#============================================================================ # This library is free software; you can redistribute it and/or # modify it under the terms of version 2.1 of the GNU Lesser General Public # License as published by the Free Software Foundation. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA #============================================================================ # Copyright (C) 2004, 2005 Mike Wray # Copyright (C) 2005 XenSource Ltd #============================================================================ from threading import Event from xen.xend import sxp from xen.xend.XendError import VmError from xen.xend.XendLogging import log from xen.xend.xenstore.xstransact import xstransact, complete from xen.xend.xenstore.xswatch import xswatch DEVICE_CREATE_TIMEOUT = 100 HOTPLUG_STATUS_NODE = "hotplug-status" HOTPLUG_ERROR_NODE = "hotplug-error" HOTPLUG_STATUS_ERROR = "error" HOTPLUG_STATUS_BUSY = "busy" Connected = 1 Error = 2 Missing = 3 Timeout = 4 Busy = 5 xenbusState = { 'Unknown' : 0, 'Initialising' : 1, 'InitWait' : 2, 'Initialised' : 3, 'Connected' : 4, 'Closing' : 5, 'Closed' : 6, } xenbusState.update(dict(zip(xenbusState.values(), xenbusState.keys()))) class DevController: """Abstract base class for a device controller. Device controllers create appropriate entries in the store to trigger the creation, reconfiguration, and destruction of devices in guest domains. Each subclass of DevController is responsible for a particular device-class, and understands the details of configuration specific to that device-class. DevController itself provides the functionality common to all device creation tasks, as well as providing an interface to XendDomainInfo for triggering those events themselves. """ # Set when registered. deviceClass = None ## public: def __init__(self, vm): self.vm = vm def createDevice(self, config): """Trigger the creation of a device with the given configuration. @return The ID for the newly created device. """ (devid, back, front) = self.getDeviceDetails(config) if devid is None: return 0 (backpath, frontpath) = self.addStoreEntries(config, devid, back, front) import xen.xend.XendDomain xd = xen.xend.XendDomain.instance() backdom_name = sxp.child_value(config, 'backend') if backdom_name is None: backdom = xen.xend.XendDomain.PRIV_DOMAIN else: bd = xd.domain_lookup_by_name_or_id_nr(backdom_name) backdom = bd.getDomid() count = 0 while True: t = xstransact() try: if devid in self.deviceIDs(t): if 'dev' in back: dev_str = '%s (%d, %s)' % (back['dev'], devid, self.deviceClass) else: dev_str = '%s (%s)' % (devid, self.deviceClass) raise VmError("Device %s is already connected." % dev_str) if count == 0: log.debug('DevController: writing %s to %s.', str(front), frontpath) log.debug('DevController: writing %s to %s.', str(back), backpath) elif count % 50 == 0: log.debug( 'DevController: still waiting to write device entries.') t.remove(frontpath) t.remove(backpath) t.mkdir(backpath) t.set_permissions(backpath, {'dom': backdom }, {'dom' : self.vm.getDomid(), 'read' : True }) t.mkdir(frontpath) t.set_permissions(frontpath, {'dom': self.vm.getDomid()}, {'dom': backdom, 'read': True}) t.write2(frontpath, front) t.write2(backpath, back) if t.commit(): return devid count += 1 except: t.abort() raise def waitForDevices(self): log.debug("Waiting for devices %s.", self.deviceClass) return map(self.waitForDevice, self.deviceIDs()) def waitForDevice(self, devid): log.debug("Waiting for %s.", devid) status = self.waitForBackend(devid) if status == Timeout: self.destroyDevice(devid) raise VmError("Device %s (%s) could not be connected. " "Hotplug scripts not working." % (devid, self.deviceClass)) elif status == Error: self.destroyDevice(devid) raise VmError("Device %s (%s) could not be connected. " "Backend device not found." % (devid, self.deviceClass)) elif status == Missing: # Don't try to destroy the device; it's already gone away. raise VmError("Device %s (%s) could not be connected. " "Device not found." % (devid, self.deviceClass)) elif status == Busy: err = None frontpath = self.frontendPath(devid) backpath = xstransact.Read(frontpath, "backend") if backpath: err = xstransact.Read(backpath, HOTPLUG_ERROR_NODE) if not err: err = "Busy." self.destroyDevice(devid) raise VmError("Device %s (%s) could not be connected.