summaryrefslogtreecommitdiffstats
path: root/src/VBox/VMM/VMMR3/DBGF.cpp
blob: 1563ac0ca49623e0a4c0f3ea2c78acf8888f0be9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
/* $Id: DBGF.cpp $ */
/** @file
 * DBGF - Debugger Facility.
 */

/*
 * Copyright (C) 2006-2023 Oracle and/or its affiliates.
 *
 * This file is part of VirtualBox base platform packages, as
 * available from https://www.virtualbox.org.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation, in version 3 of the
 * License.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <https://www.gnu.org/licenses>.
 *
 * SPDX-License-Identifier: GPL-3.0-only
 */


/** @page   pg_dbgf     DBGF - The Debugger Facility
 *
 * The purpose of the DBGF is to provide an interface for debuggers to
 * manipulate the VMM without having to mess up the source code for each of
 * them. The DBGF is always built in and will always work when a debugger
 * attaches to the VM. The DBGF provides the basic debugger features, such as
 * halting execution, handling breakpoints, single step execution, instruction
 * disassembly, info querying, OS specific diggers, symbol and module
 * management.
 *
 * The interface is working in a manner similar to the win32, linux and os2
 * debugger interfaces. The interface has an asynchronous nature. This comes
 * from the fact that the VMM and the Debugger are running in different threads.
 * They are referred to as the "emulation thread" and the "debugger thread", or
 * as the "ping thread" and the "pong thread, respectivly. (The last set of
 * names comes from the use of the Ping-Pong synchronization construct from the
 * RTSem API.)
 *
 * @see grp_dbgf
 *
 *
 * @section sec_dbgf_scenario   Usage Scenario
 *
 * The debugger starts by attaching to the VM. For practical reasons we limit the
 * number of concurrently attached debuggers to 1 per VM. The action of
 * attaching to the VM causes the VM to check and generate debug events.
 *
 * The debugger then will wait/poll for debug events and issue commands.
 *
 * The waiting and polling is done by the DBGFEventWait() function. It will wait
 * for the emulation thread to send a ping, thus indicating that there is an
 * event waiting to be processed.
 *
 * An event can be a response to a command issued previously, the hitting of a
 * breakpoint, or running into a bad/fatal VMM condition. The debugger now has
 * the ping and must respond to the event at hand - the VMM is waiting. This
 * usually means that the user of the debugger must do something, but it doesn't
 * have to. The debugger is free to call any DBGF function (nearly at least)
 * while processing the event.
 *
 * Typically the user will issue a request for the execution to be resumed, so
 * the debugger calls DBGFResume() and goes back to waiting/polling for events.
 *
 * When the user eventually terminates the debugging session or selects another
 * VM, the debugger detaches from the VM. This means that breakpoints are
 * disabled and that the emulation thread no longer polls for debugger commands.
 *
 */


/*********************************************************************************************************************************
*   Header Files                                                                                                                 *
*********************************************************************************************************************************/
#define LOG_GROUP LOG_GROUP_DBGF
#include <VBox/vmm/dbgf.h>
#include <VBox/vmm/selm.h>
#include <VBox/vmm/em.h>
#include <VBox/vmm/hm.h>
#include <VBox/vmm/mm.h>
#include <VBox/vmm/nem.h>
#include "DBGFInternal.h"
#include <VBox/vmm/vm.h>
#include <VBox/vmm/uvm.h>
#include <VBox/err.h>

#include <VBox/log.h>
#include <iprt/semaphore.h>
#include <iprt/thread.h>
#include <iprt/asm.h>
#include <iprt/time.h>
#include <iprt/assert.h>
#include <iprt/stream.h>
#include <iprt/env.h>


/*********************************************************************************************************************************
*   Structures and Typedefs                                                                                                      *
*********************************************************************************************************************************/
/**
 * Instruction type returned by dbgfStepGetCurInstrType.
 */
typedef enum DBGFSTEPINSTRTYPE
{
    DBGFSTEPINSTRTYPE_INVALID = 0,
    DBGFSTEPINSTRTYPE_OTHER,
    DBGFSTEPINSTRTYPE_RET,
    DBGFSTEPINSTRTYPE_CALL,
    DBGFSTEPINSTRTYPE_END,
    DBGFSTEPINSTRTYPE_32BIT_HACK = 0x7fffffff
} DBGFSTEPINSTRTYPE;


/*********************************************************************************************************************************
*   Internal Functions                                                                                                           *
*********************************************************************************************************************************/
DECLINLINE(int) dbgfR3SendEventWait(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmType, DBGFEVENTCTX enmCtx);
DECLINLINE(DBGFCMD) dbgfR3CpuGetCmd(PUVMCPU pUVCpu);
static int dbgfR3CpuWait(PVMCPU pVCpu);
static int dbgfR3CpuCmd(PVMCPU pVCpu, DBGFCMD enmCmd, PDBGFCMDDATA pCmdData, bool *pfResumeExecution);
static DBGFSTEPINSTRTYPE dbgfStepGetCurInstrType(PVM pVM, PVMCPU pVCpu);
static bool dbgfStepAreWeThereYet(PVM pVM, PVMCPU pVCpu);
static int dbgfR3EventHaltAllVCpus(PVM pVM, PVMCPU pVCpuExclude);



/**
 * Initializes the DBGF.
 *
 * @returns VBox status code.
 * @param   pVM     The cross context VM structure.
 */
VMMR3_INT_DECL(int) DBGFR3Init(PVM pVM)
{
    PUVM pUVM = pVM->pUVM;
    AssertCompile(sizeof(pUVM->dbgf.s)          <= sizeof(pUVM->dbgf.padding));
    AssertCompile(sizeof(pUVM->aCpus[0].dbgf.s) <= sizeof(pUVM->aCpus[0].dbgf.padding));

    pVM->dbgf.s.SteppingFilter.idCpu = NIL_VMCPUID;

    /*
     * The usual sideways mountain climbing style of init:
     */
    int rc = dbgfR3InfoInit(pUVM); /* (First, initalizes the shared critical section.) */
    if (RT_SUCCESS(rc))
    {
        rc = dbgfR3TraceInit(pVM);
        if (RT_SUCCESS(rc))
        {
            rc = dbgfR3RegInit(pUVM);
            if (RT_SUCCESS(rc))
            {
                rc = dbgfR3AsInit(pUVM);
                if (RT_SUCCESS(rc))
                {
                    rc = dbgfR3BpInit(pUVM);
                    if (RT_SUCCESS(rc))
                    {
                        rc = dbgfR3OSInit(pUVM);
                        if (RT_SUCCESS(rc))
                        {
                            rc = dbgfR3PlugInInit(pUVM);
                            if (RT_SUCCESS(rc))
                            {
                                rc = dbgfR3BugCheckInit(pVM);
                                if (RT_SUCCESS(rc))
                                {
#ifdef VBOX_WITH_DBGF_TRACING
                                    rc = dbgfR3TracerInit(pVM);
#endif
                                    if (RT_SUCCESS(rc))
                                    {
                                        return VINF_SUCCESS;
                                    }
                                }
                                dbgfR3PlugInTerm(pUVM);
                            }
                            dbgfR3OSTermPart1(pUVM);
                            dbgfR3OSTermPart2(pUVM);
                        }
                        dbgfR3BpTerm(pUVM);
                    }
                    dbgfR3AsTerm(pUVM);
                }
                dbgfR3RegTerm(pUVM);
            }
            dbgfR3TraceTerm(pVM);
        }
        dbgfR3InfoTerm(pUVM);
    }
    return rc;
}


/**
 * Terminates and cleans up resources allocated by the DBGF.
 *
 * @returns VBox status code.
 * @param   pVM     The cross context VM structure.
 */
VMMR3_INT_DECL(int) DBGFR3Term(PVM pVM)
{
    PUVM pUVM = pVM->pUVM;

#ifdef VBOX_WITH_DBGF_TRACING
    dbgfR3TracerTerm(pVM);
#endif
    dbgfR3OSTermPart1(pUVM);
    dbgfR3PlugInTerm(pUVM);
    dbgfR3OSTermPart2(pUVM);
    dbgfR3BpTerm(pUVM);
    dbgfR3AsTerm(pUVM);
    dbgfR3RegTerm(pUVM);
    dbgfR3TraceTerm(pVM);
    dbgfR3InfoTerm(pUVM);

    return VINF_SUCCESS;
}


/**
 * This is for tstCFGM and others to avoid trigger leak detection.
 *
 * @param   pUVM    The user mode VM structure.
 */
VMMR3DECL(void) DBGFR3TermUVM(PUVM pUVM)
{
    dbgfR3InfoTerm(pUVM);
}


/**
 * Called when the VM is powered off to detach debuggers.
 *
 * @param   pVM     The cross context VM structure.
 */
VMMR3_INT_DECL(void) DBGFR3PowerOff(PVM pVM)
{
    /*
     * Send a termination event to any attached debugger.
     */
    if (pVM->dbgf.s.fAttached)
    {
        PVMCPU pVCpu = VMMGetCpu(pVM);
        int rc = dbgfR3SendEventWait(pVM, pVCpu, DBGFEVENT_POWERING_OFF, DBGFEVENTCTX_OTHER);
        AssertLogRelRC(rc);

        /*
         * Clear the FF so we won't get confused later on.
         */
        VM_FF_CLEAR(pVM, VM_FF_DBGF);
    }
}


/**
 * Applies relocations to data and code managed by this
 * component. This function will be called at init and
 * whenever the VMM need to relocate it self inside the GC.
 *
 * @param   pVM         The cross context VM structure.
 * @param   offDelta    Relocation delta relative to old location.
 */
VMMR3_INT_DECL(void) DBGFR3Relocate(PVM pVM, RTGCINTPTR offDelta)
{
    dbgfR3TraceRelocate(pVM);
    dbgfR3AsRelocate(pVM->pUVM, offDelta);
}


