Devices may have component devices and buses.
Device realization may fail. Realization is recursive: a device's
realize() method realizes its components, and device_set_realized()
realizes its buses (which should in turn realize the devices on that
bus, except bus_set_realized() doesn't implement that, yet).
When realization of a component or bus fails, we need to roll back:
unrealize everything we realized so far. If any of these unrealizes
failed, the device would be left in an inconsistent state. Must not
happen.
device_set_realized() lets it happen: it ignores errors in the roll
back code starting at label child_realize_fail.
Since realization is recursive, unrealization must be recursive, too.
But how could a partly failed unrealize be rolled back? We'd have to
re-realize, which can fail. This design is fundamentally broken.
device_set_realized() does not roll back at all. Instead, it keeps
unrealizing, ignoring further errors.
It can screw up even for a device with no buses: if the lone
dc->unrealize() fails, it still unregisters vmstate, and calls
listeners' unrealize() callback.
bus_set_realized() does not roll back either. Instead, it stops
unrealizing.
Fortunately, no unrealize method can fail, as we'll see below.
To fix the design error, drop parameter @errp from all the unrealize
methods.
Any unrealize method that uses @errp now needs an update. This leads
us to unrealize() methods that can fail. Merely passing it to another
unrealize method cannot cause failure, though. Here are the ones that
do other things with @errp:
* virtio_serial_device_unrealize()
Fails when qbus_set_hotplug_handler() fails, but still does all the
other work. On failure, the device would stay realized with its
resources completely gone. Oops. Can't happen, because
qbus_set_hotplug_handler() can't actually fail here. Pass
&error_abort to qbus_set_hotplug_handler() instead.
* hw/ppc/spapr_drc.c's unrealize()
Fails when object_property_del() fails, but all the other work is
already done. On failure, the device would stay realized with its
vmstate registration gone. Oops. Can't happen, because
object_property_del() can't actually fail here. Pass &error_abort
to object_property_del() instead.
* spapr_phb_unrealize()
Fails and bails out when remove_drcs() fails, but other work is
already done. On failure, the device would stay realized with some
of its resources gone. Oops. remove_drcs() fails only when
chassis_from_bus()'s object_property_get_uint() fails, and it can't
here. Pass &error_abort to remove_drcs() instead.
Therefore, no unrealize method can fail before this patch.
device_set_realized()'s recursive unrealization via bus uses
object_property_set_bool(). Can't drop @errp there, so pass
&error_abort.
We similarly unrealize with object_property_set_bool() elsewhere,
always ignoring errors. Pass &error_abort instead.
Several unrealize methods no longer handle errors from other unrealize
methods: virtio_9p_device_unrealize(),
virtio_input_device_unrealize(), scsi_qdev_unrealize(), ...
Much of the deleted error handling looks wrong anyway.
One unrealize methods no longer ignore such errors:
usb_ehci_pci_exit().
Several realize methods no longer ignore errors when rolling back:
v9fs_device_realize_common(), pci_qdev_unrealize(),
spapr_phb_realize(), usb_qdev_realize(), vfio_ccw_realize(),
virtio_device_realize().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-17-armbru@redhat.com>
Since 7f5d9b206d ("object-add: don't create return value if
failed"), qmp_object_add() don't write any value in 'ret_data', thus
has random data. Then qobject_unref() fails and abort().
Fix by initialising 'ret_data' properly.
Fixes: 5f07c4d60d ("qapi: Flatten object-add")
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200406164207.1446817-1-anthony.perard@citrix.com>
While there, tidy up indentation, and add return just for consistency
and robustness.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200313170517.22480-4-armbru@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[The "while there" cleanups squashed in]
Mapping object-add to the command line as is doesn't result in nice
syntax because of the nesting introduced with 'props'. This becomes
nicer and more consistent with device_add and netdev_add when we accept
properties for the object on the top level instead.
'props' is still accepted after this patch, but marked as deprecated.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-8-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When a frontend gracefully disconnects from an offline backend, it will
set its own state to XenbusStateClosed. The code in xen-block.c correctly
deals with this and sets the backend into XenbusStateClosed. Unfortunately
it is possible for toolstack to actually delete the frontend area
before the state key has been read, leading to an apparent frontend state
of XenbusStateUnknown. This prevents the backend state from transitioning
to XenbusStateClosed and hence leaves it limbo.
This patch simply treats a frontend state of XenbusStateUnknown the same
as XenbusStateClosed, which will unblock the backend in these circumstances.
Reported-by: Mark Syms <mark.syms@citrix.com>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-Id: <20190918115702.38959-1-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
In my "build everything" tree, changing hw/qdev-properties.h triggers
a recompile of some 2700 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h).
