Preload disposables

For: QubesOS/qubes-issues#1512

Author: ben-grande

qubes/api/internal.py

@@ -361,3 +361,65 @@ async def suspend_post(self):
                         qubes.config.suspend_timeout,
                         "qubes.SuspendPostAll",
                     )
+
+    @qubes.api.method(
+        "internal.dispvm.preload.Create", scope="local", write=True
+    )
+    async def dispvm_preload_create(self):
+        """
+        Method called to create a preloaded DispVM.
+
+        :return:
+        """
+        dispvm_template = self.arg
+        preload_dispvm = dispvm_template.features.get("preload-dispvm", None)
+        ## TODO: should this function receive disposable name as argument
+        ##       or call admin.vm.CreateDisposable?
+        dispvm = TODO
+        if preload_dispvm:
+            preload_dispvm += " " + dispvm
+        else:
+            preload_dispvm = dispvm
+        dispvm_template.features["preload-dispvm"] = preload_dispvm
+        dispvm.features["internal"] = True
+
+    @qubes.api.method(
+        "internal.dispvm.preload.Use", scope="local", write=True
+    )
+    async def dispvm_preload_use(self):
+        """
+        Method called when usage of preloaded DispVM is requested.
+
+        To use the first preloaded disposable, provide as argument the
+        disposable template, else, provide as argument the disposable name.
+
+        :return:
+        """
+        used_dispvm = self.arg
+        if used_dispvm.klass == "DispVM":
+            dispvm_template = getattr(used_dispvm, "template")
+            use_first = False
+        elif (
+            used_dispvm.klass == "AppVM"
+            and getattr(used_dispvm, "template_for_dispvms", False)
+        ):
+            dispvm_template = used_dispvm
+            use_first = True
+        else:
+            raise qubes.exc.QubesException("Invalid argument provided")
+        preload_dispvm = dispvm_template.features.get("preload-dispvm", None)
+        if not preload_dispvm:
+            return
+
+        preload_dispvm = preload_dispvm.split(" ")
+        if use_first:
+            used_dispvm_name = preload_dispvm[1:]
+        else:
+            used_dispvm_name = used_dispvm.name
+
+        unused_dispvm = preload_dispvm.remove(used_dispvm_name)
+        dispvm_template.features["preload-dispvm"] = unused_dispvm
+        used_dispvm.features["internal"] = False
+        ## TODO: preload next disposable with delay. Should this function
+        ##       emit an event to handle the delay and creation of the next
+        ##        preloaded disposable?

qubes/vm/dispvm.py

@@ -187,11 +187,37 @@ def __init__(self, app, xml, *args, **kwargs):
             self.features.update(template.features)
             self.tags.update(template.tags)
 
+    def is_domain_preloaded(self):
+        preload_dispvm = (
+            self.features.check_with_template("preload-dispvm", None)
+        )
+        if not preload_dispvm:
+            return False
+        preload_dispvm = preload_dispvm.split(" ")
+        if self.name not in preload_dispvm:
+            return False
+        return True
+
+
     @qubes.events.handler("domain-load")
     def on_domain_loaded(self, event):
         """When domain is loaded assert that this vm has a template."""  # pylint: disable=unused-argument
         assert self.template
 
+    @qubes.events.handler("domain-started")
+    def on_domain_started(self, event, **kwargs):
+        """Pause preloaded domains as soon as they start."""
+        if self.is_domain_preloaded():
+            self.pause()
+
+    @qubes.events.handler("domain-unpaused")
+    def on_domain_unpaused(self):
+        """Mark unpaused preloaded domains as used."""
+        if self.is_domain_preloaded():
+            self.app.qubesd_call(
+                "dom0", "internal.dispvm.preload.Use", self.name
+            )
+
     @qubes.events.handler("property-pre-reset:template")
     def on_property_pre_reset_template(self, event, name, oldvalue=None):
         """Forbid deleting template of VM"""  # pylint: disable=unused-argument
@@ -251,6 +277,15 @@ async def from_appvm(cls, appvm, **kwargs):
                 "template_for_dispvms=False"
             )
         app = appvm.app
+
+        preload_dispvm = appvm.features.get("preload-dispvm", None)
+        if preload_dispvm:
+            dispvm = preload_dispvm.split(" ")[0]
+            app.qubesd_call(
+                "dom0", "internal.dispvm.preload.Use", dispvm
+            )
+            return dispvm
+
         dispvm = app.add_new_vm(
             cls, template=appvm, auto_cleanup=True, **kwargs
         )