From: Your Name <redacted>

Add the operation for mmap, The user space APP will
use this function to map the pages to userspace

Signed-off-by: Cindy Lu <redacted>
---
  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))
+		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;
+	}
+
+	vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
+	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)