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* xen: perform XenDevice clean-up in XenBus watch handlerPaul Durrant2019-09-241-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Cleaning up offline XenDevice objects directly in xen_device_backend_changed() is dangerous as xen_device_unrealize() will modify the watch list that is being walked. Even the QLIST_FOREACH_SAFE() used in notifier_list_notify() is insufficient as *two* notifiers (for the frontend and backend watches) are removed, thus potentially rendering the 'next' pointer unsafe. The solution is to use the XenBus backend_watch handler to do the clean-up instead, as it is invoked whilst walking a separate watch list. This patch therefore adds a new 'inactive_devices' list to XenBus, to which offline devices are added by xen_device_backend_changed(). The XenBus backend_watch registration is also changed to not only invoke xen_bus_enumerate() but also a new xen_bus_cleanup() function, which will walk 'inactive_devices' and perform the necessary actions. For safety an extra 'online' check is also added to xen_bus_type_enumerate() to make sure that no attempt is made to create a new XenDevice object for a backend that is offline. NOTE: This patch also includes some cosmetic changes: - substitute the local variable name 'backend_state' in xen_bus_type_enumerate() with 'state', since there is no ambiguity with any other state in that context. - change xen_device_state_is_active() to xen_device_frontend_is_active() (and pass a XenDevice directly) since the state tests contained therein only apply to a frontend. - use 'state' rather then 'xendev->backend_state' in xen_device_backend_changed() to shorten the code. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Anthony PERARD <anthony.perard@citrix.com> Message-Id: <20190913082159.31338-4-paul.durrant@citrix.com> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
* xen: introduce separate XenWatchList for XenDevice objectsPaul Durrant2019-09-241-0/+2
| | | | | | | | | | | | This patch uses the XenWatchList abstraction to add a separate watch list for each device. This is more scalable than walking a single notifier list for all watches and is also necessary to implement a bug-fix in a subsequent patch. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Anthony Perard <anthony.perard@citrix.com> Message-Id: <20190913082159.31338-3-paul.durrant@citrix.com> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
* xen / notify: introduce a new XenWatchList abstractionPaul Durrant2019-09-241-3/+2Star
| | | | | | | | | | | | | | | | | | | | Xenstore watch call-backs are already abstracted away from XenBus using the XenWatch data structure but the associated NotifierList manipulation and file handle registration is still open coded in various xen_bus_...() functions. This patch creates a new XenWatchList data structure to allow these interactions to be abstracted away from XenBus as well. This is in preparation for a subsequent patch which will introduce separate watch lists for XenBus and XenDevice objects. NOTE: This patch also introduces a new notifier_list_empty() helper function for the purposes of adding an assertion that a XenWatchList is not freed whilst its associated NotifierList is still occupied. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Anthony Perard <anthony.perard@citrix.com> Message-Id: <20190913082159.31338-2-paul.durrant@citrix.com> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
* trace-events: Shorten file names in commentsMarkus Armbruster2019-03-221-3/+3
| | | | | | | | | | | | | | | We spell out sub/dir/ in sub/dir/trace-events' comments pointing to source files. That's because when trace-events got split up, the comments were moved verbatim. Delete the sub/dir/ part from these comments. Gets rid of several misspellings. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20190314180929.27722-3-armbru@redhat.com Message-Id: <20190314180929.27722-3-armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* xen: add a mechanism to automatically create XenDevice-s...Paul Durrant2019-01-141-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | ...that maintains compatibility with existing Xen toolstacks. Xen toolstacks instantiate PV backends by simply writing information into xenstore and expecting a backend implementation to be watching for this. This patch adds a new 'xen-backend' module to allow individual XenDevice implementations to register create and destroy functions. The creator will be called when a tool-stack instantiates a new backend in this way, and the destructor will then be called after the resulting XenDevice object is unrealized. To support this it is also necessary to add new watchers into the XenBus implementation to handle enumeration of new backends and also destruction of XenDevice-s when the toolstack sets the backend 'online' key to 0. NOTE: This patch only adds the framework. A subsequent patch will add a creator function for xen-block devices. 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>
* xen: add implementations of xen-block connect and disconnect functions...Paul Durrant2019-01-141-0/+3
| | | | | | | | | | | | | | ...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>
* xen: add xenstore watcher infrastructurePaul Durrant2019-01-141-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | 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>
* xen: create xenstore areas for XenDevice-sPaul Durrant2019-01-141-2/+10
| | | | | | | | | | | | | | | | | | | | | | | 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>
* xen: introduce new 'XenBus' and 'XenDevice' object hierarchyPaul Durrant2019-01-141-0/+6
| | | | | | | | | | | | | | | This patch adds the basic boilerplate for a 'XenBus' object that will act as a parent to 'XenDevice' PV backends. A new 'XenBridge' object is also added to connect XenBus to the system bus. The XenBus object is instantiated by a new xen_bus_init() function called from the same sites as the legacy xen_be_init() function. Subsequent patches will flesh-out the functionality of these objects. 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>
* trace-events: fix code style: %# -> 0x%Vladimir Sementsov-Ogievskiy2017-08-011-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In trace format '#' flag of printf is forbidden. Fix it to '0x%'. This patch is created by the following: check that we have a problem > find . -name trace-events | xargs grep '%#' | wc -l 56 check that there are no cases with additional printf flags before '#' > find . -name trace-events | xargs grep "%[-+ 0'I]+#" | wc -l 0 check that there are no wrong usage of '#' and '0x' together > find . -name trace-events | xargs grep '0x%#' | wc -l 0 fix the problem > find . -name trace-events | xargs sed -i 's/%#/0x%/g' [Eric Blake noted that xargs grep '%[-+ 0'I]+#' should be xargs grep "%[-+ 0'I]+#" instead so the shell quoting is correct. --Stefan] Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 20170731160135.12101-3-vsementsov@virtuozzo.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
* docs: fix broken paths to docs/devel/tracing.txtPhilippe Mathieu-Daudé2017-07-311-1/+1
| | | | | | | | | With the move of some docs/ to docs/devel/ on ac06724a71, no references were updated. Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
* xen: use libxendevice model to restrict operationsPaul Durrant2017-04-211-0/+1
| | | | | | | | | | | | | | | | | This patch adds a command-line option (-xen-domid-restrict) which will use the new libxendevicemodel API to restrict devicemodel [1] operations to the specified domid. (Such operations are not applicable to the xenpv machine type). This patch also adds a tracepoint to allow successful enabling of the restriction to be monitored. [1] I.e. operations issued by libxendevicemodel. Operation issued by other xen libraries (e.g. libxenforeignmemory) are currently still unrestricted but this will be rectified by subsequent patches. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
* trace: move hw/xen events to correct subdirDaniel P. Berrange2017-01-311-0/+13
The trace-events for a given source file should generally always live in the same directory as the source file. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170125161417.31949-4-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>