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

[Cindy Lu <lulu@redhat.com>]

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*/
+	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