Re: [RE]: [PATCH v3 10/10] vfio/ccw: Move the lifecycle of the struct vfio_ccw_private to the mdev

On Wed, 2021-11-24 at 12:25 +0000, Liu, Yi L wrote:

...

From: Jason Gunthorpe jgg@nvidia.com 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, 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@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 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