> From: Eric Farman <farman@xxxxxxxxxxxxx>
> Sent: Tuesday, November 30, 2021 1:18 AM
>
> On Wed, 2021-11-24 at 12:25 +0000, Liu, Yi L wrote:
> > > From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > > Sent: Fri, 1 Oct 2021 14:52:51 -0300
> > >
> > > The css_driver's main purpose is to create/destroy the mdev and
> > > relay the
> > > shutdown, irq, sch_event, and chp_event css_driver ops to the
> > > single
> > > created vfio_device, if it exists.
> > >
> > > Reframe the boundary where the css_driver domain switches to the
> > > vfio
> > > domain by using rcu to read and refcount the vfio_device out of the
> > > sch's
> > > drvdata. The mdev probe/remove will manage the drvdata of the
> > > parent.
> > >
> > > The vfio core code refcounting thus guarantees that when a
> > > css_driver
> > > callback is running the vfio_device is registered, simplifying the
> > > understanding of the whole lifecycle.
> > >
> > > Finally the vfio_ccw_private is allocated/freed during probe/remove
> > > of the
> > > mdev like any other vfio_device struct.
> >
> > Hi Eric,
> >
> > how about the status of this patch?
>
> Hi YiLiu,
>
> To be honest I never got this far in the series, as the middle of the
> series got into some more involved rework than I had the bandwidth to
> consider. Not sure I'll be able to do anything with it before the year
> end holiday, but I've noted your interest in getting this in line with
> the rest of vfio_device so I don't drop it too far down the list.
thanks. look forward to your further thoughts on it. e.g. the rework
things and gaps in this cleanup.
Regards,
Yi Liu
> Thanks,
> Eric
>
> > I found it is a good clean up to make
> > vfio ccw behave same with other vfio_device users. Also, I'd like to
> > do a clean up to consolidate the vfio_device allocation which needs the
> > vfio ccw private allocation happen in the mdev probe. So it would be nice
> > to build the cleanup based on this patch.
> >
> > Regards,
> > Yi Liu
> >
> > > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > > ---
> > > drivers/s390/cio/vfio_ccw_drv.c | 67 ++++++++++++++-----------
> > > ----
> > > drivers/s390/cio/vfio_ccw_ops.c | 40 +++++++----------
> > > drivers/s390/cio/vfio_ccw_private.h | 23 +++++++++-
> > > 3 files changed, 69 insertions(+), 61 deletions(-)
> > >
> > > diff --git a/drivers/s390/cio/vfio_ccw_drv.c
> > > b/drivers/s390/cio/vfio_ccw_drv.c
> > > index 18ad047811d111..c5582fc9c46c9e 100644
> > > --- a/drivers/s390/cio/vfio_ccw_drv.c
> > > +++ b/drivers/s390/cio/vfio_ccw_drv.c
> > > @@ -86,13 +86,19 @@ static void vfio_ccw_crw_todo(struct
> > > work_struct *work)
> > > */
> > > static void vfio_ccw_sch_irq(struct subchannel *sch)
> > > {
> > > - struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
> > > + struct vfio_ccw_private *private = vfio_ccw_get_priv(sch);
> > > +
> > > + /* IRQ should not be delivered after the mdev is destroyed */
> > > + if (WARN_ON(!private))
> > > + return;
> > >
> > > inc_irq_stat(IRQIO_CIO);
> > > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
> > > + vfio_device_put(&private->vdev);
> > > }
> > >
> > > -static struct vfio_ccw_private *vfio_ccw_alloc_private(struct
> > > subchannel *sch)
> > > +struct vfio_ccw_private *vfio_ccw_alloc_private(struct mdev_device
> > > *mdev,
> > > + struct subchannel *sch)
> > > {
> > > struct vfio_ccw_private *private;
> > >
> > > @@ -100,6 +106,8 @@ static struct vfio_ccw_private
> > > *vfio_ccw_alloc_private(struct subchannel *sch)
> > > if (!private)
> > > return ERR_PTR(-ENOMEM);
> > >
