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authorEric Farman <farman@linux.ibm.com>2020-12-04 00:35:11 +0300
committerAlex Williamson <alex.williamson@redhat.com>2020-12-04 02:21:07 +0300
commita15ac665b9e9c90b1557499f2a46c1e89d29154a (patch)
tree0ed3f9dd8ceebb126437a992bad4fc8144838f2b /include/linux/mdev.h
parentd22f9a6c92de96304c81792942ae7c306f08ac77 (diff)
downloadlinux-a15ac665b9e9c90b1557499f2a46c1e89d29154a.tar.xz
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 'include/linux/mdev.h')
-rw-r--r--include/linux/mdev.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 0ce30ca78db0..9004375c462e 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -72,6 +72,9 @@ struct device *mdev_get_iommu_device(struct device *dev);
* @mmap: mmap callback
* @mdev: mediated device structure
* @vma: vma structure
+ * @request: request callback to release device
+ * @mdev: mediated device structure
+ * @count: request sequence number
* Parent device that support mediated device should be registered with mdev
* module with mdev_parent_ops structure.
**/
@@ -92,6 +95,7 @@ struct mdev_parent_ops {
long (*ioctl)(struct mdev_device *mdev, unsigned int cmd,
unsigned long arg);
int (*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma);
+ void (*request)(struct mdev_device *mdev, unsigned int count);
};
/* interface for exporting mdev supported type attributes */