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 | 63 ++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 4c256fa31fc4..2c69f4004a6e 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c

@@ -1388,6 +1388,67 @@ 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;
+       struct vdpa_reconnect_info *info;
+
+       if (index == 0) {
+               info = &dev->reconnect_status;
+       } else {
+               vq = &dev->vqs[index - 1];
+               info = &vq->reconnect_info;
+       }
+       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_dev_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;
+       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 > 65535)
+               return -EINVAL;
+
+       if (index == 0) {
+               info = &dev->reconnect_status;
+       } else {
+               vq = &dev->vqs[index - 1];
+               info = &vq->reconnect_info;
+       }
+
+       if (info->index != index)
+               return -EINVAL;

+       vma->vm_ops = &vduse_vm_ops;
+
+       return 0;
+}
+
 static int vduse_dev_open(struct inode *inode, struct file *file)
 {
        int ret;

@@ -1420,6 +1481,8 @@ 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 struct vduse_dev *vduse_dev_create(void)
--

2.34.3