxxxxxxxx>
>
> Add the operation for mmap, The user space APP will
> use this function to map the pages to userspace
Please be specific in the log. E.g why and what the main goal for this mmap.
>
> Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
> ---
> drivers/vdpa/vdpa_user/vduse_dev.c | 49 ++++++++++++++++++++++++++++++
> 1 file changed, 49 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index f845dc46b1db..1b833bf0ae37 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1313,6 +1313,54 @@ 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 vdpa_reconnect_info *info;
> + info = &dev->reconnect_info[index];
> +
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> + if (remap_pfn_range(vma, vmf->address & PAGE_MASK, PFN_DOWN(info->addr),
> + PAGE_SIZE, vma->vm_page_prot))
I'm not sure if this can work e.g do we want to use separate pages for
each virtqueue (I think the answer is yes).
> + return VM_FAULT_SIGBUS;
> + return VM_FAULT_NOPAGE;
> +}
> +
> +static const struct vm_operations_struct vduse_vm_ops = {
> + .fault = vduse_vm_fault,
> +};
> +
> +static int vduse_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> + struct vduse_dev *dev = file->private_data;
> + struct vdpa_reconnect_info *info;
> + unsigned long index = vma->vm_pgoff;
> +
> + if (vma->vm_end - vma->vm_start != PAGE_SIZE)
> + return -EINVAL;
> + if ((vma->vm_flags & VM_SHARED) == 0)
> + return -EINVAL;
> +
> + if (index > 65535)
> + return -EINVAL;
> +
> + info = &dev->reconnect_info[index];
> + if (info->addr & (PAGE_SIZE - 1))
> + return -EINVAL;
> + if (vma->vm_end - vma->vm_start != info->size) {
> + return -ENOTSUPP;
> + }
How can userspace know the correct size (info->size) here?
> +
> + vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
Why do you need VM_IO, VM_PFNMAP and VM_DONTDUMP here?
Thanks
> + vma->vm_ops = &vduse_vm_ops;
> +
> + return 0;
> +}
> +
> static int vduse_dev_open(struct inode *inode, struct file *file)
> {
> int ret;
> @@ -1345,6 +1393,7 @@ static const struct file_operations vduse_dev_fops = {
> .unlocked_ioctl = vduse_dev_ioctl,
> .compat_ioctl = compat_ptr_ioctl,
> .llseek = noop_llseek,
> + .mmap = vduse_mmap,
> };
>
> static struct vduse_dev *vduse_dev_create(void)
> --
> 2.34.3
>
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