[PATCH V4 4/9] mshv: Add ioctl support for MSHV-VFIO bridge device

[Mukesh R <mrathor@linux.microsoft.com>]

Add ioctl support for MSHV devices for a partition. At present only VFIO
device types are supported, but more could be added. At a high level, a
partition ioctl to create device verifies it is of type VFIO and does some
setup for bridge code in mshv_vfio.c.  Adapted from KVM device ioctls.

Co-developed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Mukesh R <mrathor@linux.microsoft.com>
---
 drivers/hv/mshv_root_main.c | 119 ++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 02c107458be9..a36e54bfa064 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1625,6 +1625,122 @@ mshv_partition_ioctl_initialize(struct mshv_partition *partition)
 	return ret;
 }
 
+static long mshv_device_attr_ioctl(struct mshv_device *mshv_dev, int cmd,
+				   ulong uarg)
+{
+	struct mshv_device_attr attr;
+	const struct mshv_device_ops *devops = mshv_dev->device_ops;
+
+	if (copy_from_user(&attr, (void __user *)uarg, sizeof(attr)))
+		return -EFAULT;
+
+	switch (cmd) {
+	case MSHV_SET_DEVICE_ATTR:
+		if (devops->device_set_attr)
+			return devops->device_set_attr(mshv_dev, &attr);
+		break;
+	case MSHV_HAS_DEVICE_ATTR:
+		if (devops->device_has_attr)
+			return devops->device_has_attr(mshv_dev, &attr);
+		break;
+	}
+
+	return -EPERM;
+}
+
+static long mshv_device_fop_ioctl(struct file *filp, unsigned int cmd,
+				  ulong uarg)
+{
+	struct mshv_device *mshv_dev = filp->private_data;
+
+	switch (cmd) {
+	case MSHV_SET_DEVICE_ATTR:
+	case MSHV_HAS_DEVICE_ATTR:
+		return mshv_device_attr_ioctl(mshv_dev, cmd, uarg);
+	}
+
+	return -ENOTTY;
+}
+
+static int mshv_device_fop_release(struct inode *inode, struct file *filp)
+{
+	struct mshv_device *mshv_dev = filp->private_data;
+	struct mshv_partition *partition = mshv_dev->device_pt;
+
+	if (mshv_dev->device_ops->device_release) {
+		mutex_lock(&partition->pt_mutex);
+		hlist_del(&mshv_dev->device_ptnode);
+		mshv_dev->device_ops->device_release(mshv_dev);
+		mutex_unlock(&partition->pt_mutex);
+	}
+
+	mshv_partition_put(partition);
+	return 0;
+}
+
+static const struct file_operations mshv_device_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = mshv_device_fop_ioctl,
+	.release = mshv_device_fop_release,
+};
+
+static long mshv_partition_ioctl_create_device(struct mshv_partition *partition,
+					       void __user *uarg)
+{
+	long rc;
+	struct mshv_create_device devargk;
+	struct mshv_device *mshv_dev;
+	const struct mshv_device_ops *vfio_ops;
+
+	if (copy_from_user(&devargk, uarg, sizeof(devargk)))
+		return -EFAULT;
+
+	/* At present, only VFIO is supported */
+	if (devargk.type != MSHV_DEV_TYPE_VFIO)
+		return -ENODEV;
+
+	if (devargk.flags & MSHV_CREATE_DEVICE_TEST)
+		return 0;
+
+	if (devargk.flags)	/* currently, only MSHV_CREATE_DEVICE_TEST */
+		return -EINVAL;
+
+	/* This is freed later by mshv_vfio_release_device() */
+	mshv_dev = kzalloc_obj(*mshv_dev);
+	if (mshv_dev == NULL)
+		return -ENOMEM;
+
+	vfio_ops = &mshv_vfio_device_ops;
+	mshv_dev->device_ops = vfio_ops;
+	mshv_dev->device_pt = partition;
+
+	rc = vfio_ops->device_create(mshv_dev);
+	if (rc < 0) {
+		kfree(mshv_dev);
+		return rc;
+	}
+
+	hlist_add_head(&mshv_dev->device_ptnode, &partition->pt_devices);
+
+	mshv_partition_get(partition);
+	rc = anon_inode_getfd(vfio_ops->device_name, &mshv_device_fops,
+			      mshv_dev, O_RDWR | O_CLOEXEC);
+	if (rc < 0)
+		goto undo_out;
+
+	devargk.fd = rc;
+	if (copy_to_user(uarg, &devargk, sizeof(devargk)))
+		return -EFAULT;    /* cleanup in mshv_device_fop_release() */
+
+	return 0;
+
+undo_out:
+	hlist_del(&mshv_dev->device_ptnode);
+	vfio_ops->device_release(mshv_dev);    /* will kfree(mshv_dev) */
+	mshv_partition_put(partition);
+	return rc;
+}
+
 static long
 mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 {
@@ -1661,6 +1777,9 @@ mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 	case MSHV_ROOT_HVCALL:
 		ret = mshv_ioctl_passthru_hvcall(partition, true, uarg);
 		break;
+	case MSHV_CREATE_DEVICE:
+		ret = mshv_partition_ioctl_create_device(partition, uarg);
+		break;
 	default:
 		ret = -ENOTTY;
 	}
-- 
2.51.2.vfs.0.1