Commit 4f766173 authored by Cornelia Huck's avatar Cornelia Huck
Browse files

vfio-ccw: protect the I/O region 



Introduce a mutex to disallow concurrent reads or writes to the
I/O region. This makes sure that the data the kernel or user
space see is always consistent.

The same mutex will be used to protect the async region as well.

Reviewed-by: default avatarEric Farman <farman@linux.ibm.com>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent 690f6a15

drivers/s390/cio/vfio_ccw_drv.c

+3 −0
Original line number Diff line number Diff line
@@ -84,7 +84,9 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) 
		if (is_final)

			cp_free(&private->cp);

	}

	mutex_lock(&private->io_mutex);

	memcpy(private->io_region->irb_area, irb, sizeof(*irb));

	mutex_unlock(&private->io_mutex);



	if (private->io_trigger)

		eventfd_signal(private->io_trigger, 1);
@@ -129,6 +131,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) 


	private->sch = sch;

	dev_set_drvdata(&sch->dev, private);

	mutex_init(&private->io_mutex);



	spin_lock_irq(sch->lock);

	private->state = VFIO_CCW_STATE_NOT_OPER;

drivers/s390/cio/vfio_ccw_ops.c

+19 −9
Original line number Diff line number Diff line
@@ -169,16 +169,20 @@ static ssize_t vfio_ccw_mdev_read(struct mdev_device *mdev, 
{

	struct vfio_ccw_private *private;

	struct ccw_io_region *region;

	int ret;



	if (*ppos + count > sizeof(*region))

		return -EINVAL;



	private = dev_get_drvdata(mdev_parent_dev(mdev));

	mutex_lock(&private->io_mutex);

	region = private->io_region;

	if (copy_to_user(buf, (void *)region + *ppos, count))

		return -EFAULT;



	return count;

		ret = -EFAULT;

	else

		ret = count;

	mutex_unlock(&private->io_mutex);

	return ret;

}



static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
@@ -188,23 +192,29 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, 
{

	struct vfio_ccw_private *private;

	struct ccw_io_region *region;

	int ret;



	if (*ppos + count > sizeof(*region))

		return -EINVAL;



	private = dev_get_drvdata(mdev_parent_dev(mdev));

	if (!mutex_trylock(&private->io_mutex))

		return -EAGAIN;



	region = private->io_region;

	if (copy_from_user((void *)region + *ppos, buf, count))

		return -EFAULT;

	if (copy_from_user((void *)region + *ppos, buf, count)) {

		ret = -EFAULT;

		goto out_unlock;

	}



	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ);

	if (region->ret_code != 0) {

	if (region->ret_code != 0)

		private->state = VFIO_CCW_STATE_IDLE;

		return region->ret_code;

	}

	ret = (region->ret_code != 0) ? region->ret_code : count;



	return count;

out_unlock:

	mutex_unlock(&private->io_mutex);

	return ret;

}



static int vfio_ccw_mdev_get_device_info(struct vfio_device_info *info)

drivers/s390/cio/vfio_ccw_private.h

+2 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
 * @mdev: pointer to the mediated device

 * @nb: notifier for vfio events

 * @io_region: MMIO region to input/output I/O arguments/results

 * @io_mutex: protect against concurrent update of I/O regions

 * @cp: channel program for the current I/O operation

 * @irb: irb info received from interrupt

 * @scsw: scsw info
@@ -42,6 +43,7 @@ struct vfio_ccw_private { 
	struct mdev_device	*mdev;

	struct notifier_block	nb;

	struct ccw_io_region	*io_region;

	struct mutex		io_mutex;



	struct channel_program	cp;

	struct irb		irb;

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