From: Kevin Tian <kevin.tian@intel.com>
To: Zhenyu Wang <zhenyuw@linux.intel.com>,
Zhi Wang <zhi.a.wang@intel.com>,
Jani Nikula <jani.nikula@linux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Eric Farman <farman@linux.ibm.com>,
Matthew Rosato <mjrosato@linux.ibm.com>,
Halil Pasic <pasic@linux.ibm.com>,
Vineeth Vijayan <vneethv@linux.ibm.com>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Tony Krowiak <akrowiak@linux.ibm.com>,
Jason Herne <jjherne@linux.ibm.com>,
Harald Freudenberger <freude@linux.ibm.com>,
Diana Craciun <diana.craciun@oss.nxp.com>,
Alex Williamson <alex.williamson@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Longfang Liu <liulongfang@huawei.com>,
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Yishai Hadas <yishaih@nvidia.com>,
Kevin Tian <kevin.tian@intel.com>,
Eric Auger <eric.auger@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
Leon Romanovsky <leon@kernel.org>,
Abhishek Sahu <abhsahu@nvidia.com>,
intel-gvt-dev@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
kvm@vger.kernel.org
Cc: Yi Liu <yi.l.liu@intel.com>
Subject: [PATCH 13/15] vfio/ccw: Use the new device life cycle helpers
Date: Sun, 28 Aug 2022 01:10:35 +0800 [thread overview]
Message-ID: <20220827171037.30297-14-kevin.tian@intel.com> (raw)
In-Reply-To: <20220827171037.30297-1-kevin.tian@intel.com>
ccw is the only exception which cannot use vfio_alloc_device() because
its private device structure is designed to serve both mdev and parent.
Life cycle of the parent is managed by css_driver so vfio_ccw_private
must be allocated/freed in css_driver probe/remove path instead of
conforming to vfio core life cycle for mdev.
Given that use a wait/completion scheme so the mdev remove path waits
after vfio_put_device() until receiving a completion notification from
@release. The completion indicates that all active references on
vfio_device have been released.
After that point although free of vfio_ccw_private is delayed to
css_driver it's at least guaranteed to have no parallel reference on
released vfio device part from other code paths.
memset() in @probe is removed. vfio_device is either alreary cleared
when probed for the first time or cleared in @release from last probe.
The right fix is to introduce separate structures for mdev and parent,
but this won't happen in short term per prior discussions.
Remove vfio_init/uninit_group_dev() as no user now.
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
---
drivers/s390/cio/vfio_ccw_ops.c | 52 +++++++++++++++++++++++++----
drivers/s390/cio/vfio_ccw_private.h | 3 ++
drivers/vfio/vfio_main.c | 27 +++------------
include/linux/vfio.h | 3 --
4 files changed, 53 insertions(+), 32 deletions(-)
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 4a806a2273b5..9f8486c0d3d3 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -87,6 +87,15 @@ static struct attribute_group *mdev_type_groups[] = {
NULL,
};
+static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev)
+{
+ struct vfio_ccw_private *private =
+ container_of(vdev, struct vfio_ccw_private, vdev);
+
+ init_completion(&private->release_comp);
+ return 0;
+}
+
static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
{
struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent);
@@ -98,9 +107,9 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
if (atomic_dec_if_positive(&private->avail) < 0)
return -EPERM;
- memset(&private->vdev, 0, sizeof(private->vdev));
- vfio_init_group_dev(&private->vdev, &mdev->dev,
- &vfio_ccw_dev_ops);
+ ret = vfio_init_device(&private->vdev, &mdev->dev, &vfio_ccw_dev_ops);
+ if (ret)
+ return ret;
VFIO_CCW_MSG_EVENT(2, "sch %x.%x.%04x: create\n",
private->sch->schid.cssid,
@@ -109,16 +118,33 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev)
ret = vfio_register_emulated_iommu_dev(&private->vdev);
if (ret)
- goto err_atomic;
+ goto err_put_vdev;
dev_set_drvdata(&mdev->dev, private);
return 0;
-err_atomic:
- vfio_uninit_group_dev(&private->vdev);
+err_put_vdev:
+ vfio_put_device(&private->vdev);
atomic_inc(&private->avail);
return ret;
}
+static void vfio_ccw_mdev_release_dev(struct vfio_device *vdev)
+{
+ struct vfio_ccw_private *private =
+ container_of(vdev, struct vfio_ccw_private, vdev);
+
+ /*
+ * We cannot free vfio_ccw_private here because it includes
+ * parent info which must be free'ed by css driver.