\n%s" % (devid, self.deviceClass, err)) def reconfigureDevice(self, devid, config): """Reconfigure the specified device. The implementation here just raises VmError. This may be overridden by those subclasses that can reconfigure their devices. """ raise VmError('%s devices may not be reconfigured' % self.deviceClass) def destroyDevice(self, devid): """Destroy the specified device. @param devid The device ID, or something device-specific from which the device ID can be determined (such as a guest-side device name). The implementation here simply deletes the appropriate paths from the store. This may be overridden by subclasses who need to perform other tasks on destruction. Further, the implementation here can only accept integer device IDs, or values that can be converted to integers. Subclasses may accept other values and convert them to integers before passing them here. """ devid = int(devid) # Modify online status /before/ updating state (latter is watched by # drivers, so this ordering avoids a race). self.writeBackend(devid, 'online', "0") self.writeBackend(devid, 'state', str(xenbusState['Closing'])) def configurations(self): return map(self.configuration, self.deviceIDs()) def configuration(self, devid): """@return an s-expression giving the current configuration of the specified device. This would be suitable for giving to {@link #createDevice} in order to recreate that device.""" backdomid = xstransact.Read(self.frontendPath(devid), "backend-id") if backdomid is None: raise VmError("Device %s not connected" % devid) return [self.deviceClass, ['backend', int(backdomid)]] def sxprs(self): """@return an s-expression describing all the devices of this controller's device-class. """ return xstransact.ListRecursive(self.frontendRoot()) def sxpr(self, devid): """@return an s-expression describing the specified device. """ return [self.deviceClass, ['dom', self.vm.getDomid(), 'id', devid]] ## protected: def getDeviceDetails(self, config): """Compute the details for creation of a device corresponding to the given configuration. These details consist of a tuple of (devID, backDetails, frontDetails), where devID is the ID for the new device, and backDetails and frontDetails are the device configuration specifics for the backend and frontend respectively. backDetails and frontDetails should be dictionaries, the keys and values of which will be used as paths in the store. There is no need for these dictionaries to include the references from frontend to backend, nor vice versa, as these will be handled by DevController. Abstract; must be implemented by every subclass. @return (devID, backDetails, frontDetails), as specified above. """ raise NotImplementedError() def migrate(self, deviceConfig, network, dst, step, domName): """ Migration of a device. The 'network' parameter indicates whether the device is network-migrated (True). 'dst' then gives the hostname of the machine to migrate to. This function is called for 4 steps: If step == 0: Check whether the device is ready to be migrated or can at all be migrated; return a '-1' if the device is NOT ready, a '0' otherwise. If it is not ready ( = not possible to migrate this device), migration will not take place. step == 1: Called immediately after step 0; migration of the kernel has started; step == 2: Called after the suspend has been issued to the domain and the domain is not scheduled anymore. Synchronize with what was started in step 1, if necessary. Now the device should initiate its transfer to the given target. Since there might be more than just one device initiating a migration, this step should put the process performing the transfer into the background and return immediately to achieve as much concurrency as possible. step == 3: Synchronize with the migration of the device that was initiated in step 2. Make sure that the migration has finished and only then return from the call. """ return 0 def recover_migrate(self, deviceConfig, network, dst, step, domName): """ Recover from device migration. The given step was the last one that was successfully executed. """ return 0 def getDomid(self): """Stub to {@link XendDomainInfo.getDomid}, for use by our subclasses. """ return self.vm.getDomid() def allocateDeviceID(self): """Allocate a device ID, allocating them consecutively on a per-domain, per-device-class basis, and