/**
 * Waits a little while for a debuggger to attach.
 *
 * @returns True is a debugger have attached.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The cross context per CPU structure.
 * @param   enmEvent    Event.
 *
 * @thread  EMT(pVCpu)
 */
bool dbgfR3WaitForAttach(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmEvent)
{
    /*
     * First a message.
     */
#if !defined(DEBUG)
    int cWait = 10;
#else
    int cWait = RTEnvExist("VBOX_DBGF_NO_WAIT_FOR_ATTACH")
             || (   (   enmEvent == DBGFEVENT_ASSERTION_HYPER
                     || enmEvent == DBGFEVENT_FATAL_ERROR)
                 && !RTEnvExist("VBOX_DBGF_WAIT_FOR_ATTACH"))
              ? 10
              : 150;
#endif
    RTStrmPrintf(g_pStdErr,
                 "DBGF: No debugger attached, waiting %d second%s for one to attach (event=%d)\n"
#ifdef DEBUG
                 "      Set VBOX_DBGF_NO_WAIT_FOR_ATTACH=1 for short wait or VBOX_DBGF_WAIT_FOR_ATTACH=1 longer.\n"
#endif
                 ,
                 cWait / 10, cWait != 10 ? "s" : "", enmEvent);
    RTStrmFlush(g_pStdErr);
    while (cWait > 0)
    {
        RTThreadSleep(100);
        if (pVM->dbgf.s.fAttached)
        {
            RTStrmPrintf(g_pStdErr, "Attached!\n");
            RTStrmFlush(g_pStdErr);
            return true;
        }

        /* Process rendezvous (debugger attaching involves such). */
        if (VM_FF_IS_SET(pVM, VM_FF_EMT_RENDEZVOUS))
        {
            int rc = VMMR3EmtRendezvousFF(pVM, pVCpu); AssertRC(rc);
            if (rc != VINF_SUCCESS)
            {
                /** @todo Ignoring these could be bad. */
                RTStrmPrintf(g_pStdErr, "[rcRendezvous=%Rrc, ignored!]", rc);
                RTStrmFlush(g_pStdErr);
            }
        }

        /* Process priority stuff. */
        if (   VM_FF_IS_SET(pVM, VM_FF_REQUEST)
            || VMCPU_FF_IS_SET(pVCpu, VMCPU_FF_REQUEST))
        {
            int rc = VMR3ReqProcessU(pVM->pUVM, VMCPUID_ANY, true /*fPriorityOnly*/);
            if (rc == VINF_SUCCESS)
                rc = VMR3ReqProcessU(pVM->pUVM, pVCpu->idCpu, true /*fPriorityOnly*/);
            if (rc != VINF_SUCCESS)
            {
                /** @todo Ignoring these could be bad. */
                RTStrmPrintf(g_pStdErr, "[rcReq=%Rrc, ignored!]", rc);
                RTStrmFlush(g_pStdErr);
            }
        }

        /* next */
        if (!(cWait % 10))
        {
            RTStrmPrintf(g_pStdErr, "%d.", cWait / 10);
            RTStrmFlush(g_pStdErr);
        }
        cWait--;
    }

    RTStrmPrintf(g_pStdErr, "Stopping the VM!\n");
    RTStrmFlush(g_pStdErr);
    return false;
}


/**
 * Forced action callback.
 *
 * The VMM will call this from it's main loop when either VM_FF_DBGF or
 * VMCPU_FF_DBGF are set.
 *
 * The function checks for and executes pending commands from the debugger.
 * Then it checks for pending debug events and serves these.
 *
 * @returns VINF_SUCCESS normally.
 * @returns VERR_DBGF_RAISE_FATAL_ERROR to pretend a fatal error happened.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The cross context per CPU structure.
 */
VMMR3_INT_DECL(int) DBGFR3VMMForcedAction(PVM pVM, PVMCPU pVCpu)
{
    VBOXSTRICTRC rcStrict = VINF_SUCCESS;

    /*
     * Dispatch pending events.
     */
    if (VMCPU_FF_TEST_AND_CLEAR(pVCpu, VMCPU_FF_DBGF))
    {
        if (   pVCpu->dbgf.s.cEvents > 0
            && pVCpu->dbgf.s.aEvents[pVCpu->dbgf.s.cEvents - 1].enmState == DBGFEVENTSTATE_CURRENT)
        {
            rcStrict = DBGFR3EventHandlePending(pVM, pVCpu);
            /** @todo may end up with VERR_DBGF_NOT_ATTACHED here, which will prove fatal... */
        }

        /*
         * Command pending? Process it.
         */
        PUVMCPU pUVCpu = pVCpu->pUVCpu;
        if (pUVCpu->dbgf.s.enmDbgfCmd != DBGFCMD_NO_COMMAND)
        {
            bool            fResumeExecution;
            DBGFCMDDATA     CmdData = pUVCpu->dbgf.s.DbgfCmdData;
            DBGFCMD         enmCmd = dbgfR3CpuGetCmd(pUVCpu);
            VBOXSTRICTRC rcStrict2 = dbgfR3CpuCmd(pVCpu, enmCmd, &CmdData, &fResumeExecution);
            if (!fResumeExecution)
                rcStrict2 = dbgfR3CpuWait(pVCpu);
            if (   rcStrict2 != VINF_SUCCESS
                && (   rcStrict == VINF_SUCCESS
                    || RT_FAILURE(rcStrict2)
                    || rcStrict2 < rcStrict) ) /** @todo oversimplified? */
                rcStrict = rcStrict2;
        }
    }

    return VBOXSTRICTRC_TODO(rcStrict);
}


/**
 * Try to determine the event context.
 *
 * @returns debug event context.
 * @param   pVCpu       The cross context vCPU structure.
 */
static DBGFEVENTCTX dbgfR3FigureEventCtx(PVMCPU pVCpu)
{
    switch (EMGetState(pVCpu))
    {
        case EMSTATE_HM:
        case EMSTATE_NEM:
        case EMSTATE_DEBUG_GUEST_HM:
        case EMSTATE_DEBUG_GUEST_NEM:
            return DBGFEVENTCTX_HM;

        case EMSTATE_IEM:
        case EMSTATE_RAW:
        case EMSTATE_IEM_THEN_REM:
        case EMSTATE_DEBUG_GUEST_IEM:
        case EMSTATE_DEBUG_GUEST_RAW:
            return DBGFEVENTCTX_RAW;


        case EMSTATE_REM:
        case EMSTATE_DEBUG_GUEST_REM:
            return DBGFEVENTCTX_REM;

        case EMSTATE_DEBUG_HYPER:
        case EMSTATE_GURU_MEDITATION:
            return DBGFEVENTCTX_HYPER;

        default:
            return DBGFEVENTCTX_OTHER;
    }
}


/**
 * Sends the event to the debugger (i.e. adds it to the event ring buffer).
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The CPU sending the event.
 * @param   enmType     The event type to send.
 * @param   enmCtx      The event context, DBGFEVENTCTX_INVALID will be resolved.
 * @param   pvPayload   Event payload (DBGFEVENT::u data), optional.
 * @param   cbPayload   The size of the event payload, optional.
 */
static int dbgfR3SendEventWorker(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmType, DBGFEVENTCTX enmCtx,
                                 void const *pvPayload, size_t cbPayload)
{
    PUVM pUVM = pVM->pUVM;
    pVM->dbgf.s.SteppingFilter.idCpu = NIL_VMCPUID; /** @todo per vCPU stepping filter. */

    /*
     * Massage the input a little.
     */
    AssertStmt(cbPayload <= RT_SIZEOFMEMB(DBGFEVENT, u), cbPayload = RT_SIZEOFMEMB(DBGFEVENT, u));
    if (enmCtx == DBGFEVENTCTX_INVALID)
        enmCtx = dbgfR3FigureEventCtx(pVCpu);

    /*
     * Put the event into the ring buffer.
     */
    RTSemFastMutexRequest(pUVM->dbgf.s.hMtxDbgEvtWr);

    uint32_t const cDbgEvtMax     = RT_MAX(1, pUVM->dbgf.s.cDbgEvtMax);
    uint32_t const idxDbgEvtWrite = ASMAtomicReadU32(&pUVM->dbgf.s.idxDbgEvtWrite);
    uint32_t const idxDbgEvtRead  = ASMAtomicReadU32(&pUVM->dbgf.s.idxDbgEvtRead);
    /** @todo Handle full buffer. */ RT_NOREF(idxDbgEvtRead);

    PDBGFEVENT pEvent = &pUVM->dbgf.s.paDbgEvts[idxDbgEvtWrite % cDbgEvtMax];

#ifdef DEBUG
    ASMMemFill32(pEvent, sizeof(*pEvent), UINT32_C(0xdeadbeef));
#endif
    pEvent->enmType   = enmType;
    pEvent->enmCtx    = enmCtx;
    pEvent->idCpu     = pVCpu->idCpu;
    pEvent->uReserved = 0;
    if (cbPayload)
        memcpy(&pEvent->u, pvPayload, cbPayload);

    ASMAtomicWriteU32(&pUVM->dbgf.s.idxDbgEvtWrite, (idxDbgEvtWrite + 1) % cDbgEvtMax);

    RTSemFastMutexRelease(pUVM->dbgf.s.hMtxDbgEvtWr);

    /*
     * Signal the debugger.
     */
    return RTSemEventSignal(pUVM->dbgf.s.hEvtWait);
}


/**
 * Send event and wait for the debugger to respond.
 *
 * @returns Strict VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The CPU sending the event.
 * @param   enmType     The event type to send.
 * @param   enmCtx      The event context, DBGFEVENTCTX_INVALID will be resolved.
 */
DECLINLINE(int) dbgfR3SendEventWait(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmType, DBGFEVENTCTX enmCtx)
{
    int rc = dbgfR3SendEventWorker(pVM, pVCpu, enmType, enmCtx, NULL, 0);
    if (RT_SUCCESS(rc))
        rc = dbgfR3CpuWait(pVCpu);
    return rc;
}


