[PATCH v5 4/5] vduse: Add file operation for mmap

[Cindy Lu]

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 <l...@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..7abe0c17cf0e 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 0~vq_number-1 page reserved for virtqueue state*/
+       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;
+
+       index = array_index_nospec(index, dev->vq_num);
+       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