> > > + vfio_init_group_dev(&private->vdev, &mdev->dev,
> > > + &vfio_ccw_dev_ops);
> > > private->sch = sch;
> > > mutex_init(&private->io_mutex);
> > > private->state = VFIO_CCW_STATE_CLOSED;
> > > @@ -145,11 +153,12 @@ static struct vfio_ccw_private
> > > *vfio_ccw_alloc_private(struct subchannel *sch)
> > > kfree(private->cp.guest_cp);
> > > out_free_private:
> > > mutex_destroy(&private->io_mutex);
> > > + vfio_uninit_group_dev(&private->vdev);
> > > kfree(private);
> > > return ERR_PTR(-ENOMEM);
> > > }
> > >
> > > -static void vfio_ccw_free_private(struct vfio_ccw_private
> > > *private)
> > > +void vfio_ccw_free_private(struct vfio_ccw_private *private)
> > > {
> > > struct vfio_ccw_crw *crw, *temp;
> > >
> > > @@ -164,14 +173,14 @@ static void vfio_ccw_free_private(struct
> > > vfio_ccw_private *private)
> > > kmem_cache_free(vfio_ccw_io_region, private->io_region);
> > > kfree(private->cp.guest_cp);
> > > mutex_destroy(&private->io_mutex);
> > > - kfree(private);
> > > + vfio_uninit_group_dev(&private->vdev);
> > > + kfree_rcu(private, rcu);
> > > }
> > >
> > > static int vfio_ccw_sch_probe(struct subchannel *sch)
> > > {
> > > struct pmcw *pmcw = &sch->schib.pmcw;
> > > - struct vfio_ccw_private *private;
> > > - int ret = -ENOMEM;
> > > + int ret;
> > >
> > > if (pmcw->qf) {
> > > dev_warn(&sch->dev, "vfio: ccw: does not support QDIO:
> > > %s\n",
> > > @@ -179,15 +188,9 @@ static int vfio_ccw_sch_probe(struct
> > > subchannel *sch)
> > > return -ENODEV;
> > > }
> > >
> > > - private = vfio_ccw_alloc_private(sch);
> > > - if (IS_ERR(private))
> > > - return PTR_ERR(private);
> > > -
> > > - dev_set_drvdata(&sch->dev, private);
> > > -
> > > - ret = vfio_ccw_mdev_reg(sch);
> > > + ret = mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
> > > if (ret)
> > > - goto out_free;
> > > + return ret;
> > >
> > > if (dev_get_uevent_suppress(&sch->dev)) {
> > > dev_set_uevent_suppress(&sch->dev, 0);
> > > @@ -198,22 +201,11 @@ static int vfio_ccw_sch_probe(struct
> > > subchannel *sch)
> > > sch->schid.cssid, sch->schid.ssid,
> > > sch->schid.sch_no);
> > > return 0;
> > > -
> > > -out_free:
> > > - dev_set_drvdata(&sch->dev, NULL);
> > > - vfio_ccw_free_private(private);
> > > - return ret;
> > > }
> > >
> > > static void vfio_ccw_sch_remove(struct subchannel *sch)
> > > {
> > > - struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
> > > -
> > > - vfio_ccw_mdev_unreg(sch);
> > > -
> > > - dev_set_drvdata(&sch->dev, NULL);
> > > -
> > > - vfio_ccw_free_private(private);
> > > + mdev_unregister_device(&sch->dev);
> > >
> > > VFIO_CCW_MSG_EVENT(4, "unbound from
> subchannel %x.%x.%04x\n",
> > > sch->schid.cssid, sch->schid.ssid,
> > > @@ -222,10 +214,14 @@ static void vfio_ccw_sch_remove(struct
> > > subchannel *sch)
> > >
> > > static void vfio_ccw_sch_shutdown(struct subchannel *sch)
> > > {
> > > - struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
> > > + struct vfio_ccw_private *private = vfio_ccw_get_priv(sch);
> > > +
> > > + if (!private)
> > > + return;
> > >
> > > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);
> > > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_BROKEN);
> > > + vfio_device_put(&private->vdev);
> > > }
> > >
> > > /**
> > > @@ -240,14 +236,14 @@ static void vfio_ccw_sch_shutdown(struct
> > > subchannel *sch)
> > > */
> > > static int vfio_ccw_sch_event(struct subchannel *sch, int process)
> > > {
> > > - struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
> > > + struct vfio_ccw_private *private = vfio_ccw_get_priv(sch);
> > > unsigned long flags;
