Re: [PATCH v3 08/11] vfio/ccw: Create an OPEN FSM Event

[Matthew Rosato <mjrosato@linux.ibm.com>]

On 6/30/22 4:36 PM, Eric Farman wrote:
> Move the process of enabling a subchannel for use by vfio-ccw
> into the FSM, such that it can manage the sequence of lifecycle
> events for the device.
> 
> That is, if the FSM state is NOT_OPER(erational), then do the work
> that would enable the subchannel and move the FSM to STANDBY state.
> An attempt to perform this event again from any of the other operating
> states (IDLE, CP_PROCESSING, CP_PENDING) will convert the device back
> to NOT_OPER so the configuration process can be started again.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>

> ---
>   drivers/s390/cio/vfio_ccw_drv.c     |  9 ++-------
>   drivers/s390/cio/vfio_ccw_fsm.c     | 21 +++++++++++++++++++++
>   drivers/s390/cio/vfio_ccw_private.h |  1 +
>   3 files changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
> index fe87a2652a22..7d9189640da3 100644
> --- a/drivers/s390/cio/vfio_ccw_drv.c
> +++ b/drivers/s390/cio/vfio_ccw_drv.c
> @@ -231,15 +231,10 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
>   
>   	dev_set_drvdata(&sch->dev, private);
>   
> -	spin_lock_irq(sch->lock);
> -	sch->isc = VFIO_CCW_ISC;
> -	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
> -	spin_unlock_irq(sch->lock);
> -	if (ret)
> +	vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_OPEN);
> +	if (private->state == VFIO_CCW_STATE_NOT_OPER)
>   		goto out_free;
>   
> -	private->state = VFIO_CCW_STATE_STANDBY;
> -
>   	ret = mdev_register_device(&sch->dev, &vfio_ccw_mdev_driver);
>   	if (ret)
>   		goto out_disable;
> diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
> index 88e529a2e184..2811b2040490 100644
> --- a/drivers/s390/cio/vfio_ccw_fsm.c
> +++ b/drivers/s390/cio/vfio_ccw_fsm.c
> @@ -11,6 +11,8 @@
>   
>   #include <linux/vfio.h>
>   
> +#include <asm/isc.h>
> +
>   #include "ioasm.h"
>   #include "vfio_ccw_private.h"
>   
> @@ -368,6 +370,20 @@ static void fsm_irq(struct vfio_ccw_private *private,
>   		complete(private->completion);
>   }
>   
> +static void fsm_open(struct vfio_ccw_private *private,
> +		     enum vfio_ccw_event event)
> +{
> +	struct subchannel *sch = private->sch;
> +	int ret;
> +
> +	spin_lock_irq(sch->lock);
> +	sch->isc = VFIO_CCW_ISC;
> +	ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
> +	if (!ret)
> +		private->state = VFIO_CCW_STATE_STANDBY;
> +	spin_unlock_irq(sch->lock);
> +}
> +
>   /*
>    * Device statemachine
>    */
> @@ -377,29 +393,34 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
>   		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_error,
>   		[VFIO_CCW_EVENT_ASYNC_REQ]	= fsm_async_error,
>   		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_disabled_irq,
> +		[VFIO_CCW_EVENT_OPEN]		= fsm_open,
>   	},
>   	[VFIO_CCW_STATE_STANDBY] = {
>   		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,
>   		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_error,
>   		[VFIO_CCW_EVENT_ASYNC_REQ]	= fsm_async_error,
>   		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,
> +		[VFIO_CCW_EVENT_OPEN]		= fsm_notoper,
>   	},
>   	[VFIO_CCW_STATE_IDLE] = {
>   		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,
>   		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_request,
>   		[VFIO_CCW_EVENT_ASYNC_REQ]	= fsm_async_request,
>   		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,
> +		[VFIO_CCW_EVENT_OPEN]		= fsm_notoper,
>   	},
>   	[VFIO_CCW_STATE_CP_PROCESSING] = {
>   		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,
>   		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_retry,
>   		[VFIO_CCW_EVENT_ASYNC_REQ]	= fsm_async_retry,
>   		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,
> +		[VFIO_CCW_EVENT_OPEN]		= fsm_notoper,
>   	},
>   	[VFIO_CCW_STATE_CP_PENDING] = {
>   		[VFIO_CCW_EVENT_NOT_OPER]	= fsm_notoper,
>   		[VFIO_CCW_EVENT_IO_REQ]		= fsm_io_busy,
>   		[VFIO_CCW_EVENT_ASYNC_REQ]	= fsm_async_request,
>   		[VFIO_CCW_EVENT_INTERRUPT]	= fsm_irq,
> +		[VFIO_CCW_EVENT_OPEN]		= fsm_notoper,
>   	},
>   };
> diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
> index 4cfdd5fc0961..8dff1699a7d9 100644
> --- a/drivers/s390/cio/vfio_ccw_private.h
> +++ b/drivers/s390/cio/vfio_ccw_private.h
> @@ -142,6 +142,7 @@ enum vfio_ccw_event {
>   	VFIO_CCW_EVENT_IO_REQ,
>   	VFIO_CCW_EVENT_INTERRUPT,
>   	VFIO_CCW_EVENT_ASYNC_REQ,
> +	VFIO_CCW_EVENT_OPEN,
>   	/* last element! */
>   	NR_VFIO_CCW_EVENTS
>   };