Commit e5f84dba authored by Dong Jia Shi's avatar Dong Jia Shi Committed by Cornelia Huck
Browse files

vfio: ccw: return I/O results asynchronously 



Introduce a singlethreaded workqueue to handle the I/O interrupts.
With the work added to this queue, we store the I/O results to the
io_region of the subchannel, then signal the userspace program to
handle the results.

Signed-off-by: default avatarDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170317031743.40128-13-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent 120e214e

drivers/s390/cio/vfio_ccw_drv.c

+34 −24
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 
#include "css.h"

#include "vfio_ccw_private.h"



struct workqueue_struct *vfio_ccw_work_q;



/*

 * Helpers

 */
@@ -52,6 +54,7 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch) 


			spin_lock_irq(sch->lock);

			private->completion = NULL;

			flush_workqueue(vfio_ccw_work_q);

			ret = cio_cancel_halt_clear(sch, &iretry);

		};
@@ -63,18 +66,12 @@ out_unlock: 
	return ret;

}



static int doing_io(struct vfio_ccw_private *private, u32 intparm)

{

	return (private->intparm == intparm);

}



static int vfio_ccw_sch_io_helper(struct vfio_ccw_private *private)

{

	struct subchannel *sch;

	union orb *orb;

	int ccode;

	__u8 lpm;

	u32 intparm;



	sch = private->sch;
@@ -89,7 +86,7 @@ static int vfio_ccw_sch_io_helper(struct vfio_ccw_private *private) 
		 * Initialize device status information

		 */

		sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND;

		break;

		return 0;

	case 1:		/* Status pending */

	case 2:		/* Busy */

		return -EBUSY;
@@ -109,15 +106,26 @@ static int vfio_ccw_sch_io_helper(struct vfio_ccw_private *private) 
	default:

		return ccode;

	}

}



	intparm = (u32)(addr_t)sch;

	private->intparm = 0;

	wait_event(private->wait_q, doing_io(private, intparm));

static void vfio_ccw_sch_io_todo(struct work_struct *work)

{

	struct vfio_ccw_private *private;

	struct subchannel *sch;

	struct irb *irb;



	if (scsw_is_solicited(&private->irb.scsw))

		cp_update_scsw(&private->cp, &private->irb.scsw);

	private = container_of(work, struct vfio_ccw_private, io_work);

	irb = &private->irb;

	sch = private->sch;



	return 0;

	if (scsw_is_solicited(&irb->scsw)) {

		cp_update_scsw(&private->cp, &irb->scsw);

		cp_free(&private->cp);

	}

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



	if (private->io_trigger)

		eventfd_signal(private->io_trigger, 1);

}



/* Deal with the ccw command request from the userspace. */
@@ -126,7 +134,6 @@ int vfio_ccw_sch_cmd_request(struct vfio_ccw_private *private) 
	struct mdev_device *mdev = private->mdev;

	union orb *orb;

	union scsw *scsw = &private->scsw;

	struct irb *irb = &private->irb;

	struct ccw_io_region *io_region = &private->io_region;

	int ret;
@@ -147,11 +154,7 @@ int vfio_ccw_sch_cmd_request(struct vfio_ccw_private *private) 


		/* Start channel program and wait for I/O interrupt. */

		ret = vfio_ccw_sch_io_helper(private);

		if (!ret) {

			/* Get irb info and copy it to irb_area. */

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

		}



		if (!ret)

			cp_free(&private->cp);

	} else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {

		/* XXX: Handle halt. */
@@ -229,8 +232,8 @@ static void vfio_ccw_sch_irq(struct subchannel *sch) 


	irb = this_cpu_ptr(&cio_irb);

	memcpy(&private->irb, irb, sizeof(*irb));

	private->intparm = (u32)(addr_t)sch;

	wake_up(&private->wait_q);



	queue_work(vfio_ccw_work_q, &private->io_work);



	if (private->completion)

		complete(private->completion);
@@ -269,7 +272,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) 
	if (ret)

		goto out_rm_group;



	init_waitqueue_head(&private->wait_q);

	INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);

	atomic_set(&private->avail, 1);



	return 0;
@@ -367,10 +370,16 @@ static int __init vfio_ccw_sch_init(void) 
{

	int ret;



	vfio_ccw_work_q = create_singlethread_workqueue("vfio-ccw");

	if (!vfio_ccw_work_q)

		return -ENOMEM;



	isc_register(VFIO_CCW_ISC);

	ret = css_driver_register(&vfio_ccw_sch_driver);

	if (ret)

	if (ret) {

		isc_unregister(VFIO_CCW_ISC);

		destroy_workqueue(vfio_ccw_work_q);

	}



	return ret;

}
@@ -379,6 +388,7 @@ static void __exit vfio_ccw_sch_exit(void) 
{

	css_driver_unregister(&vfio_ccw_sch_driver);

	isc_unregister(VFIO_CCW_ISC);

	destroy_workqueue(vfio_ccw_work_q);

}

module_init(vfio_ccw_sch_init);

module_exit(vfio_ccw_sch_exit);

drivers/s390/cio/vfio_ccw_ops.c

+0 −3
Original line number Diff line number Diff line
@@ -202,9 +202,6 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, 
	if (region->ret_code != 0)

		return region->ret_code;



	if (private->io_trigger)

		eventfd_signal(private->io_trigger, 1);



	return count;

}

drivers/s390/cio/vfio_ccw_private.h

+3 −4
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 


#include <linux/completion.h>

#include <linux/eventfd.h>

#include <linux/workqueue.h>

#include <linux/vfio_ccw.h>



#include "css.h"
@@ -25,12 +26,11 @@ 
 * @mdev: pointer to the mediated device

 * @nb: notifier for vfio events

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

 * @wait_q: wait for interrupt

 * @intparm: record current interrupt parameter, used for wait interrupt

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

 * @irb: irb info received from interrupt

 * @scsw: scsw info

 * @io_trigger: eventfd ctx for signaling userspace I/O results

 * @io_work: work for deferral process of I/O handling

 */

struct vfio_ccw_private {

	struct subchannel	*sch;
@@ -40,13 +40,12 @@ struct vfio_ccw_private { 
	struct notifier_block	nb;

	struct ccw_io_region	io_region;



	wait_queue_head_t	wait_q;

	u32			intparm;

	struct channel_program	cp;

	struct irb		irb;

	union scsw		scsw;



	struct eventfd_ctx	*io_trigger;

	struct work_struct	io_work;

} __aligned(8);



extern int vfio_ccw_mdev_reg(struct subchannel *sch);

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