Many places including hw/qdev-properties.h (directly or via hw/qdev.h)
actually need only hw/qdev-core.h. Include hw/qdev-core.h there
instead.
hw/qdev.h is actually pointless: all it does is include hw/qdev-core.h
and hw/qdev-properties.h, which in turn includes hw/qdev-core.h.
Replace the remaining uses of hw/qdev.h by hw/qdev-properties.h.
While there, delete a few superfluous inclusions of hw/qdev-core.h.
Touching hw/qdev-properties.h now recompiles some 1200 objects.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190812052359.30071-22-armbru@redhat.com>
In my "build everything" tree, changing qemu/main-loop.h triggers a
recompile of some 5600 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h). It includes block/aio.h,
which in turn includes qemu/event_notifier.h, qemu/notify.h,
qemu/processor.h, qemu/qsp.h, qemu/queue.h, qemu/thread-posix.h,
qemu/thread.h, qemu/timer.h, and a few more.
Include qemu/main-loop.h only where it's needed. Touching it now
recompiles only some 1700 objects. For block/aio.h and
qemu/event_notifier.h, these numbers drop from 5600 to 2800. For the
others, they shrink only slightly.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190812052359.30071-21-armbru@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
In my "build everything" tree, changing hw/hw.h triggers a recompile
of some 2600 out of 6600 objects (not counting tests and objects that
don't depend on qemu/osdep.h).
The previous commits have left only the declaration of hw_error() in
hw/hw.h. This permits dropping most of its inclusions. Touching it
now recompiles less than 200 objects.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-19-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Move commands object-add, object-del, qom-get, qom-list,
qom-list-properties, qom-list-types, and qom-set with their types from
misc.json to new qom.json.
Move commands device-list-properties, device_add, device-del, and
event DEVICE_DELETED from misc.json to new qdev.json.
Add both new files to MAINTAINERS section QOM.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190619201050.19040-5-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[Straightforwardly updated for "MAINTAINERS: Make section "QOM" cover
qdev as well"]
A recent Xen commit [1] clarified the semantics of sector based quantities
used in the blkif protocol such that it is now safe to create a xen-block
device with a logical_block_size != 512, as long as the device only
connects to a frontend advertizing 'feature-large-block-size'.
This patch modifies xen-block accordingly. It also uses a stack variable
for the BlockBackend in xen_block_realize() to avoid repeated dereferencing
of the BlockConf pointer, and changes the parameters of
xen_block_dataplane_create() so that the BlockBackend pointer and sector
size are passed expicitly rather than implicitly via the BlockConf.
These modifications have been tested against a recent Windows PV XENVBD
driver [2] using a xen-disk device with a 4kB logical block size.
[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=67e1c050e36b2c9900cca83618e56189effbad98
[2] https://winpvdrvbuild.xenproject.org:8080/job/XENVBD-master/126
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190409164038.25484-1-paul.durrant@citrix.com>
[Edited error message]
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
This adds a new parameter to blk_new() which requires its callers to
declare from which AioContext this BlockBackend is going to be used (or
the locks of which AioContext need to be taken anyway).
The given context is only stored and kept up to date when changing
AioContexts. Actually applying the stored AioContext to the root node
is saved for another commit.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The Xen blkif protocol requires that sector based quantities should be
interpreted strictly as multiples of 512 bytes. Specifically:
"first_sect and last_sect in blkif_request_segment, as well as
sector_number in blkif_request, are always expressed in 512-byte units."
Commit fcab2b464e "xen: add header and build dataplane/xen-block.c"
incorrectly modified behaviour to use the block device logical_block_size
property as the scale, instead of correctly shifting values by the
hardcoded BDRV_SECTOR_BITS (and hence scaling them to 512 byte units).
This patch undoes that change and restores compliance with the spec.
Furthermore, this patch also restores the original xen_disk behaviour
of advertizing a hardcoded 'sector-size' value of 512 in xenstore and
scaling 'sectors' accordingly. The realize() method is also modified to
fail if logical_block_size is set to anything other than 512.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190401121719.27208-1-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
...and properly enable it when synthesizing a drive.
The Xen toolstack sets 'discard-enable' to '1' in xenstore when it wants
to enable discard on a specified image. The code in
xen_block_drive_create() correctly parses this and uses it to set
'discard' to 'unmap' for the file_layer, but fails to do the same for the
driver_layer (which effectively disables it). Meanwhile the code in
xen_block_realize() advertizes discard support to the frontend in the
default case (because conf->discard_granularity defaults to -1), even when
the underlying image may not handle it.
This patch adds the missing option to the driver_layer in
xen_block_driver_create() and checks whether BDRV_O_UNMAP is actually
set on the block device before advertizing discard to the frontend.
In the case that discard is supported it also makes sure that the
granularity is set to the physical block size.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190320142825.24565-1-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Patch created mechanically by rerunning:
$ spatch --sp-file scripts/coccinelle/qobject.cocci \
--macro-file scripts/cocci-macro-file.h \
--dir hw/block --in-place
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190313174433.12966-1-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
The locally allocated QDict-s need to be freed. ('file_layer' will be
freed implicitly since it is added as an object to 'driver_layer').