> > > int rc = -EAGAIN;
> > >
> > > - spin_lock_irqsave(sch->lock, flags);
> > > - if (!device_is_registered(&sch->dev))
> > > - goto out_unlock;
> > > + if (!private)
> > > + return -EAGAIN;
> > >
> > > + spin_lock_irqsave(sch->lock, flags);
> > > if (work_pending(&sch->todo_work))
> > > goto out_unlock;
> > >
> > > @@ -260,7 +256,7 @@ static int vfio_ccw_sch_event(struct subchannel
> > > *sch, int process)
> > >
> > > out_unlock:
> > > spin_unlock_irqrestore(sch->lock, flags);
> > > -
> > > + vfio_device_put(&private->vdev);
> > > return rc;
> > > }
> > >
> > > @@ -294,7 +290,7 @@ static void vfio_ccw_queue_crw(struct
> > > vfio_ccw_private *private,
> > > static int vfio_ccw_chp_event(struct subchannel *sch,
> > > struct chp_link *link, int event)
> > > {
> > > - struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
> > > + struct vfio_ccw_private *private = vfio_ccw_get_priv(sch);
> > > int mask = chp_ssd_get_mask(&sch->ssd_info, link);
> > > int retry = 255;
> > >
> > > @@ -307,8 +303,10 @@ static int vfio_ccw_chp_event(struct
> > > subchannel *sch,
> > > sch->schid.ssid, sch->schid.sch_no,
> > > mask, event);
> > >
> > > - if (cio_update_schib(sch))
> > > + if (cio_update_schib(sch)) {
> > > + vfio_device_put(&private->vdev);
> > > return -ENODEV;
> > > + }
> > >
> > > switch (event) {
> > > case CHP_VARY_OFF:
> > > @@ -338,6 +336,7 @@ static int vfio_ccw_chp_event(struct subchannel
> > > *sch,
> > > break;
> > > }
> > >
> > > + vfio_device_put(&private->vdev);
> > > return 0;
> > > }
> > >
> > > diff --git a/drivers/s390/cio/vfio_ccw_ops.c
> > > b/drivers/s390/cio/vfio_ccw_ops.c
> > > index 68aae25a0a4be0..414b11ea7eebf9 100644
> > > --- a/drivers/s390/cio/vfio_ccw_ops.c
> > > +++ b/drivers/s390/cio/vfio_ccw_ops.c
> > > @@ -17,8 +17,6 @@
> > >
> > > #include "vfio_ccw_private.h"
> > >
> > > -static const struct vfio_device_ops vfio_ccw_dev_ops;
> > > -
> > > static int vfio_ccw_mdev_reset(struct vfio_ccw_private *private)
> > > {
> > > /*
> > > @@ -88,26 +86,27 @@ static struct attribute_group
> > > *mdev_type_groups[] = {
> > >
> > > static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
> > > {
> > > - struct vfio_ccw_private *private = dev_get_drvdata(mdev-
> > > >dev.parent);
> > > + struct subchannel *sch = to_subchannel(mdev->dev.parent);
> > > + struct vfio_ccw_private *private;
> > > int ret;
> > >
> > > - memset(&private->vdev, 0, sizeof(private->vdev));
> > > - vfio_init_group_dev(&private->vdev, &mdev->dev,
> > > - &vfio_ccw_dev_ops);
> > > + private = vfio_ccw_alloc_private(mdev, sch);
> > > + if (IS_ERR(private))
> > > + return PTR_ERR(private);
> > >
> > > VFIO_CCW_MSG_EVENT(2, "mdev %s, sch %x.%x.%04x: create\n",
> > > - dev_name(private->vdev.dev),
> > > - private->sch->schid.cssid, private->sch-
> > > >schid.ssid,
> > > - private->sch->schid.sch_no);
> > > + dev_name(private->vdev.dev), sch-
> > > >schid.cssid,
> > > + sch->schid.ssid, sch->schid.sch_no);
> > >
> > > ret = vfio_register_emulated_iommu_dev(&private->vdev);
> > > if (ret)
> > > - goto err_init;
> > > + goto err_alloc;
> > > dev_set_drvdata(&mdev->dev, private);
> > > + dev_set_drvdata(&sch->dev, private);
> > > return 0;
> > >
> > > -err_init:
> > > - vfio_uninit_group_dev(&private->vdev);
> > > +err_alloc:
> > > + vfio_ccw_free_private(private);
> > > return ret;
> > > }
> > >
> > > @@ -120,8 +119,9 @@ static void vfio_ccw_mdev_remove(struct
> > > mdev_device *mdev)
> > > private->sch->schid.cssid, private->sch-
> > > >schid.ssid,
> > > private->sch->schid.sch_no);
> > >