/**
 * Send event and wait for the debugger to respond, extended version.
 *
 * @returns Strict VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The CPU sending the event.
 * @param   enmType     The event type to send.
 * @param   enmCtx      The event context, DBGFEVENTCTX_INVALID will be resolved.
 * @param   pvPayload   Event payload (DBGFEVENT::u data), optional.
 * @param   cbPayload   The size of the event payload, optional.
 */
DECLINLINE(int) dbgfR3SendEventWaitEx(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmType, DBGFEVENTCTX enmCtx,
                                      void const *pvPayload, size_t cbPayload)
{
    int rc = dbgfR3SendEventWorker(pVM, pVCpu, enmType, enmCtx, pvPayload, cbPayload);
    if (RT_SUCCESS(rc))
        rc = dbgfR3CpuWait(pVCpu);
    return rc;
}


/**
 * Send event but do NOT wait for the debugger.
 *
 * Currently only used by dbgfR3CpuCmd().
 *
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The CPU sending the event.
 * @param   enmType     The event type to send.
 * @param   enmCtx      The event context, DBGFEVENTCTX_INVALID will be resolved.
 */
DECLINLINE(int) dbgfR3SendEventNoWait(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmType, DBGFEVENTCTX enmCtx)
{
    return dbgfR3SendEventWorker(pVM, pVCpu, enmType, enmCtx, NULL, 0);
}


/**
 * The common event prologue code.
 *
 * It will make sure someone is attached, and perhaps process any high priority
 * pending actions (none yet).
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The vCPU cross context structure.
 * @param   enmEvent    The event to be sent.
 */
static int dbgfR3EventPrologue(PVM pVM, PVMCPU pVCpu, DBGFEVENTTYPE enmEvent)
{
    /*
     * Check if a debugger is attached.
     */
    if (    !pVM->dbgf.s.fAttached
        &&  !dbgfR3WaitForAttach(pVM, pVCpu, enmEvent))
    {
        Log(("dbgfR3EventPrologue: enmEvent=%d - debugger not attached\n", enmEvent));
        return VERR_DBGF_NOT_ATTACHED;
    }

    /*
     * Look thru pending commands and finish those which make sense now.
     */
    /** @todo Process/purge pending commands. */
    //int rc = DBGFR3VMMForcedAction(pVM);
    return VINF_SUCCESS;
}


/**
 * Processes a pending event on the current CPU.
 *
 * This is called by EM in response to VINF_EM_DBG_EVENT.
 *
 * @returns Strict VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The cross context per CPU structure.
 *
 * @thread  EMT(pVCpu)
 */
VMMR3_INT_DECL(VBOXSTRICTRC) DBGFR3EventHandlePending(PVM pVM, PVMCPU pVCpu)
{
    VMCPU_ASSERT_EMT(pVCpu);
    VMCPU_FF_CLEAR(pVCpu, VMCPU_FF_DBGF);

    /*
     * Check that we've got an event first.
     */
    AssertReturn(pVCpu->dbgf.s.cEvents > 0, VINF_SUCCESS);
    AssertReturn(pVCpu->dbgf.s.aEvents[pVCpu->dbgf.s.cEvents - 1].enmState == DBGFEVENTSTATE_CURRENT, VINF_SUCCESS);
    PDBGFEVENT pEvent = &pVCpu->dbgf.s.aEvents[pVCpu->dbgf.s.cEvents - 1].Event;

    /*
     * Make sure we've got a debugger and is allowed to speak to it.
     */
    int rc = dbgfR3EventPrologue(pVM, pVCpu, pEvent->enmType);
    if (RT_FAILURE(rc))
    {
        /** @todo drop them events?   */
        return rc; /** @todo this will cause trouble if we're here via an FF! */
    }

    /*
     * Send the event and mark it as ignore.
     * ASSUMES no new events get generate while dbgfR3CpuWait is executing!
     */
    VBOXSTRICTRC rcStrict = dbgfR3SendEventWaitEx(pVM, pVCpu, pEvent->enmType, pEvent->enmCtx, &pEvent->u, sizeof(pEvent->u));
    pVCpu->dbgf.s.aEvents[pVCpu->dbgf.s.cEvents - 1].enmState = DBGFEVENTSTATE_IGNORE;
    return rcStrict;
}


/**
 * Send a generic debugger event which takes no data.
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   enmEvent    The event to send.
 * @internal
 */
VMMR3DECL(int) DBGFR3Event(PVM pVM, DBGFEVENTTYPE enmEvent)
{
    PVMCPU pVCpu = VMMGetCpu(pVM);
    AssertReturn(pVCpu, VERR_VM_THREAD_NOT_EMT);

    /*
     * Do stepping filtering.
     */
    /** @todo Would be better if we did some of this inside the execution
     *        engines. */
    if (   enmEvent == DBGFEVENT_STEPPED
        || enmEvent == DBGFEVENT_STEPPED_HYPER)
    {
        if (!dbgfStepAreWeThereYet(pVM, pVCpu))
            return VINF_EM_DBG_STEP;
    }

    int rc = dbgfR3EventPrologue(pVM, pVCpu, enmEvent);
    if (RT_FAILURE(rc))
        return rc;

    /*
     * Send the event and process the reply communication.
     */
    return dbgfR3SendEventWait(pVM, pVCpu, enmEvent, DBGFEVENTCTX_INVALID);
}


/**
 * Send a debugger event which takes the full source file location.
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   enmEvent    The event to send.
 * @param   pszFile     Source file.
 * @param   uLine       Line number in source file.
 * @param   pszFunction Function name.
 * @param   pszFormat   Message which accompanies the event.
 * @param   ...         Message arguments.
 * @internal
 */
VMMR3DECL(int) DBGFR3EventSrc(PVM pVM, DBGFEVENTTYPE enmEvent, const char *pszFile, unsigned uLine, const char *pszFunction, const char *pszFormat, ...)
{
    va_list args;
    va_start(args, pszFormat);
    int rc = DBGFR3EventSrcV(pVM, enmEvent, pszFile, uLine, pszFunction, pszFormat, args);
    va_end(args);
    return rc;
}


/**
 * Send a debugger event which takes the full source file location.
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   enmEvent    The event to send.
 * @param   pszFile     Source file.
 * @param   uLine       Line number in source file.
 * @param   pszFunction Function name.
 * @param   pszFormat   Message which accompanies the event.
 * @param   args        Message arguments.
 * @internal
 */
VMMR3DECL(int) DBGFR3EventSrcV(PVM pVM, DBGFEVENTTYPE enmEvent, const char *pszFile, unsigned uLine, const char *pszFunction, const char *pszFormat, va_list args)
{
    PVMCPU pVCpu = VMMGetCpu(pVM);
    AssertReturn(pVCpu, VERR_VM_THREAD_NOT_EMT);

    int rc = dbgfR3EventPrologue(pVM, pVCpu, enmEvent);
    if (RT_FAILURE(rc))
        return rc;

    /*
     * Format the message.
     */
    char   *pszMessage = NULL;
    char    szMessage[8192];
    if (pszFormat && *pszFormat)
    {
        pszMessage = &szMessage[0];
        RTStrPrintfV(szMessage, sizeof(szMessage), pszFormat, args);
    }

    /*
     * Send the event and process the reply communication.
     */
    DBGFEVENT DbgEvent;  /** @todo split up DBGFEVENT so we can skip the dead wait on the stack? */
    DbgEvent.u.Src.pszFile      = pszFile;
    DbgEvent.u.Src.uLine        = uLine;
    DbgEvent.u.Src.pszFunction  = pszFunction;
    DbgEvent.u.Src.pszMessage   = pszMessage;
    return dbgfR3SendEventWaitEx(pVM, pVCpu, enmEvent, DBGFEVENTCTX_INVALID, &DbgEvent.u, sizeof(DbgEvent.u.Src));
}


/**
 * Send a debugger event which takes the two assertion messages.
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   enmEvent    The event to send.
 * @param   pszMsg1     First assertion message.
 * @param   pszMsg2     Second assertion message.
 */
VMMR3_INT_DECL(int) DBGFR3EventAssertion(PVM pVM, DBGFEVENTTYPE enmEvent, const char *pszMsg1, const char *pszMsg2)
{
    PVMCPU pVCpu = VMMGetCpu(pVM);
    AssertReturn(pVCpu, VERR_VM_THREAD_NOT_EMT);

    int rc = dbgfR3EventPrologue(pVM, pVCpu, enmEvent);
    if (RT_FAILURE(rc))
        return rc;

    /*
     * Send the event and process the reply communication.
     */
    DBGFEVENT DbgEvent;
    DbgEvent.u.Assert.pszMsg1 = pszMsg1;
    DbgEvent.u.Assert.pszMsg2 = pszMsg2;
    return dbgfR3SendEventWaitEx(pVM, pVCpu, enmEvent, DBGFEVENTCTX_INVALID, &DbgEvent.u, sizeof(DbgEvent.u.Assert));
}


/**
 * Breakpoint was hit somewhere.
 * Figure out which breakpoint it is and notify the debugger.
 *
 * @returns VBox status code.
 * @param   pVM         The cross context VM structure.
 * @param   enmEvent    DBGFEVENT_BREAKPOINT_HYPER or DBGFEVENT_BREAKPOINT.
 */
VMMR3_INT_DECL(int) DBGFR3EventBreakpoint(PVM pVM, DBGFEVENTTYPE enmEvent)
{
    PVMCPU pVCpu = VMMGetCpu(pVM);
    AssertReturn(pVCpu, VERR_VM_THREAD_NOT_EMT);

    int rc = dbgfR3EventPrologue(pVM, pVCpu, enmEvent);
    if (RT_FAILURE(rc))
        return rc;

    /*
     * Halt all other vCPUs as well to give the user the ability to inspect other
     * vCPU states as well.
     */
    rc = dbgfR3EventHaltAllVCpus(pVM, pVCpu);
    if (RT_FAILURE(rc))
        return rc;

