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| author | Eric Farman <farman@linux.ibm.com> | 2020-12-03 22:35:11 +0100 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2020-12-03 16:21:07 -0700 |
| commit | a15ac665b9e9c90b1557499f2a46c1e89d29154a (patch) | |
| tree | 0ed3f9dd8ceebb126437a992bad4fc8144838f2b /drivers/vfio | |
| parent | d22f9a6c92de96304c81792942ae7c306f08ac77 (diff) | |
| download | linux-a15ac665b9e9c90b1557499f2a46c1e89d29154a.tar.bz2 | |
vfio-mdev: Wire in a request handler for mdev parent
While performing some destructive tests with vfio-ccw, where the
paths to a device are forcible removed and thus the device itself
is unreachable, it is rather easy to end up in an endless loop in
vfio_del_group_dev() due to the lack of a request callback for the
associated device.
In this example, one MDEV (77c) is used by a guest, while another
(77b) is not. The symptom is that the iommu is detached from the
mdev for 77b, but not 77c, until that guest is shutdown:
[ 238.794867] vfio_ccw 0.0.077b: MDEV: Unregistering
[ 238.794996] vfio_mdev 11f2d2bc-4083-431d-a023-eff72715c4f0: Removing from iommu group 2
[ 238.795001] vfio_mdev 11f2d2bc-4083-431d-a023-eff72715c4f0: MDEV: detaching iommu
[ 238.795036] vfio_ccw 0.0.077c: MDEV: Unregistering
...silence...
Let's wire in the request call back to the mdev device, so that a
device being physically removed from the host can be (gracefully?)
handled by the parent device at the time the device is removed.
Add a message when registering the device if a driver doesn't
provide this callback, so a clue is given that this same loop
may be encountered in a similar situation, and a message when
this occurs instead of the awkward silence noted above.
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
| -rw-r--r-- | drivers/vfio/mdev/mdev_core.c | 4 | ||||
| -rw-r--r-- | drivers/vfio/mdev/vfio_mdev.c | 13 |
2 files changed, 17 insertions, 0 deletions
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c index b558d4cfd082..6de97d25a3f8 100644 --- a/drivers/vfio/mdev/mdev_core.c +++ b/drivers/vfio/mdev/mdev_core.c @@ -154,6 +154,10 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) if (!dev) return -EINVAL; + /* Not mandatory, but its absence could be a problem */ + if (!ops->request) + dev_info(dev, "Driver cannot be asked to release device\n"); + mutex_lock(&parent_list_lock); /* Check for duplicate */ diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c index 30964a4e0a28..b52eea128549 100644 --- a/drivers/vfio/mdev/vfio_mdev.c +++ b/drivers/vfio/mdev/vfio_mdev.c @@ -98,6 +98,18 @@ static int vfio_mdev_mmap(void *device_data, struct vm_area_struct *vma) return parent->ops->mmap(mdev, vma); } +static void vfio_mdev_request(void *device_data, unsigned int count) +{ + struct mdev_device *mdev = device_data; + struct mdev_parent *parent = mdev->parent; + + if (parent->ops->request) + parent->ops->request(mdev, count); + else if (count == 0) + dev_notice(mdev_dev(mdev), + "No mdev vendor driver request callback support, blocked until released by user\n"); +} + static const struct vfio_device_ops vfio_mdev_dev_ops = { .name = "vfio-mdev", .open = vfio_mdev_open, @@ -106,6 +118,7 @@ static const struct vfio_device_ops vfio_mdev_dev_ops = { .read = vfio_mdev_read, .write = vfio_mdev_write, .mmap = vfio_mdev_mmap, + .request = vfio_mdev_request, }; static int vfio_mdev_probe(struct device *dev) |