> > > + dev_set_drvdata(&private->sch->dev, NULL);
> > > vfio_unregister_group_dev(&private->vdev);
> > > - vfio_uninit_group_dev(&private->vdev);
> > > + vfio_ccw_free_private(private);
> > > }
> > >
> > > static int vfio_ccw_mdev_open_device(struct vfio_device *vdev)
> > > @@ -595,7 +595,7 @@ static unsigned int
> > > vfio_ccw_get_available(struct mdev_type *mtype)
> > > return 1;
> > > }
> > >
> > > -static const struct vfio_device_ops vfio_ccw_dev_ops = {
> > > +const struct vfio_device_ops vfio_ccw_dev_ops = {
> > > .open_device = vfio_ccw_mdev_open_device,
> > > .close_device = vfio_ccw_mdev_close_device,
> > > .read = vfio_ccw_mdev_read,
> > > @@ -615,19 +615,9 @@ struct mdev_driver vfio_ccw_mdev_driver = {
> > > .get_available = vfio_ccw_get_available,
> > > };
> > >
> > > -static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
> > > +const struct mdev_parent_ops vfio_ccw_mdev_ops = {
> > > .owner = THIS_MODULE,
> > > .device_driver = &vfio_ccw_mdev_driver,
> > > .device_api = VFIO_DEVICE_API_CCW_STRING,
> > > .supported_type_groups = mdev_type_groups,
> > > };
> > > -
> > > -int vfio_ccw_mdev_reg(struct subchannel *sch)
> > > -{
> > > - return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
> > > -}
> > > -
> > > -void vfio_ccw_mdev_unreg(struct subchannel *sch)
> > > -{
> > > - mdev_unregister_device(&sch->dev);
> > > -}
> > > diff --git a/drivers/s390/cio/vfio_ccw_private.h
> > > b/drivers/s390/cio/vfio_ccw_private.h
> > > index 67ee9c624393b0..852ff94fc107d6 100644
> > > --- a/drivers/s390/cio/vfio_ccw_private.h
> > > +++ b/drivers/s390/cio/vfio_ccw_private.h
> > > @@ -24,6 +24,8 @@
> > > #include "css.h"
> > > #include "vfio_ccw_cp.h"
> > >
> > > +struct mdev_device;
> > > +
> > > #define VFIO_CCW_OFFSET_SHIFT 10
> > > #define VFIO_CCW_OFFSET_TO_INDEX(off) (off >>
> > > VFIO_CCW_OFFSET_SHIFT)
> > > #define VFIO_CCW_INDEX_TO_OFFSET(index) ((u64)(index) <<
> > > VFIO_CCW_OFFSET_SHIFT)
> > > @@ -69,6 +71,7 @@ struct vfio_ccw_crw {
> > > /**
> > > * struct vfio_ccw_private
> > > * @vdev: Embedded VFIO device
> > > + * @rcu: head for kfree_rcu()
> > > * @sch: pointer to the subchannel
> > > * @state: internal state of the device
> > > * @completion: synchronization helper of the I/O completion
> > > @@ -91,6 +94,7 @@ struct vfio_ccw_crw {
> > > */
> > > struct vfio_ccw_private {
> > > struct vfio_device vdev;
> > > + struct rcu_head rcu;
> > > struct subchannel *sch;
> > > int state;
> > > struct completion *completion;
> > > @@ -115,10 +119,25 @@ struct vfio_ccw_private {
> > > struct work_struct crw_work;
> > > } __aligned(8);
> > >
> > > -extern int vfio_ccw_mdev_reg(struct subchannel *sch);
> > > -extern void vfio_ccw_mdev_unreg(struct subchannel *sch);
> > > +struct vfio_ccw_private *vfio_ccw_alloc_private(struct mdev_device
> > > *mdev,
> > > + struct subchannel
> > > *sch);
> > > +void vfio_ccw_free_private(struct vfio_ccw_private *private);
> > >
> > > extern struct mdev_driver vfio_ccw_mdev_driver;
> > > +extern const struct mdev_parent_ops vfio_ccw_mdev_ops;
> > > +extern const struct vfio_device_ops vfio_ccw_dev_ops;
> > > +
> > > +static inline struct vfio_ccw_private *vfio_ccw_get_priv(struct
> > > subchannel *sch)
> > > +{
> > > + struct vfio_ccw_private *private;
> > > +
> > > + rcu_read_lock();
> > > + private = dev_get_drvdata(&sch->dev);
> > > + if (private && !vfio_device_try_get(&private->vdev))
> > > + private = NULL;
> > > + rcu_read_unlock();
> > > + return private;
> > > +}
> > >
> > > /*
> > > * States of the device statemachine.
> > > --
> > > 2.33.0
