1 /*
2  * Copyright (C) 2021 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.system.virtualmachine;
18 
19 import android.annotation.NonNull;
20 import android.os.IBinder;
21 import android.os.ParcelFileDescriptor;
22 import android.system.virtualizationservice.IVirtualizationService;
23 
24 import com.android.internal.annotations.GuardedBy;
25 
26 import java.lang.ref.WeakReference;
27 
28 /** A running instance of virtmgr that is hosting a VirtualizationService AIDL service. */
29 class VirtualizationService {
30     static {
31         System.loadLibrary("virtualizationservice_jni");
32     }
33 
34     /* Soft reference caching the last created instance of this class. */
35     @GuardedBy("VirtualMachineManager.sCreateLock")
36     private static WeakReference<VirtualizationService> sInstance;
37 
38     /*
39      * Client FD for UDS connection to virtmgr's RpcBinder server. Closing it
40      * will make virtmgr shut down.
41      */
42     private final ParcelFileDescriptor mClientFd;
43 
44     /* Persistent connection to IVirtualizationService. */
45     private final IVirtualizationService mBinder;
46 
nativeSpawn()47     private static native int nativeSpawn();
48 
nativeConnect(int clientFd)49     private native IBinder nativeConnect(int clientFd);
50 
nativeIsOk(int clientFd)51     private native boolean nativeIsOk(int clientFd);
52 
53     /*
54      * Retrieve boolean value whether RELEASE_AVF_ENABLE_VENDOR_MODULES build flag is enabled or
55      * not.
56      */
nativeIsVendorModulesFlagEnabled()57     static native boolean nativeIsVendorModulesFlagEnabled();
58 
59     /*
60      * Spawns a new virtmgr subprocess that will host a VirtualizationService
61      * AIDL service.
62      */
VirtualizationService()63     private VirtualizationService() throws VirtualMachineException {
64         int clientFd = nativeSpawn();
65         if (clientFd < 0) {
66             throw new VirtualMachineException("Could not spawn Virtualization Manager");
67         }
68         mClientFd = ParcelFileDescriptor.adoptFd(clientFd);
69 
70         IBinder binder = nativeConnect(mClientFd.getFd());
71         if (binder == null) {
72             throw new VirtualMachineException("Could not connect to Virtualization Manager");
73         }
74         mBinder = IVirtualizationService.Stub.asInterface(binder);
75     }
76 
77     /* Returns the IVirtualizationService binder. */
78     @NonNull
getBinder()79     IVirtualizationService getBinder() {
80         return mBinder;
81     }
82 
83     /*
84      * Checks the state of the client FD. Returns false if the FD is in erroneous state
85      * or if the other endpoint had closed its FD.
86      */
isOk()87     private boolean isOk() {
88         return nativeIsOk(mClientFd.getFd());
89     }
90 
91     /*
92      * Returns an instance of this class. Might spawn a new instance if one doesn't exist, or
93      * if the previous instance had crashed.
94      */
95     @GuardedBy("VirtualMachineManager.sCreateLock")
96     @NonNull
getInstance()97     static VirtualizationService getInstance() throws VirtualMachineException {
98         VirtualizationService service = (sInstance == null) ? null : sInstance.get();
99         if (service == null || !service.isOk()) {
100             service = new VirtualizationService();
101             sInstance = new WeakReference<>(service);
102         }
103         return service;
104     }
105 }
106