| f7b879e0 | 16-Oct-2017 |
Michael Roth <mdroth@linux.vnet.ibm.com> |
qdev: defer DEVICE_DEL event until instance_finalize()
DEVICE_DEL is currently emitted when a Device is unparented, as
opposed to when it is finalized. The main design motivation for this
seems to b
qdev: defer DEVICE_DEL event until instance_finalize()
DEVICE_DEL is currently emitted when a Device is unparented, as
opposed to when it is finalized. The main design motivation for this
seems to be that after unparent()/unrealize(), the Device is no
longer visible to the guest, and thus the operation is complete
from the perspective of management.
However, there are cases where remaining host-side cleanup is also
pertinent to management. The is generally handled by treating these
resources as aspects of the "backend", which can be managed via
separate interfaces/events, such as blockdev_add/del, netdev_add/del,
object_add/del, etc, but some devices do not have this level of
compartmentalization, namely vfio-pci, and possibly to lend themselves
well to it.
In the case of vfio-pci, the "backend" cleanup happens as part of
the finalization of the vfio-pci device itself, in particular the
cleanup of the VFIO group FD. Failing to wait for this cleanup can
result in tools like libvirt attempting to rebind the device to
the host while it's still being used by VFIO, which can result in
host crashes or other misbehavior depending on the host driver.
Deferring DEVICE_DEL still affords us the ability to manage backends
explicitly, while also addressing cases like vfio-pci's, so we
implement that approach here.
An alternative proposal involving having VFIO emit a separate event
to denote completion of host-side cleanup was discussed, but the
prevailing opinion seems to be that it is not worth the added
complexity, and leaves the issue open for other Device implementations
to solve in the future.
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20171016222315.407-4-mdroth@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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| 2fc06c4a | 16-Oct-2017 |
Michael Roth <mdroth@linux.vnet.ibm.com> |
Revert "qdev: Free QemuOpts when the QOM path goes away"
This reverts commit abed886ec60cf239a03515cf0b30fb11fa964c44.
This patch originally addressed an issue where a DEVICE_DELETED
event could be
Revert "qdev: Free QemuOpts when the QOM path goes away"
This reverts commit abed886ec60cf239a03515cf0b30fb11fa964c44.
This patch originally addressed an issue where a DEVICE_DELETED
event could be emitted (in device_unparent()) before a Device's
QemuOpts were cleaned up (in device_finalize()), leading to a
"duplicate ID" error if management attempted to immediately add
a device with the same ID in response to the DEVICE_DELETED event.
An alternative will be implemented in a subsequent patch where we
defer the DEVICE_DELETED event until device_finalize(), which would
also prevent the race, so we revert the original fix in preparation.
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20171016222315.407-3-mdroth@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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| 04162f8f | 16-Oct-2017 |
Michael Roth <mdroth@linux.vnet.ibm.com> |
qdev: store DeviceState's canonical path to use when unparenting
device_unparent(dev, ...) is called when a device is unparented,
either directly, or as a result of a parent device being
finalized,
qdev: store DeviceState's canonical path to use when unparenting
device_unparent(dev, ...) is called when a device is unparented,
either directly, or as a result of a parent device being
finalized, and handles some final cleanup for the device. Part
of this includes emiting a DEVICE_DELETED QMP event to notify
management, which includes the device's path in the composition
tree as provided by object_get_canonical_path().
object_get_canonical_path() assumes the device is still connected
to the machine/root container, and will assert otherwise, but
in some situations this isn't the case:
If the parent is finalized as a result of object_unparent(), it
will still be attached to the composition tree at the time any
children are unparented as a result of that same call to
object_unparent(). However, in some cases, object_unparent()
will complete without finalizing the parent device, due to
lingering references that won't be released till some time later.
One such example is if the parent has MemoryRegion children (which
take a ref on their parent), who in turn have AddressSpace's (which
take a ref on their regions), since those AddressSpaces get cleaned
up asynchronously by the RCU thread.
In this case qdev:device_unparent() may be called for a child Device
that no longer has a path to the root/machine container, causing
object_get_canonical_path() to assert.
Fix this by storing the canonical path during realize() so the
information will still be available for device_unparent() in such
cases.
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20171016222315.407-2-mdroth@linux.vnet.ibm.com>
[Clear dev->canonical_path at the post_realize_fail label, which is
cleaner. Suggested by David Gibson. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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| 6d1e30c4 | 10-Jul-2017 |
Eduardo Habkost <ehabkost@redhat.com> |
Revert "machine: Convert abstract typename on compat_props to subclass names"
This reverts commit 0bcba41fe379e4c6834adcf1456d9099db31a5b2.
The bug addressed by that commit is now fixed in a better
Revert "machine: Convert abstract typename on compat_props to subclass names"
This reverts commit 0bcba41fe379e4c6834adcf1456d9099db31a5b2.
The bug addressed by that commit is now fixed in a better way by the
commit "qdev: fix the order compat and global properties are applied".
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170711004303.3902-4-ehabkost@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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