    /*
     * Send the event and process the reply communication.
     */
    DBGFEVENT DbgEvent;
    DbgEvent.u.Bp.hBp = pVCpu->dbgf.s.hBpActive;
    pVCpu->dbgf.s.hBpActive = NIL_DBGFBP;
    if (DbgEvent.u.Bp.hBp != NIL_DBGFBP)
    {
        DbgEvent.enmCtx = DBGFEVENTCTX_RAW;
        return dbgfR3SendEventWaitEx(pVM, pVCpu, enmEvent, DBGFEVENTCTX_RAW, &DbgEvent.u, sizeof(DbgEvent.u.Bp));
    }

    return VERR_DBGF_IPE_1;
}


/**
 * Returns whether the given vCPU is waiting for the debugger.
 *
 * @returns Flags whether the vCPU is currently waiting for the debugger.
 * @param   pUVCpu              The user mode vCPU structure.
 */
DECLINLINE(bool) dbgfR3CpuIsHalted(PUVMCPU pUVCpu)
{
    return ASMAtomicReadBool(&pUVCpu->dbgf.s.fStopped);
}


/**
 * Checks whether the given vCPU is waiting in the debugger.
 *
 * @returns Flag whether the indicated vCPU is halted, when VMCPUID_ALL
 *          is given true is returned when at least one vCPU is halted.
 * @param   pUVM        The user mode VM structure.
 * @param   idCpu       The CPU ID to check, VMCPUID_ALL to check all vCPUs.
 */
DECLINLINE(bool) dbgfR3CpuAreAnyHaltedByCpuId(PUVM pUVM, VMCPUID idCpu)
{
    AssertReturn(idCpu < pUVM->cCpus || idCpu == VMCPUID_ALL, false);

    /* Check that either the given vCPU or all are actually halted. */
    if (idCpu != VMCPUID_ALL)
        return dbgfR3CpuIsHalted(&pUVM->aCpus[idCpu]);

    for (VMCPUID i = 0; i < pUVM->cCpus; i++)
        if (dbgfR3CpuIsHalted(&pUVM->aCpus[i]))
            return true;
    return false;
}


/**
 * Gets the pending debug command for this EMT/CPU, replacing it with
 * DBGFCMD_NO_COMMAND.
 *
 * @returns Pending command.
 * @param   pUVCpu          The user mode virtual CPU structure.
 * @thread  EMT(pUVCpu)
 */
DECLINLINE(DBGFCMD) dbgfR3CpuGetCmd(PUVMCPU pUVCpu)
{
    DBGFCMD enmCmd = (DBGFCMD)ASMAtomicXchgU32((uint32_t volatile *)(void *)&pUVCpu->dbgf.s.enmDbgfCmd, DBGFCMD_NO_COMMAND);
    Log2(("DBGF: Getting command: %d\n", enmCmd));
    return enmCmd;
}


/**
 * Send a debug command to a CPU, making sure to notify it.
 *
 * @returns VBox status code.
 * @param   pUVCpu      The user mode virtual CPU structure.
 * @param   enmCmd      The command to submit to the CPU.
 */
DECLINLINE(int) dbgfR3CpuSetCmdAndNotify(PUVMCPU pUVCpu, DBGFCMD enmCmd)
{
    Log2(("DBGF: Setting command to %d\n", enmCmd));
    Assert(enmCmd != DBGFCMD_NO_COMMAND);
    AssertMsg(pUVCpu->dbgf.s.enmDbgfCmd == DBGFCMD_NO_COMMAND, ("enmCmd=%d enmDbgfCmd=%d\n", enmCmd, pUVCpu->dbgf.s.enmDbgfCmd));

    ASMAtomicWriteU32((uint32_t volatile *)(void *)&pUVCpu->dbgf.s.enmDbgfCmd, enmCmd);
    VMCPU_FF_SET(pUVCpu->pVCpu, VMCPU_FF_DBGF);

    VMR3NotifyCpuFFU(pUVCpu, 0 /*fFlags*/);
    return VINF_SUCCESS;
}


/**
 * @callback_method_impl{FNVMMEMTRENDEZVOUS}
 */
static DECLCALLBACK(VBOXSTRICTRC) dbgfR3EventHaltEmtWorker(PVM pVM, PVMCPU pVCpu, void *pvUser)
{
    RT_NOREF(pvUser);

    VMCPU_ASSERT_EMT(pVCpu);
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);

    PUVMCPU pUVCpu = pVCpu->pUVCpu;
    if (   pVCpu != (PVMCPU)pvUser
        && !dbgfR3CpuIsHalted(pUVCpu))
        dbgfR3CpuSetCmdAndNotify(pUVCpu, DBGFCMD_HALT);

    return VINF_SUCCESS;
}


/**
 * Halts all vCPUs of the given VM except for the given one.
 *
 * @returns VBox status code.
 * @param   pVM             The cross context VM structure.
 * @param   pVCpuExclude    The vCPU cross context structure of the vCPU to exclude.
 */
static int dbgfR3EventHaltAllVCpus(PVM pVM, PVMCPU pVCpuExclude)
{
    return VMMR3EmtRendezvous(pVM, VMMEMTRENDEZVOUS_FLAGS_TYPE_ALL_AT_ONCE, dbgfR3EventHaltEmtWorker, pVCpuExclude);
}


/**
 * Waits for the debugger to respond.
 *
 * @returns VBox status code. (clearify)
 * @param   pVCpu               The cross context vCPU structure.
 */
static int dbgfR3CpuWait(PVMCPU pVCpu)
{
    PVM pVM = pVCpu->CTX_SUFF(pVM);
    PUVMCPU pUVCpu = pVCpu->pUVCpu;

    LogFlow(("dbgfR3CpuWait:\n"));
    int rcRet = VINF_SUCCESS;

    ASMAtomicWriteBool(&pUVCpu->dbgf.s.fStopped, true);

    /*
     * Waits for the debugger to reply (i.e. issue an command).
     */
    for (;;)
    {
        /*
         * Wait.
         */
        for (;;)
        {
            /*
             * Process forced flags before we go sleep.
             */
            if (   VMCPU_FF_IS_ANY_SET(pVCpu, VMCPU_FF_DBGF | VMCPU_FF_REQUEST)
                || VM_FF_IS_ANY_SET(pVM, VM_FF_EMT_RENDEZVOUS | VMCPU_FF_REQUEST | VM_FF_CHECK_VM_STATE))
            {
                if (VMCPU_FF_IS_SET(pVCpu, VMCPU_FF_DBGF))
                    break;

                int rc;
                if (VM_FF_IS_SET(pVM, VM_FF_EMT_RENDEZVOUS))
                    rc = VMMR3EmtRendezvousFF(pVM, pVCpu);
                else if (   VM_FF_IS_SET(pVM, VM_FF_REQUEST)
                         || VMCPU_FF_IS_SET(pVCpu, VMCPU_FF_REQUEST))
                {
                    LogFlow(("dbgfR3CpuWait: Processes requests...\n"));
                    rc = VMR3ReqProcessU(pVM->pUVM, VMCPUID_ANY, false /*fPriorityOnly*/);
                    if (rc == VINF_SUCCESS)
                        rc = VMR3ReqProcessU(pVM->pUVM, pVCpu->idCpu, false /*fPriorityOnly*/);
                    LogFlow(("dbgfR3CpuWait: VMR3ReqProcess -> %Rrc rcRet=%Rrc\n", rc, rcRet));
                }
                else if (VM_FF_IS_SET(pVM, VM_FF_CHECK_VM_STATE))
                {
                    VMSTATE enmState = VMR3GetState(pVM);
                    switch (enmState)
                    {
                        case VMSTATE_FATAL_ERROR:
                        case VMSTATE_FATAL_ERROR_LS:
                        case VMSTATE_GURU_MEDITATION:
                        case VMSTATE_GURU_MEDITATION_LS:
                            rc = VINF_EM_SUSPEND;
                            break;
                        case VMSTATE_DESTROYING:
                            rc = VINF_EM_TERMINATE;
                            break;
                        default:
                            rc = VERR_DBGF_IPE_1;
                            AssertMsgFailed(("%s\n", VMGetStateName(enmState)));
                    }
                }
                else
                    rc = VINF_SUCCESS;
                if (rc >= VINF_EM_FIRST && rc <= VINF_EM_LAST)
                {
                    switch (rc)
                    {
                        case VINF_EM_DBG_BREAKPOINT:
                        case VINF_EM_DBG_STEPPED:
                        case VINF_EM_DBG_STEP:
                        case VINF_EM_DBG_STOP:
                        case VINF_EM_DBG_EVENT:
                            AssertMsgFailed(("rc=%Rrc\n", rc));
                            break;

                        /* return straight away */
                        case VINF_EM_TERMINATE:
                        case VINF_EM_OFF:
                            LogFlow(("dbgfR3CpuWait: returns %Rrc\n", rc));
                            ASMAtomicWriteBool(&pUVCpu->dbgf.s.fStopped, false);
                            return rc;

                        /* remember return code. */
                        default:
                            AssertReleaseMsgFailed(("rc=%Rrc is not in the switch!\n", rc));
                            RT_FALL_THRU();
                        case VINF_EM_RESET:
                        case VINF_EM_SUSPEND:
                        case VINF_EM_HALT:
                        case VINF_EM_RESUME:
                        case VINF_EM_RESCHEDULE:
                        case VINF_EM_RESCHEDULE_REM:
                        case VINF_EM_RESCHEDULE_RAW:
                            if (rc < rcRet || rcRet == VINF_SUCCESS)
                                rcRet = rc;
                            break;
                    }
                }
                else if (RT_FAILURE(rc))
                {
                    LogFlow(("dbgfR3CpuWait: returns %Rrc\n", rc));
                    ASMAtomicWriteBool(&pUVCpu->dbgf.s.fStopped, false);
                    return rc;
                }
            }
            else if (pVM->dbgf.s.fAttached)
            {
                int rc = VMR3WaitU(pUVCpu);
                if (RT_FAILURE(rc))
                {
                    LogFlow(("dbgfR3CpuWait: returns %Rrc (VMR3WaitU)\n", rc));
                    ASMAtomicWriteBool(&pUVCpu->dbgf.s.fStopped, false);
                    return rc;
                }
            }
            else
            {
                LogFlow(("dbgfR3CpuWait: Debugger detached, continuing normal execution (%Rrc)\n", rcRet));
                ASMAtomicWriteBool(&pUVCpu->dbgf.s.fStopped, false);
                return rcRet;
            }
        }