using the store to record the next available ID. This method is available to our subclasses, though it is not compulsory to use it; subclasses may prefer to allocate IDs based upon the device configuration instead. """ path = self.frontendMiscPath() return complete(path, self._allocateDeviceID) def _allocateDeviceID(self, t): result = t.read("nextDeviceID") if result: result = int(result) else: result = 0 t.write("nextDeviceID", str(result + 1)) return result def readBackend(self, devid, *args): frontpath = self.frontendPath(devid) backpath = xstransact.Read(frontpath, "backend") if backpath: return xstransact.Read(backpath, *args) else: raise VmError("Device %s not connected" % devid) def readFrontend(self, devid, *args): return xstransact.Read(self.frontendPath(devid), *args) def deviceIDs(self, transaction = None): """@return The IDs of each of the devices currently configured for this instance's deviceClass. """ fe = self.backendRoot() if transaction: return map(lambda x: int(x.split('/')[-1]), transaction.list(fe)) else: return map(int, xstransact.List(fe)) def writeBackend(self, devid, *args): frontpath = self.frontendPath(devid) backpath = xstransact.Read(frontpath, "backend") if backpath: xstransact.Write(backpath, *args) else: raise VmError("Device %s not connected" % devid) ## private: def addStoreEntries(self, config, devid, backDetails, frontDetails): """Add to backDetails and frontDetails the entries to be written in the store to trigger creation of a device. The backend domain ID is taken from the given config, paths for frontend and backend are computed, and these are added to the backDetails and frontDetails dictionaries for writing to the store, including references from frontend to backend and vice versa. @return A pair of (backpath, frontpath). backDetails and frontDetails will have been updated appropriately, also. @param config The configuration of the device, as given to {@link #createDevice}. @param devid As returned by {@link #getDeviceDetails}. @param backDetails As returned by {@link #getDeviceDetails}. @param frontDetails As returned by {@link #getDeviceDetails}. """ import xen.xend.XendDomain xd = xen.xend.XendDomain.instance() backdom_name = sxp.child_value(config, 'backend') if backdom_name: backdom = xd.domain_lookup_by_name_or_id_nr(backdom_name) else: backdom = xd.privilegedDomain() if not backdom: raise VmError("Cannot configure device for unknown backend %s" % backdom_name) frontpath = self.frontendPath(devid) backpath = self.backendPath(backdom, devid) frontDetails.update({ 'backend' : backpath, 'backend-id' : "%i" % backdom.getDomid(), 'state' : str(xenbusState['Initialising']) }) backDetails.update({ 'domain' : self.vm.getName(), 'frontend' : frontpath, 'frontend-id' : "%i" % self.vm.getDomid(), 'state' : str(xenbusState['Initialising']), 'online' : "1" }) return (backpath, frontpath) def waitForBackend(self, devid): frontpath = self.frontendPath(devid) backpath = xstransact.Read(frontpath, "backend") if backpath: statusPath = backpath + '/' + HOTPLUG_STATUS_NODE ev = Event() result = { 'status': Timeout } xswatch(statusPath, hotplugStatusCallback, ev, result) ev.wait(DEVICE_CREATE_TIMEOUT) return result['status'] else: return Missing def backendPath(self, backdom, devid): """@param backdom [XendDomainInfo] The backend domain info.""" return "%s/backend/%s/%s/%d" % (backdom.getDomainPath(), self.deviceClass, self.vm.getDomid(), devid) def frontendPath(self, devid): return "%s/%d" % (self.frontendRoot(), devid) def frontendRoot(self): return "%s/device/%s" % (self.vm.getDomainPath(), self.deviceClass) def backendRoot(self): import xen.xend.XendDomain from xen.xend.xenstore.xsutil import GetDomainPath backdom = xen.xend.XendDomain.PRIV_DOMAIN return "%s/backend/%s/%s" % (GetDomainPath(backdom), self.deviceClass, self.vm.getDomid()) def frontendMiscPath(self): return "%s/device-misc/%s" % (self.vm.getDomainPath(), self.deviceClass) def hotplugStatusCallback(statusPath, ev, result): log.debug("hotplugStatusCallback %s.", statusPath) status = xstransact.Read(statusPath) if status is not None: if status == HOTPLUG_STATUS_ERROR: result['status'] = Error elif status == HOTPLUG_STATUS_BUSY: result['status'] = Busy else: result['status'] = Connected else: return 1 log.debug("hotplugStatusCallback %d.", result['status']) ev.set() return 0