Spotted by Coverity: CID 1398649
While in the neighbourhood free 'driver' and 'filename' as soon as they are
added to the QDicts. Freeing after the 'done' label doesn't make that much
sense as, if the error path jumps to that label, the values would be NULL
anyway.
This patch also makes that more obvious by taking the error path if
'params' is NULL and then asserting that both driver and filename are
non-NULL in the normal path.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Message-Id: <20190219163440.15702-1-paul.durrant@citrix.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
The function needs to make sure it is passed a valid disk name. This is
easily done by making sure that the parsing loop results in a non-zero
value.
Spotted by Coverity: CID 1398640
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190215162533.19475-4-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
The assignment to 'p' is unnecessary as the code will either goto 'invalid'
or p will get overwritten.
Spotted by Coverity: CID 1398638
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20190215162533.19475-3-paul.durrant@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Some frontend drivers will handle dynamic resizing of PV disks, so set up
the BlockDevOps resize_cb() method during xen_block_realize() to allow
this to be done.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
The %lu format string is different depending on the host architecture
which causes builds like the debian-armhf-cross build to fail. Use the
correct PRi64 format string.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190116121350.23863-1-alex.bennee@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This patch adds create and destroy function for XenBlockDevice-s so that
they can be created automatically when the Xen toolstack instantiates a new
PV backend via xenstore. When the XenBlockDevice is created this way it is
also necessary to create a 'drive' which matches the configuration that the
Xen toolstack has written into xenstore. This is done by formulating the
parameters necessary for each 'blockdev' layer of the drive and then using
qmp_blockdev_add() to create the layers. Also, for compatibility with the
legacy 'xen_disk' implementation, an iothread is automatically created for
the new XenBlockDevice. This, like the driver layers, will be destroyed
after the XenBlockDevice is unrealized.
The legacy backend scan for 'qdisk' is removed by this patch, which makes
the 'xen_disk' code is redundant. The code will be removed by a subsequent
patch.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
...and wire in the dataplane.
This patch adds the remaining code to make the xen-block XenDevice
functional. The parameters that a block frontend expects to find are
populated in the backend xenstore area, and the 'ring-ref' and
'event-channel' values specified in the frontend xenstore area are
mapped/bound and used to set up the dataplane.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
A Xen PV frontend communicates its state to the PV backend by writing to
the 'state' key in the frontend area in xenstore. It is therefore
necessary for a XenDevice implementation to be notified whenever the
value of this key changes.
This patch adds code to do this as follows:
- an 'fd handler' is registered on the libxenstore handle which will be
triggered whenever a 'watch' event occurs
- primitives are added to xen-bus-helper to add or remove watch events
- a list of Notifier objects is added to XenBus to provide a mechanism
to call the appropriate 'watch handler' when its associated event
occurs
The xen-block implementation is extended with a 'frontend_changed' method,
which calls as-yet stub 'connect' and 'disconnect' functions when the
relevant frontend state transitions occur. A subsequent patch will supply
a full implementation for these functions.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
This patch adds a new source module, xen-bus-helper.c, which builds on
basic libxenstore primitives to provide functions to create (setting
permissions appropriately) and destroy xenstore areas, and functions to
'printf' and 'scanf' nodes therein. The main xen-bus code then uses
these primitives [1] to initialize and destroy the frontend and backend
areas for a XenDevice during realize and unrealize respectively.
The 'xen-block' implementation is extended with a 'get_name' method that
returns the VBD number. This number is required to 'name' the xenstore
areas.
NOTE: An exit handler is also added to make sure the xenstore areas are
cleaned up if QEMU terminates without devices being unrealized.
[1] The 'scanf' functions are actually not yet needed, but they will be
needed by code delivered in subsequent patches.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
This patch adds new XenDevice-s: 'xen-disk' and 'xen-cdrom', both derived
from a common 'xen-block' parent type. These will eventually replace the
'xen_disk' (note the underscore rather than hyphen) legacy PV backend but
it is illustrative to build up the implementation incrementally, along with
the XenBus/XenDevice framework. Subsequent patches will therefore add to
these devices' implementation as new features are added to the framework.
After this patch has been applied it is possible to instantiate new
'xen-disk' or 'xen-cdrom' devices with a single 'vdev' parameter, which
accepts values adhering to the Xen VBD naming scheme [1]. For example, a
command-line instantiation of a xen-disk can be done with an argument
similar to the following:
-device xen-disk,vdev=hda
The implementation of the vdev parameter formulates the appropriate VBD
number for use in the PV protocol.
[1] https://xenbits.xen.org/docs/unstable/man/xen-vbd-interface.7.html
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