        /*
         * Process the command.
         */
        VMCPU_FF_CLEAR(pVCpu, VMCPU_FF_DBGF);
        bool            fResumeExecution;
        DBGFCMDDATA     CmdData = pUVCpu->dbgf.s.DbgfCmdData;
        DBGFCMD         enmCmd = dbgfR3CpuGetCmd(pUVCpu);
        int rc = dbgfR3CpuCmd(pVCpu, enmCmd, &CmdData, &fResumeExecution);
        if (fResumeExecution)
        {
            if (RT_FAILURE(rc))
                rcRet = rc;
            else if (    rc >= VINF_EM_FIRST
                     &&  rc <= VINF_EM_LAST
                     &&  (rc < rcRet || rcRet == VINF_SUCCESS))
                rcRet = rc;
            LogFlow(("dbgfR3CpuWait: returns %Rrc\n", rcRet));
            ASMAtomicWriteBool(&pUVCpu->dbgf.s.fStopped, false);
            return rcRet;
        }
    }
}


/**
 * Executes command from debugger.
 *
 * The caller is responsible for waiting or resuming execution based on the
 * value returned in the *pfResumeExecution indicator.
 *
 * @returns VBox status code. (clearify!)
 * @param   pVCpu               The cross context vCPU structure.
 * @param   enmCmd              The command in question.
 * @param   pCmdData            Pointer to the command data.
 * @param   pfResumeExecution   Where to store the resume execution / continue waiting indicator.
 */
static int dbgfR3CpuCmd(PVMCPU pVCpu, DBGFCMD enmCmd, PDBGFCMDDATA pCmdData, bool *pfResumeExecution)
{
    RT_NOREF(pCmdData); /* for later */

    /*
     * The cases in this switch returns directly if no event to send.
     */
    DBGFEVENTTYPE enmEvent;
    DBGFEVENTCTX  enmCtx = DBGFEVENTCTX_INVALID;
    switch (enmCmd)
    {
        /*
         * Halt is answered by an event say that we've halted.
         */
        case DBGFCMD_HALT:
        {
            *pfResumeExecution = false;
            enmEvent = DBGFEVENT_HALT_DONE;
            break;
        }


        /*
         * Resume is not answered, we just resume execution.
         */
        case DBGFCMD_GO:
        {
            pVCpu->dbgf.s.fSingleSteppingRaw = false;
            *pfResumeExecution = true;
            return VINF_SUCCESS;
        }

        /** @todo implement (and define) the rest of the commands. */

        /*
         * Single step, with trace into.
         */
        case DBGFCMD_SINGLE_STEP:
        {
            Log2(("Single step\n"));
            PVM pVM = pVCpu->CTX_SUFF(pVM);
            if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_OVER)
            {
                if (dbgfStepGetCurInstrType(pVM, pVCpu) == DBGFSTEPINSTRTYPE_CALL)
                    pVM->dbgf.s.SteppingFilter.uCallDepth++;
            }
            if (pVM->dbgf.s.SteppingFilter.cMaxSteps > 0)
            {
                pVCpu->dbgf.s.fSingleSteppingRaw = true;
                *pfResumeExecution = true;
                return VINF_EM_DBG_STEP;
            }
            /* Stop after zero steps. Nonsense, but whatever. */
            pVM->dbgf.s.SteppingFilter.idCpu = NIL_VMCPUID;
            *pfResumeExecution = false;
            enmCtx   = dbgfR3FigureEventCtx(pVCpu);
            enmEvent = enmCtx != DBGFEVENTCTX_HYPER ? DBGFEVENT_STEPPED : DBGFEVENT_STEPPED_HYPER;
            break;
        }

        /*
         * Default is to send an invalid command event.
         */
        default:
        {
            *pfResumeExecution = false;
            enmEvent = DBGFEVENT_INVALID_COMMAND;
            break;
        }
    }

    /*
     * Send the pending event.
     */
    Log2(("DBGF: Emulation thread: sending event %d\n", enmEvent));
    int rc = dbgfR3SendEventNoWait(pVCpu->CTX_SUFF(pVM), pVCpu, enmEvent, enmCtx);
    AssertRCStmt(rc, *pfResumeExecution = true);
    return rc;
}


/**
 * @callback_method_impl{FNVMMEMTRENDEZVOUS,
 * EMT rendezvous worker for DBGFR3Attach - only called on one EMT.}
 */
static DECLCALLBACK(VBOXSTRICTRC) dbgfR3Attach(PVM pVM, PVMCPU pVCpu, void *pvUser)
{
    PUVM pUVM = pVM->pUVM;
    int *prcAttach = (int *)pvUser;
    RT_NOREF(pVCpu);

    if (pVM->dbgf.s.fAttached)
    {
        Log(("dbgfR3Attach: Debugger already attached\n"));
        *prcAttach = VERR_DBGF_ALREADY_ATTACHED;
        return VINF_SUCCESS;
    }

    /*
     * The per-CPU bits.
     */
    for (uint32_t i = 0; i < pUVM->cCpus; i++)
    {
        PUVMCPU pUVCpu = &pUVM->aCpus[i];

        pUVCpu->dbgf.s.enmDbgfCmd = DBGFCMD_NO_COMMAND;
        RT_ZERO(pUVCpu->dbgf.s.DbgfCmdData);
    }

    /*
     * Init of the VM -> Debugger communication part living in the global VM structure.
     */
    pUVM->dbgf.s.cDbgEvtMax      = pVM->cCpus * 5 + 10; /* Initial size of event ring, increased when being full. */
    pUVM->dbgf.s.idxDbgEvtWrite  = 0;
    pUVM->dbgf.s.idxDbgEvtRead   = 0;
    pUVM->dbgf.s.hEvtWait        = NIL_RTSEMEVENT;
    pUVM->dbgf.s.hEvtRingBufFull = NIL_RTSEMEVENTMULTI;
    pUVM->dbgf.s.hMtxDbgEvtWr    = NIL_RTSEMFASTMUTEX;
    int rc;
    pUVM->dbgf.s.paDbgEvts       = (PDBGFEVENT)MMR3HeapAllocU(pUVM, MM_TAG_DBGF, pUVM->dbgf.s.cDbgEvtMax * sizeof(DBGFEVENT));
    if (pUVM->dbgf.s.paDbgEvts)
    {
        rc = RTSemEventCreate(&pUVM->dbgf.s.hEvtWait);
        if (RT_SUCCESS(rc))
        {
            rc = RTSemFastMutexCreate(&pUVM->dbgf.s.hMtxDbgEvtWr);
            if (RT_SUCCESS(rc))
            {
                rc = RTSemEventMultiCreate(&pUVM->dbgf.s.hEvtRingBufFull);
                if (RT_SUCCESS(rc))
                {
                    /*
                     * At last, set the attached flag.
                     */
                    ASMAtomicWriteBool(&pVM->dbgf.s.fAttached, true);
                    *prcAttach = VINF_SUCCESS;
                    return VINF_SUCCESS;
                }

                RTSemFastMutexDestroy(pUVM->dbgf.s.hMtxDbgEvtWr);
                pUVM->dbgf.s.hMtxDbgEvtWr = NIL_RTSEMFASTMUTEX;
            }
            RTSemEventDestroy(pUVM->dbgf.s.hEvtWait);
            pUVM->dbgf.s.hEvtWait = NIL_RTSEMEVENT;
        }
    }
    else
        rc = VERR_NO_MEMORY;

    *prcAttach = rc;
    return VINF_SUCCESS;
}


/**
 * Attaches a debugger to the specified VM.
 *
 * Only one debugger at a time.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 */
VMMR3DECL(int) DBGFR3Attach(PUVM pUVM)
{
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);

    /*
     * Call the VM, use EMT rendezvous for serialization.
     */
    int rcAttach = VERR_IPE_UNINITIALIZED_STATUS;
    int rc = VMMR3EmtRendezvous(pVM, VMMEMTRENDEZVOUS_FLAGS_TYPE_ONCE | VMMEMTRENDEZVOUS_FLAGS_PRIORITY, dbgfR3Attach, &rcAttach);
    if (RT_SUCCESS(rc))
        rc = rcAttach;

    return rc;
}


/**
 * @callback_method_impl{FNVMMEMTRENDEZVOUS,
 * EMT rendezvous worker for DBGFR3Detach - called on all EMTs (why?).}
 */
static DECLCALLBACK(VBOXSTRICTRC) dbgfR3Detach(PVM pVM, PVMCPU pVCpu, void *pvUser)
{
    if (pVCpu->idCpu == 0)
    {
        PUVM pUVM = (PUVM)pvUser;

        /*
         * Per-CPU cleanup.
         */
        for (VMCPUID i = 0; i < pUVM->cCpus; i++)
        {
            PUVMCPU pUVCpu = &pUVM->aCpus[i];

            pUVCpu->dbgf.s.enmDbgfCmd = DBGFCMD_NO_COMMAND;
            RT_ZERO(pUVCpu->dbgf.s.DbgfCmdData);
        }

        /*
         * De-init of the VM -> Debugger communication part living in the global VM structure.
         */
        if (pUVM->dbgf.s.paDbgEvts)
        {
            MMR3HeapFree(pUVM->dbgf.s.paDbgEvts);
            pUVM->dbgf.s.paDbgEvts = NULL;
        }

        if (pUVM->dbgf.s.hEvtWait != NIL_RTSEMEVENT)
        {
            RTSemEventDestroy(pUVM->dbgf.s.hEvtWait);
            pUVM->dbgf.s.hEvtWait = NIL_RTSEMEVENT;
        }

        if (pUVM->dbgf.s.hMtxDbgEvtWr != NIL_RTSEMFASTMUTEX)
        {
            RTSemFastMutexDestroy(pUVM->dbgf.s.hMtxDbgEvtWr);
            pUVM->dbgf.s.hMtxDbgEvtWr = NIL_RTSEMFASTMUTEX;
        }

        if (pUVM->dbgf.s.hEvtRingBufFull != NIL_RTSEMEVENTMULTI)
        {
            RTSemEventMultiDestroy(pUVM->dbgf.s.hEvtRingBufFull);
            pUVM->dbgf.s.hEvtRingBufFull = NIL_RTSEMEVENTMULTI;
        }

        pUVM->dbgf.s.cDbgEvtMax      = 0;
        pUVM->dbgf.s.idxDbgEvtWrite  = 0;
        pUVM->dbgf.s.idxDbgEvtRead   = 0;
        pUVM->dbgf.s.hEvtWait        = NIL_RTSEMEVENT;
        pUVM->dbgf.s.hEvtRingBufFull = NIL_RTSEMEVENTMULTI;
        pUVM->dbgf.s.hMtxDbgEvtWr    = NIL_RTSEMFASTMUTEX;