+ *
+ * Use a workaround by memset'ing the core device part and
+ * then notifying the remove path that all active references
+ * to this device have been released.
+ */
+ memset(vdev, 0, sizeof(*vdev));
+ complete(&private->release_comp);
+}
+
static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
{
struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent);
@@ -130,7 +156,17 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev)
vfio_unregister_group_dev(&private->vdev);
- vfio_uninit_group_dev(&private->vdev);
+ vfio_put_device(&private->vdev);
+ /*
+ * Wait for all active references on mdev are released so it
+ * is safe to defer kfree() to a later point.
+ *
+ * TODO: the clean fix is to split parent/mdev info from ccw
+ * private structure so each can be managed in its own life
+ * cycle.
+ */
+ wait_for_completion(&private->release_comp);
+
atomic_inc(&private->avail);
}
@@ -592,6 +628,8 @@ static void vfio_ccw_mdev_request(struct vfio_device *vdev, unsigned int count)
}
static const struct vfio_device_ops vfio_ccw_dev_ops = {
+ .init = vfio_ccw_mdev_init_dev,
+ .release = vfio_ccw_mdev_release_dev,
.open_device = vfio_ccw_mdev_open_device,
.close_device = vfio_ccw_mdev_close_device,
.read = vfio_ccw_mdev_read,
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index cd24b7fada91..63d9202b29c7 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -88,6 +88,7 @@ struct vfio_ccw_crw {
* @req_trigger: eventfd ctx for signaling userspace to return device
* @io_work: work for deferral process of I/O handling
* @crw_work: work for deferral process of CRW handling
+ * @release_comp: synchronization helper for vfio device release
*/
struct vfio_ccw_private {
struct vfio_device vdev;
@@ -113,6 +114,8 @@ struct vfio_ccw_private {
struct eventfd_ctx *req_trigger;
struct work_struct io_work;
struct work_struct crw_work;
+
+ struct completion release_comp;
} __aligned(8);
int vfio_ccw_sch_quiesce(struct subchannel *sch);
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 9485da17f2e6..15a612153c13 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -482,21 +482,6 @@ static struct vfio_device *vfio_group_get_device(struct vfio_group *group,
/*
* VFIO driver API
*/
-void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
- const struct vfio_device_ops *ops)
-{
- init_completion(&device->comp);
- device->dev = dev;
- device->ops = ops;
-}
-EXPORT_SYMBOL_GPL(vfio_init_group_dev);
-
-void vfio_uninit_group_dev(struct vfio_device *device)
-{
- vfio_release_device_set(device);
-}
-EXPORT_SYMBOL_GPL(vfio_uninit_group_dev);
-
/*
* Alloc and initialize vfio_device so it can be registered to vfio
* core.
