Re: [PATCH v3 2/6] vfio: ccw: Rework subchannel state on setup

Eric Farman
2018-12-18T17:44:17Z

My questions to this patch from the original RFC series are still
outstanding. :(

https://marc.info/?l=linux-s390&m=154223063716128&w=2

On 11/28/2018 07:41 AM, Pierre Morel wrote:
> The subchannel enablement and the according setting to the
> VFIO_CCW_STATE_STANDBY state should only be done when all
> parts of the VFIO mediated device have been initialized
> i.e. after the mediated device has been successfully opened.
>
> Let's stay in VFIO_CCW_STATE_NOT_OPER until the mediated
> device has been opened and set the VFIO_CCW_STATE_STANDBY
> on a successful open.
>
> On release the state is set back to VFIO_CCW_STATE_NOT_OPER
> by vfio_ccw_sch_quiesce().
>
> When the mediated device is closed, disable the sub channel
> by calling vfio_ccw_sch_quiesce().
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
> drivers/s390/cio/vfio_ccw_async.c | 11 +++++++++++

Ah, this series is built on Connie's async changes. Okay. [1]

> drivers/s390/cio/vfio_ccw_drv.c | 10 +---------
> drivers/s390/cio/vfio_ccw_ops.c | 27 +++++++++++++++++++++------
> drivers/s390/cio/vfio_ccw_private.h | 1 +
> 4 files changed, 34 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/s390/cio/vfio_ccw_async.c b/drivers/s390/cio/vfio_ccw_async.c
> index 8c7f51d..033574e 100644
> --- a/drivers/s390/cio/vfio_ccw_async.c
> +++ b/drivers/s390/cio/vfio_ccw_async.c
> @@ -76,6 +76,17 @@ const struct vfio_ccw_regops vfio_ccw_async_region_ops = {
> .release = vfio_ccw_async_region_release,
> };
>
> +void vfio_ccw_unregister_async_dev_regions(struct vfio_ccw_private *private)
> +{
> + int i;
> +
> + for (i = 0; i < private->num_regions; i++)
> + private->region[i].ops->release(private, &private->region[i]);
> + private->num_regions = 0;
> + kfree(private->region);
> + private->region = NULL;
> +} > +
> int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private)
> {
> return vfio_ccw_register_dev_region(private,
> diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
> index bce7fed..d3527b6 100644
> --- a/drivers/s390/cio/vfio_ccw_drv.c
> +++ b/drivers/s390/cio/vfio_ccw_drv.c
> @@ -133,26 +133,18 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
> private->sch = sch;
> dev_set_drvdata(&sch->dev, private);
>
> - spin_lock_irq(sch->lock);
> private->state = VFIO_CCW_STATE_NOT_OPER;
> sch->isc = VFIO_CCW_ISC;
> - ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
> - spin_unlock_irq(sch->lock);
> - if (ret)
> - goto out_free;
>
> INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);
> atomic_set(&private->avail, 1);
> - private->state = VFIO_CCW_STATE_STANDBY;
>
> ret = vfio_ccw_mdev_reg(sch);
> if (ret)
> - goto out_disable;
> + goto out_free;
>
> return 0;
>
> -out_disable:
> - cio_disable_subchannel(sch);
> out_free:
> dev_set_drvdata(&sch->dev, NULL);
> if (private->cmd_region)
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> index 0e1f7f7b..cc7d46a 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -113,14 +113,11 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> struct vfio_ccw_private *private =
> dev_get_drvdata(mdev_parent_dev(mdev));
>
> - if (private->state == VFIO_CCW_STATE_NOT_OPER)
> - return -ENODEV;
> -
> if (atomic_dec_if_positive(&private->avail) < 0)
> return -EPERM;
>
> private->mdev = mdev;
> - private->state = VFIO_CCW_STATE_IDLE;
> + private->state = VFIO_CCW_STATE_NOT_OPER;
>
> return 0;
> }
> @@ -148,6 +145,7 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev)
> struct vfio_ccw_private *private =
> dev_get_drvdata(mdev_parent_dev(mdev));
> unsigned long events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
> + struct subchannel *sch = private->sch;
> int ret;
>
> private->nb.notifier_call = vfio_ccw_mdev_notifier;
> @@ -159,8 +157,24 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev)
>
> ret = vfio_ccw_register_async_dev_regions(private);
> if (ret)
> - vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
> - &private->nb);
> + goto err_regions;
> +
> + spin_lock_irq(private->sch->lock);
> + ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
> + if (ret)
> + goto err_enable;
> +
> + private->state = VFIO_CCW_STATE_STANDBY;
> + spin_unlock_irq(sch->lock);
> + return 0;
> +
> +err_enable:
> + spin_unlock_irq(sch->lock);
> + vfio_ccw_unregister_async_dev_regions(private);
> +
> +err_regions:
> + vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
> + &private->nb);
> return ret;
> }
>
> @@ -170,6 +184,7 @@ static void vfio_ccw_mdev_release(struct mdev_device *mdev)
> dev_get_drvdata(mdev_parent_dev(mdev));
> int i;
>
> + vfio_ccw_sch_quiesce(private->sch);
> vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
> &private->nb);

[1] If Connie's async patches go in first, then the stuff in your
"vfio_ccw_unregister_async_dev_regions" is also added here. That could
be removed and replaced with a call to your new function, yes?

>
> diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
> index 1a41a14..5d799b7 100644
> --- a/drivers/s390/cio/vfio_ccw_private.h
> +++ b/drivers/s390/cio/vfio_ccw_private.h
> @@ -54,6 +54,7 @@ int vfio_ccw_register_dev_region(struct vfio_ccw_private *private,
> size_t size, u32 flags, void *data);
>
> int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private);
> +void vfio_ccw_unregister_async_dev_regions(struct vfio_ccw_private *private);
>
> /**
> * struct vfio_ccw_private
>