        ASMAtomicWriteBool(&pVM->dbgf.s.fAttached, false);
    }

    return VINF_SUCCESS;
}


/**
 * Detaches a debugger from the specified VM.
 *
 * Caller must be attached to the VM.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 */
VMMR3DECL(int) DBGFR3Detach(PUVM pUVM)
{
    LogFlow(("DBGFR3Detach:\n"));

    /*
     * Validate input. The UVM handle shall be valid, the VM handle might be
     * in the processes of being destroyed already, so deal quietly with that.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    if (!VM_IS_VALID_EXT(pVM))
        return VERR_INVALID_VM_HANDLE;

    /*
     * Check if attached.
     */
    if (!pVM->dbgf.s.fAttached)
        return VERR_DBGF_NOT_ATTACHED;

    return VMMR3EmtRendezvous(pVM, VMMEMTRENDEZVOUS_FLAGS_TYPE_ALL_AT_ONCE | VMMEMTRENDEZVOUS_FLAGS_PRIORITY, dbgfR3Detach, pUVM);
}


/**
 * Wait for a debug event.
 *
 * @returns VBox status code. Will not return VBOX_INTERRUPTED.
 * @param   pUVM        The user mode VM handle.
 * @param   cMillies    Number of millis to wait.
 * @param   pEvent      Where to store the event data.
 */
VMMR3DECL(int) DBGFR3EventWait(PUVM pUVM, RTMSINTERVAL cMillies, PDBGFEVENT pEvent)
{
    /*
     * Check state.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);
    AssertReturn(pVM->dbgf.s.fAttached, VERR_DBGF_NOT_ATTACHED);

    RT_BZERO(pEvent, sizeof(*pEvent));

    /*
     * Wait for an event to arrive if there are none.
     */
    int rc = VINF_SUCCESS;
    uint32_t idxDbgEvtRead = ASMAtomicReadU32(&pUVM->dbgf.s.idxDbgEvtRead);
    if (idxDbgEvtRead == ASMAtomicReadU32(&pUVM->dbgf.s.idxDbgEvtWrite))
    {
        do
        {
            rc = RTSemEventWait(pUVM->dbgf.s.hEvtWait, cMillies);
        } while (   RT_SUCCESS(rc)
                 && idxDbgEvtRead == ASMAtomicReadU32(&pUVM->dbgf.s.idxDbgEvtWrite));
    }

    if (RT_SUCCESS(rc))
    {
        Assert(idxDbgEvtRead != ASMAtomicReadU32(&pUVM->dbgf.s.idxDbgEvtWrite));

        uint32_t const cDbgEvtMax = RT_MAX(1, pUVM->dbgf.s.cDbgEvtMax);
        memcpy(pEvent, &pUVM->dbgf.s.paDbgEvts[idxDbgEvtRead % cDbgEvtMax], sizeof(*pEvent));
        ASMAtomicWriteU32(&pUVM->dbgf.s.idxDbgEvtRead, (idxDbgEvtRead + 1) % cDbgEvtMax);
    }

    Log2(("DBGFR3EventWait: rc=%Rrc (event type %d)\n", rc, pEvent->enmType));
    return rc;
}


/**
 * Halts VM execution.
 *
 * After calling this the VM isn't actually halted till an DBGFEVENT_HALT_DONE
 * arrives. Until that time it's not possible to issue any new commands.
 *
 * @returns VBox status code.
 * @retval  VWRN_DBGF_ALREADY_HALTED if @a idCpu is VMCPUID_ALL and all vCPUs
 *          are halted.
 * @param   pUVM        The user mode VM handle.
 * @param   idCpu       The vCPU to halt, VMCPUID_ALL halts all still running vCPUs.
 */
VMMR3DECL(int) DBGFR3Halt(PUVM pUVM, VMCPUID idCpu)
{
    /*
     * Check state.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);
    AssertReturn(pVM->dbgf.s.fAttached, VERR_DBGF_NOT_ATTACHED);
    AssertReturn(idCpu == VMCPUID_ALL || idCpu < pVM->cCpus, VERR_INVALID_CPU_ID);

    /*
     * Halt the requested CPUs as needed.
     */
    int rc;
    if (idCpu != VMCPUID_ALL)
    {
        PUVMCPU pUVCpu = &pUVM->aCpus[idCpu];
        if (!dbgfR3CpuIsHalted(pUVCpu))
        {
            dbgfR3CpuSetCmdAndNotify(pUVCpu, DBGFCMD_HALT);
            rc = VINF_SUCCESS;
        }
        else
            rc = VWRN_DBGF_ALREADY_HALTED;
    }
    else
    {
        rc = VWRN_DBGF_ALREADY_HALTED;
        for (VMCPUID i = 0; i < pUVM->cCpus; i++)
        {
            PUVMCPU pUVCpu = &pUVM->aCpus[i];
            if (!dbgfR3CpuIsHalted(pUVCpu))
            {
                dbgfR3CpuSetCmdAndNotify(pUVCpu, DBGFCMD_HALT);
                rc = VINF_SUCCESS;
            }
        }
    }

    return rc;
}


/**
 * Checks if any of the specified vCPUs have been halted by the debugger.
 *
 * @returns True if at least one halted vCPUs.
 * @returns False if no halted vCPUs.
 * @param   pUVM        The user mode VM handle.
 * @param   idCpu       The CPU id to check for, VMCPUID_ALL will return true if
 *                      at least a single vCPU is halted in the debugger.
 */
VMMR3DECL(bool) DBGFR3IsHalted(PUVM pUVM, VMCPUID idCpu)
{
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, false);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, false);
    AssertReturn(pVM->dbgf.s.fAttached, false);

    return dbgfR3CpuAreAnyHaltedByCpuId(pUVM, idCpu);
}


/**
 * Checks if the debugger can wait for events or not.
 *
 * This function is only used by lazy, multiplexing debuggers. :-)
 *
 * @returns VBox status code.
 * @retval  VINF_SUCCESS if waitable.
 * @retval  VERR_SEM_OUT_OF_TURN if not waitable.
 * @retval  VERR_INVALID_VM_HANDLE if the VM is being (/ has been) destroyed
 *          (not asserted) or if the handle is invalid (asserted).
 * @retval  VERR_DBGF_NOT_ATTACHED if not attached.
 *
 * @param   pUVM        The user mode VM handle.
 */
VMMR3DECL(int) DBGFR3QueryWaitable(PUVM pUVM)
{
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);

    /* Note! There is a slight race here, unfortunately. */
    PVM pVM = pUVM->pVM;
    if (!RT_VALID_PTR(pVM))
        return VERR_INVALID_VM_HANDLE;
    if (pVM->enmVMState >= VMSTATE_DESTROYING)
        return VERR_INVALID_VM_HANDLE;
    if (!pVM->dbgf.s.fAttached)
        return VERR_DBGF_NOT_ATTACHED;

    /** @todo was: if (!RTSemPongShouldWait(...)) return VERR_SEM_OUT_OF_TURN; */
    return VINF_SUCCESS;
}


/**
 * Resumes VM execution.
 *
 * There is no receipt event on this command.
 *
 * @returns VBox status code.
 * @retval  VWRN_DBGF_ALREADY_RUNNING if the specified vCPUs are all running.
 * @param   pUVM        The user mode VM handle.
 * @param   idCpu       The vCPU to resume, VMCPUID_ALL resumes all still halted vCPUs.
 */
VMMR3DECL(int) DBGFR3Resume(PUVM pUVM, VMCPUID idCpu)
{
    /*
     * Validate input and attachment state.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);
    AssertReturn(pVM->dbgf.s.fAttached, VERR_DBGF_NOT_ATTACHED);

    /*
     * Ping the halted emulation threads, telling them to run.
     */
    int rc = VWRN_DBGF_ALREADY_RUNNING;
    if (idCpu != VMCPUID_ALL)
    {
        PUVMCPU pUVCpu = &pUVM->aCpus[idCpu];
        if (dbgfR3CpuIsHalted(pUVCpu))
        {
            rc = dbgfR3CpuSetCmdAndNotify(pUVCpu, DBGFCMD_GO);
            AssertRC(rc);
        }
    }
    else
    {
        for (VMCPUID i = 0; i < pUVM->cCpus; i++)
        {
            PUVMCPU pUVCpu = &pUVM->aCpus[i];
            if (dbgfR3CpuIsHalted(pUVCpu))
            {
                int rc2 = dbgfR3CpuSetCmdAndNotify(pUVCpu, DBGFCMD_GO);
                AssertRC(rc2);
                if (rc == VWRN_DBGF_ALREADY_RUNNING || RT_FAILURE(rc2))
                    rc = rc2;
            }
        }
    }

    return rc;
}


/**
 * Classifies the current instruction.
 *
 * @returns Type of instruction.
 * @param   pVM                 The cross context VM structure.
 * @param   pVCpu               The current CPU.
 * @thread  EMT(pVCpu)
 */
static DBGFSTEPINSTRTYPE dbgfStepGetCurInstrType(PVM pVM, PVMCPU pVCpu)
{
    /*
     * Read the instruction.
     */
    size_t   cbRead   = 0;
    uint8_t  abOpcode[16] = { 0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0 };
    int rc = PGMR3DbgReadGCPtr(pVM, abOpcode, CPUMGetGuestFlatPC(pVCpu), sizeof(abOpcode) - 1, 0 /*fFlags*/, &cbRead);
    if (RT_SUCCESS(rc))
    {
        /*
         * Do minimal parsing.  No real need to involve the disassembler here.
         */
        uint8_t *pb = abOpcode;
        for (;;)
        {
            switch (*pb++)
            {
                default:
                    return DBGFSTEPINSTRTYPE_OTHER;

