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.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- 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 0e2edd96567a09..b86da53443bfd7 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 int 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, @@ -223,10 +215,14 @@ static int 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); }
/** @@ -241,14 +237,14 @@ 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;
@@ -261,7 +257,7 @@ 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; }
@@ -295,7 +291,7 @@ 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;
@@ -308,8 +304,10 @@ 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: @@ -339,6 +337,7 @@ 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 23004e67c492f6..04a10f37d64225 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_group_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.