@@ -543,20 +528,18 @@ int vfio_init_device(struct vfio_device *device, struct device *dev,
{
int ret;
- vfio_init_group_dev(device, dev, ops);
+ init_completion(&device->comp);
+ device->dev = dev;
+ device->ops = ops;
if (ops->init) {
ret = ops->init(device);
if (ret)
- goto out_uninit;
+ return ret;
}
kref_init(&device->kref);
return 0;
-
-out_uninit:
- vfio_uninit_group_dev(device);
- return ret;
}
EXPORT_SYMBOL_GPL(vfio_init_device);
@@ -577,7 +560,7 @@ void vfio_device_release(struct kref *kref)
struct vfio_device *device =
container_of(kref, struct vfio_device, kref);
- vfio_uninit_group_dev(device);
+ vfio_release_device_set(device);
/*
* kvfree() cannot be done here due to a life cycle mess in
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index b0928a81b45a..a36a65b966b5 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -160,9 +160,6 @@ static inline void vfio_put_device(struct vfio_device *device)
kref_put(&device->kref, vfio_device_release);
}
-void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
- const struct vfio_device_ops *ops);
-void vfio_uninit_group_dev(struct vfio_device *device);
int vfio_register_group_dev(struct vfio_device *device);
int vfio_register_emulated_iommu_dev(struct vfio_device *device);
void vfio_unregister_group_dev(struct vfio_device *device);
--
2.21.3
next prev parent reply other threads:[~2022-08-27 9:52 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-27 17:10 [PATCH 00/15] Tidy up vfio_device life cycle Kevin Tian
2022-08-27 17:10 ` [PATCH 01/15] vfio: Add helpers for unifying " Kevin Tian
2022-08-30 13:42 ` Anthony Krowiak
2022-08-30 15:10 ` Jason Gunthorpe
2022-08-30 19:43 ` Anthony Krowiak
2022-08-31 6:03 ` Tian, Kevin
2022-08-27 17:10 ` [PATCH 02/15] vfio/pci: Use the new device life cycle helpers Kevin Tian
2022-08-27 17:10 ` [PATCH 03/15] vfio/mlx5: " Kevin Tian
2022-08-27 17:10 ` [PATCH 04/15] vfio/hisi_acc: " Kevin Tian
2022-08-31 7:36 ` Shameerali Kolothum Thodi
2022-08-27 17:10 ` [PATCH 05/15] vfio/mdpy: " Kevin Tian
2022-08-27 17:10 ` [PATCH 06/15] vfio/mtty: " Kevin Tian
2022-08-27 17:10 ` [PATCH 07/15] vfio/mbochs: " Kevin Tian
2022-08-27 17:10 ` [PATCH 08/15] drm/i915/gvt: " Kevin Tian
2022-08-27 17:10 ` [PATCH 09/15] vfio/ap: " Kevin Tian
2022-08-30 13:43 ` Anthony Krowiak
2022-08-27 17:10 ` [PATCH 10/15] vfio/fsl-mc: " Kevin Tian
2022-08-31 0:22 ` Jason Gunthorpe
2022-08-31 6:14 ` Tian, Kevin
2022-08-27 17:10 ` [PATCH 11/15] vfio/platform: " Kevin Tian
2022-08-27 17:10 ` [PATCH 12/15] vfio/amba: " Kevin Tian
2022-08-27 17:10 ` Kevin Tian [this message]
2022-08-27 10:39 ` [PATCH 13/15] vfio/ccw: " Tian, Kevin
2022-08-27 17:10 ` [PATCH 14/15] vfio: Rename vfio_device_put() and vfio_device_try_get() Kevin Tian
2022-08-27 17:10 ` [PATCH 15/15] vfio: Add struct device to vfio_device Kevin Tian
2022-08-30 22:18 ` Alex Williamson
2022-08-30 23:53 ` Jason Gunthorpe
2022-08-31 6:10 ` Tian, Kevin
2022-08-31 17:15 ` Alex Williamson
2022-09-01 0:46 ` Tian, Kevin
2022-09-01 2:05 ` Alex Williamson
2022-08-31 0:32 ` Jason Gunthorpe
2022-08-31 6:14 ` Tian, Kevin
2022-08-27 22:41 ` [PATCH 00/15] Tidy up vfio_device life cycle Tian, Kevin
2022-08-31 0:34 ` Jason Gunthorpe
2022-08-31 6:14 ` Tian, Kevin
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