                case 0xe8: /* call rel16/32 */
                case 0x9a: /* call farptr */
                case 0xcc: /* int3 */
                case 0xcd: /* int xx */
                // case 0xce: /* into */
                    return DBGFSTEPINSTRTYPE_CALL;

                case 0xc2: /* ret xx */
                case 0xc3: /* ret */
                case 0xca: /* retf xx */
                case 0xcb: /* retf */
                case 0xcf: /* iret */
                    return DBGFSTEPINSTRTYPE_RET;

                case 0xff:
                    if (   ((*pb >> X86_MODRM_REG_SHIFT) & X86_MODRM_REG_SMASK) == 2  /* call indir */
                        || ((*pb >> X86_MODRM_REG_SHIFT) & X86_MODRM_REG_SMASK) == 3) /* call indir-farptr */
                        return DBGFSTEPINSTRTYPE_CALL;
                    return DBGFSTEPINSTRTYPE_OTHER;

                case 0x0f:
                    switch (*pb++)
                    {
                        case 0x05: /* syscall */
                        case 0x34: /* sysenter */
                            return DBGFSTEPINSTRTYPE_CALL;
                        case 0x07: /* sysret */
                        case 0x35: /* sysexit */
                            return DBGFSTEPINSTRTYPE_RET;
                    }
                    break;

                /* Must handle some REX prefixes. So we do all normal prefixes. */
                case 0x40: case 0x41: case 0x42: case 0x43: case 0x44: case 0x45: case 0x46: case 0x47:
                case 0x48: case 0x49: case 0x4a: case 0x4b: case 0x4c: case 0x4d: case 0x4e: case 0x4f:
                    if (!CPUMIsGuestIn64BitCode(pVCpu))
                        return DBGFSTEPINSTRTYPE_OTHER;
                    break;

                case 0x2e: /* CS */
                case 0x36: /* SS */
                case 0x3e: /* DS */
                case 0x26: /* ES */
                case 0x64: /* FS */
                case 0x65: /* GS */
                case 0x66: /* op size */
                case 0x67: /* addr size */
                case 0xf0: /* lock */
                case 0xf2: /* REPNZ */
                case 0xf3: /* REPZ */
                    break;
            }
        }
    }

    return DBGFSTEPINSTRTYPE_INVALID;
}


/**
 * Checks if the stepping has reached a stop point.
 *
 * Called when raising a stepped event.
 *
 * @returns true if the event should be raised, false if we should take one more
 *          step first.
 * @param   pVM         The cross context VM structure.
 * @param   pVCpu       The cross context per CPU structure of the calling EMT.
 * @thread  EMT(pVCpu)
 */
static bool dbgfStepAreWeThereYet(PVM pVM, PVMCPU pVCpu)
{
    /*
     * Check valid pVCpu and that it matches the CPU one stepping.
     */
    if (pVCpu)
    {
        if (pVCpu->idCpu == pVM->dbgf.s.SteppingFilter.idCpu)
        {
            /*
             * Increase the number of steps and see if we've reached the max.
             */
            pVM->dbgf.s.SteppingFilter.cSteps++;
            if (pVM->dbgf.s.SteppingFilter.cSteps < pVM->dbgf.s.SteppingFilter.cMaxSteps)
            {
                /*
                 * Check PC and SP address filtering.
                 */
                if (pVM->dbgf.s.SteppingFilter.fFlags & (DBGF_STEP_F_STOP_ON_ADDRESS | DBGF_STEP_F_STOP_ON_STACK_POP))
                {
                    if (   (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_ON_ADDRESS)
                        && pVM->dbgf.s.SteppingFilter.AddrPc == CPUMGetGuestFlatPC(pVCpu))
                        return true;
                    if (   (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_ON_STACK_POP)
                        &&   CPUMGetGuestFlatSP(pVCpu) - pVM->dbgf.s.SteppingFilter.AddrStackPop
                           < pVM->dbgf.s.SteppingFilter.cbStackPop)
                        return true;
                }

                /*
                 * Do step-over filtering separate from the step-into one.
                 */
                if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_OVER)
                {
                    DBGFSTEPINSTRTYPE enmType = dbgfStepGetCurInstrType(pVM, pVCpu);
                    switch (enmType)
                    {
                        default:
                            if (   pVM->dbgf.s.SteppingFilter.uCallDepth != 0
                                || (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_FILTER_MASK))
                                break;
                            return true;
                        case DBGFSTEPINSTRTYPE_CALL:
                            if (   (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_ON_CALL)
                                && pVM->dbgf.s.SteppingFilter.uCallDepth == 0)
                                return true;
                            pVM->dbgf.s.SteppingFilter.uCallDepth++;
                            break;
                        case DBGFSTEPINSTRTYPE_RET:
                            if (pVM->dbgf.s.SteppingFilter.uCallDepth == 0)
                            {
                                if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_ON_RET)
                                    return true;
                                /* If after return, we use the cMaxStep limit to stop the next time. */
                                if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_AFTER_RET)
                                    pVM->dbgf.s.SteppingFilter.cMaxSteps = pVM->dbgf.s.SteppingFilter.cSteps + 1;
                            }
                            else if (pVM->dbgf.s.SteppingFilter.uCallDepth > 0)
                                pVM->dbgf.s.SteppingFilter.uCallDepth--;
                            break;
                    }
                    return false;
                }
                /*
                 * Filtered step-into.
                 */
                else if (  pVM->dbgf.s.SteppingFilter.fFlags
                         & (DBGF_STEP_F_STOP_ON_CALL | DBGF_STEP_F_STOP_ON_RET | DBGF_STEP_F_STOP_AFTER_RET))
                {
                    DBGFSTEPINSTRTYPE enmType = dbgfStepGetCurInstrType(pVM, pVCpu);
                    switch (enmType)
                    {
                        default:
                            break;
                        case DBGFSTEPINSTRTYPE_CALL:
                            if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_ON_CALL)
                                return true;
                            break;
                        case DBGFSTEPINSTRTYPE_RET:
                            if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_ON_RET)
                                return true;
                            /* If after return, we use the cMaxStep limit to stop the next time. */
                            if (pVM->dbgf.s.SteppingFilter.fFlags & DBGF_STEP_F_STOP_AFTER_RET)
                                pVM->dbgf.s.SteppingFilter.cMaxSteps = pVM->dbgf.s.SteppingFilter.cSteps + 1;
                            break;
                    }
                    return false;
                }
            }
        }
    }

    return true;
}


/**
 * Step Into.
 *
 * A single step event is generated from this command.
 * The current implementation is not reliable, so don't rely on the event coming.
 *
 * @returns VBox status code.
 * @param   pUVM    The user mode VM handle.
 * @param   idCpu   The ID of the CPU to single step on.
 */
VMMR3DECL(int) DBGFR3Step(PUVM pUVM, VMCPUID idCpu)
{
    return DBGFR3StepEx(pUVM, idCpu, DBGF_STEP_F_INTO, NULL, NULL, 0, 1);
}


/**
 * Full fleged step.
 *
 * This extended stepping API allows for doing multiple steps before raising an
 * event, helping implementing step over, step out and other more advanced
 * features.
 *
 * Like the DBGFR3Step() API, this will normally generate a DBGFEVENT_STEPPED or
 * DBGFEVENT_STEPPED_EVENT.  However the stepping may be interrupted by other
 * events, which will abort the stepping.
 *
 * The stop on pop area feature is for safeguarding step out.
 *
 * Please note though, that it will always use stepping and never breakpoints.
 * While this allows for a much greater flexibility it can at times be rather
 * slow.
 *
 * @returns VBox status code.
 * @param   pUVM            The user mode VM handle.
 * @param   idCpu           The ID of the CPU to single step on.
 * @param   fFlags          Flags controlling the stepping, DBGF_STEP_F_XXX.
 *                          Either DBGF_STEP_F_INTO or DBGF_STEP_F_OVER must
 *                          always be specified.
 * @param   pStopPcAddr     Address to stop executing at.  Completely ignored
 *                          unless DBGF_STEP_F_STOP_ON_ADDRESS is specified.
 * @param   pStopPopAddr    Stack address that SP must be lower than when
 *                          performing DBGF_STEP_F_STOP_ON_STACK_POP filtering.
 * @param   cbStopPop       The range starting at @a pStopPopAddr which is
 *                          considered to be within the same thread stack. Note
 *                          that the API allows @a pStopPopAddr and @a cbStopPop
 *                          to form an area that wraps around and it will
 *                          consider the part starting at 0 as included.
 * @param   cMaxSteps       The maximum number of steps to take.  This is to
 *                          prevent stepping for ever, so passing UINT32_MAX is
 *                          not recommended.
 *
 * @remarks The two address arguments must be guest context virtual addresses,
 *          or HMA.  The code doesn't make much of a point of out HMA, though.
 */
VMMR3DECL(int) DBGFR3StepEx(PUVM pUVM, VMCPUID idCpu, uint32_t fFlags, PCDBGFADDRESS pStopPcAddr,
                            PCDBGFADDRESS pStopPopAddr, RTGCUINTPTR cbStopPop, uint32_t cMaxSteps)
{
    /*
     * Check state.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);
    AssertReturn(idCpu < pVM->cCpus, VERR_INVALID_PARAMETER);
    AssertReturn(!(fFlags & ~DBGF_STEP_F_VALID_MASK), VERR_INVALID_FLAGS);
    AssertReturn(RT_BOOL(fFlags & DBGF_STEP_F_INTO) != RT_BOOL(fFlags & DBGF_STEP_F_OVER), VERR_INVALID_FLAGS);
    if (fFlags & DBGF_STEP_F_STOP_ON_ADDRESS)
    {
        AssertReturn(RT_VALID_PTR(pStopPcAddr), VERR_INVALID_POINTER);
        AssertReturn(DBGFADDRESS_IS_VALID(pStopPcAddr), VERR_INVALID_PARAMETER);
        AssertReturn(DBGFADDRESS_IS_VIRT_GC(pStopPcAddr), VERR_INVALID_PARAMETER);
    }
    AssertReturn(!(fFlags & DBGF_STEP_F_STOP_ON_STACK_POP) || RT_VALID_PTR(pStopPopAddr), VERR_INVALID_POINTER);
    if (fFlags & DBGF_STEP_F_STOP_ON_STACK_POP)
    {
        AssertReturn(RT_VALID_PTR(pStopPopAddr), VERR_INVALID_POINTER);
        AssertReturn(DBGFADDRESS_IS_VALID(pStopPopAddr), VERR_INVALID_PARAMETER);
        AssertReturn(DBGFADDRESS_IS_VIRT_GC(pStopPopAddr), VERR_INVALID_PARAMETER);
        AssertReturn(cbStopPop > 0, VERR_INVALID_PARAMETER);
    }

