087a02c7f4
Migrate meminfo-writer=False service setting to maxmem=0 as a method to disable dynamic memory management. Remove the service from vm.features dict in the process. Additionally, translate any attempt to set the service.meminfo-writer feature to either setting maxmem=0 or resetting it to the default (which is memory balancing enabled if supported by given domain). This is to at least partially not break existing tools using service.meminfo-writer as a way to control dynamic memory management. This code does _not_ support reading service.meminfo-writer feature state to get the current state of dynamic memory management, as it would require synchronizing with all the factors affecting its value. One of main reasons for migrating to maxmem=0 approach is to avoid the need of such synchronization. QubesOS/qubes-issues#4480
134 lines
5.3 KiB
Python
134 lines
5.3 KiB
Python
# -*- encoding: utf-8 -*-
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#
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# The Qubes OS Project, http://www.qubes-os.org
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#
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# Copyright (C) 2017 Marek Marczykowski-Górecki
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# <marmarek@invisiblethingslab.com>
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, see <https://www.gnu.org/licenses/>.
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'''Extension responsible for qvm-service framework'''
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import qubes.ext
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class ServicesExtension(qubes.ext.Extension):
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'''This extension export features with 'service.' prefix to QubesDB in
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/qubes-service/ tree.
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'''
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# pylint: disable=no-self-use
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@qubes.ext.handler('domain-qdb-create')
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def on_domain_qdb_create(self, vm, event):
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'''Actually export features'''
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# pylint: disable=unused-argument
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for feature, value in vm.features.items():
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if not feature.startswith('service.'):
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continue
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service = feature[len('service.'):]
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# forcefully convert to '0' or '1'
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vm.untrusted_qdb.write('/qubes-service/{}'.format(service),
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str(int(bool(value))))
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# always set meminfo-writer according to maxmem
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vm.untrusted_qdb.write('/qubes-service/meminfo-writer',
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'1' if vm.maxmem > 0 else '0')
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@qubes.ext.handler('domain-feature-set:*')
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def on_domain_feature_set(self, vm, event, feature, value, oldvalue=None):
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'''Update /qubes-service/ QubesDB tree in runtime'''
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# pylint: disable=unused-argument
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# TODO: remove this compatibility hack in Qubes 4.1
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if feature == 'service.meminfo-writer':
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# if someone try to enable meminfo-writer ...
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if value:
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# ... reset maxmem to default
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vm.maxmem = qubes.property.DEFAULT
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else:
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# otherwise, set to 0
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vm.maxmem = 0
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# in any case, remove the entry, as it does not indicate memory
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# balancing state anymore
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del vm.features['service.meminfo-writer']
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if not vm.is_running():
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return
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if not feature.startswith('service.'):
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return
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service = feature[len('service.'):]
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# forcefully convert to '0' or '1'
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vm.untrusted_qdb.write('/qubes-service/{}'.format(service),
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str(int(bool(value))))
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@qubes.ext.handler('domain-feature-delete:*')
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def on_domain_feature_delete(self, vm, event, feature):
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'''Update /qubes-service/ QubesDB tree in runtime'''
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# pylint: disable=unused-argument
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if not vm.is_running():
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return
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if not feature.startswith('service.'):
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return
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service = feature[len('service.'):]
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# this one is excluded from user control
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if service == 'meminfo-writer':
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return
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vm.untrusted_qdb.rm('/qubes-service/{}'.format(service))
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@qubes.ext.handler('domain-load')
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def on_domain_load(self, vm, event):
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'''Migrate meminfo-writer service into maxmem'''
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# pylint: disable=no-self-use,unused-argument
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if 'service.meminfo-writer' in vm.features:
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# if was set to false, force maxmem=0
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# otherwise, simply ignore as the default is fine
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if not vm.features['service.meminfo-writer']:
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vm.maxmem = 0
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del vm.features['service.meminfo-writer']
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@qubes.ext.handler('features-request')
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def supported_services(self, vm, event, untrusted_features):
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'''Handle advertisement of supported services'''
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# pylint: disable=no-self-use,unused-argument
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if getattr(vm, 'template', None):
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vm.log.warning(
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'Ignoring qubes.FeaturesRequest from template-based VM')
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return
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new_supported_services = set()
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for requested_service in untrusted_features:
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if not requested_service.startswith('supported-service.'):
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continue
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if untrusted_features[requested_service] == '1':
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# only allow to advertise service as supported, lack of entry
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# means service is not supported
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new_supported_services.add(requested_service)
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del untrusted_features
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# if no service is supported, ignore the whole thing - do not clear
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# all services in case of empty request (manual or such)
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if not new_supported_services:
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return
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old_supported_services = set(
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feat for feat in vm.features
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if feat.startswith('supported-service.') and vm.features[feat])
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for feature in new_supported_services.difference(
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old_supported_services):
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vm.features[feature] = True
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for feature in old_supported_services.difference(
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new_supported_services):
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del vm.features[feature]
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