    AssertReturn(pVM->dbgf.s.fAttached, VERR_DBGF_NOT_ATTACHED);
    PUVMCPU pUVCpu = &pUVM->aCpus[idCpu];
    if (RT_LIKELY(dbgfR3CpuIsHalted(pUVCpu)))
    { /* likely */ }
    else
        return VERR_SEM_OUT_OF_TURN;
    Assert(pVM->dbgf.s.SteppingFilter.idCpu == NIL_VMCPUID);

    /*
     * Send the emulation thread a single-step command.
     */
    if (fFlags == DBGF_STEP_F_INTO)
        pVM->dbgf.s.SteppingFilter.idCpu = NIL_VMCPUID;
    else
        pVM->dbgf.s.SteppingFilter.idCpu = idCpu;
    pVM->dbgf.s.SteppingFilter.fFlags = fFlags;
    if (fFlags & DBGF_STEP_F_STOP_ON_ADDRESS)
        pVM->dbgf.s.SteppingFilter.AddrPc = pStopPcAddr->FlatPtr;
    else
        pVM->dbgf.s.SteppingFilter.AddrPc = 0;
    if (fFlags & DBGF_STEP_F_STOP_ON_STACK_POP)
    {
        pVM->dbgf.s.SteppingFilter.AddrStackPop = pStopPopAddr->FlatPtr;
        pVM->dbgf.s.SteppingFilter.cbStackPop   = cbStopPop;
    }
    else
    {
        pVM->dbgf.s.SteppingFilter.AddrStackPop = 0;
        pVM->dbgf.s.SteppingFilter.cbStackPop   = RTGCPTR_MAX;
    }

    pVM->dbgf.s.SteppingFilter.cMaxSteps    = cMaxSteps;
    pVM->dbgf.s.SteppingFilter.cSteps       = 0;
    pVM->dbgf.s.SteppingFilter.uCallDepth   = 0;

    Assert(dbgfR3CpuIsHalted(pUVCpu));
    return dbgfR3CpuSetCmdAndNotify(pUVCpu, DBGFCMD_SINGLE_STEP);
}



/**
 * dbgfR3EventConfigEx argument packet.
 */
typedef struct DBGFR3EVENTCONFIGEXARGS
{
    PCDBGFEVENTCONFIG   paConfigs;
    size_t              cConfigs;
    int                 rc;
} DBGFR3EVENTCONFIGEXARGS;
/** Pointer to a dbgfR3EventConfigEx argument packet. */
typedef DBGFR3EVENTCONFIGEXARGS *PDBGFR3EVENTCONFIGEXARGS;


/**
 * @callback_method_impl{FNVMMEMTRENDEZVOUS, Worker for DBGFR3EventConfigEx.}
 */
static DECLCALLBACK(VBOXSTRICTRC) dbgfR3EventConfigEx(PVM pVM, PVMCPU pVCpu, void *pvUser)
{
    if (pVCpu->idCpu == 0)
    {
        PDBGFR3EVENTCONFIGEXARGS        pArgs = (PDBGFR3EVENTCONFIGEXARGS)pvUser;
        DBGFEVENTCONFIG volatile const *paConfigs = pArgs->paConfigs;
        size_t                          cConfigs  = pArgs->cConfigs;

        /*
         * Apply the changes.
         */
        unsigned cChanges = 0;
        for (uint32_t i = 0; i < cConfigs; i++)
        {
            DBGFEVENTTYPE enmType = paConfigs[i].enmType;
            AssertReturn(enmType >= DBGFEVENT_FIRST_SELECTABLE && enmType < DBGFEVENT_END, VERR_INVALID_PARAMETER);
            if (paConfigs[i].fEnabled)
                cChanges += ASMAtomicBitTestAndSet(&pVM->dbgf.s.bmSelectedEvents, enmType) == false;
            else
                cChanges += ASMAtomicBitTestAndClear(&pVM->dbgf.s.bmSelectedEvents, enmType) == true;
        }

        /*
         * Inform HM about changes.
         */
        if (cChanges > 0)
        {
            if (HMIsEnabled(pVM))
            {
                HMR3NotifyDebugEventChanged(pVM);
                HMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);
            }
            else if (VM_IS_NEM_ENABLED(pVM))
            {
                NEMR3NotifyDebugEventChanged(pVM);
                NEMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);
            }
        }
    }
    else if (HMIsEnabled(pVM))
        HMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);
    else if (VM_IS_NEM_ENABLED(pVM))
        NEMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);

    return VINF_SUCCESS;
}


/**
 * Configures (enables/disables) multiple selectable debug events.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 * @param   paConfigs   The event to configure and their new state.
 * @param   cConfigs    Number of entries in @a paConfigs.
 */
VMMR3DECL(int) DBGFR3EventConfigEx(PUVM pUVM, PCDBGFEVENTCONFIG paConfigs, size_t cConfigs)
{
    /*
     * Validate input.
     */
    size_t i = cConfigs;
    while (i-- > 0)
    {
        AssertReturn(paConfigs[i].enmType >= DBGFEVENT_FIRST_SELECTABLE, VERR_INVALID_PARAMETER);
        AssertReturn(paConfigs[i].enmType <  DBGFEVENT_END, VERR_INVALID_PARAMETER);
    }
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);

    /*
     * Apply the changes in EMT(0) and rendezvous with the other CPUs so they
     * can sync their data and execution with new debug state.
     */
    DBGFR3EVENTCONFIGEXARGS Args = { paConfigs, cConfigs, VINF_SUCCESS };
    int rc = VMMR3EmtRendezvous(pVM, VMMEMTRENDEZVOUS_FLAGS_TYPE_ASCENDING | VMMEMTRENDEZVOUS_FLAGS_PRIORITY,
                                dbgfR3EventConfigEx, &Args);
    if (RT_SUCCESS(rc))
        rc = Args.rc;
    return rc;
}


/**
 * Enables or disables a selectable debug event.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 * @param   enmEvent    The selectable debug event.
 * @param   fEnabled    The new state.
 */
VMMR3DECL(int) DBGFR3EventConfig(PUVM pUVM, DBGFEVENTTYPE enmEvent, bool fEnabled)
{
    /*
     * Convert to an array call.
     */
    DBGFEVENTCONFIG EvtCfg = { enmEvent, fEnabled };
    return DBGFR3EventConfigEx(pUVM, &EvtCfg, 1);
}


/**
 * Checks if the given selectable event is enabled.
 *
 * @returns true if enabled, false if not or invalid input.
 * @param   pUVM        The user mode VM handle.
 * @param   enmEvent    The selectable debug event.
 * @sa      DBGFR3EventQuery
 */
VMMR3DECL(bool) DBGFR3EventIsEnabled(PUVM pUVM, DBGFEVENTTYPE enmEvent)
{
    /*
     * Validate input.
     */
    AssertReturn(   enmEvent >= DBGFEVENT_HALT_DONE
                 && enmEvent <  DBGFEVENT_END, false);
    Assert(   enmEvent >= DBGFEVENT_FIRST_SELECTABLE
           || enmEvent == DBGFEVENT_BREAKPOINT
           || enmEvent == DBGFEVENT_BREAKPOINT_IO
           || enmEvent == DBGFEVENT_BREAKPOINT_MMIO);

    UVM_ASSERT_VALID_EXT_RETURN(pUVM, false);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, false);

    /*
     * Check the event status.
     */
    return ASMBitTest(&pVM->dbgf.s.bmSelectedEvents, enmEvent);
}


/**
 * Queries the status of a set of events.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 * @param   paConfigs   The events to query and where to return the state.
 * @param   cConfigs    The number of elements in @a paConfigs.
 * @sa      DBGFR3EventIsEnabled, DBGF_IS_EVENT_ENABLED
 */
VMMR3DECL(int) DBGFR3EventQuery(PUVM pUVM, PDBGFEVENTCONFIG paConfigs, size_t cConfigs)
{
    /*
     * Validate input.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);

    for (size_t i = 0; i < cConfigs; i++)
    {
        DBGFEVENTTYPE enmType = paConfigs[i].enmType;
        AssertReturn(   enmType >= DBGFEVENT_HALT_DONE
                     && enmType <  DBGFEVENT_END, VERR_INVALID_PARAMETER);
        Assert(   enmType >= DBGFEVENT_FIRST_SELECTABLE
               || enmType == DBGFEVENT_BREAKPOINT
               || enmType == DBGFEVENT_BREAKPOINT_IO
               || enmType == DBGFEVENT_BREAKPOINT_MMIO);
        paConfigs[i].fEnabled = ASMBitTest(&pVM->dbgf.s.bmSelectedEvents, paConfigs[i].enmType);
    }

    return VINF_SUCCESS;
}


/**
 * dbgfR3InterruptConfigEx argument packet.
 */
typedef struct DBGFR3INTERRUPTCONFIGEXARGS
{
    PCDBGFINTERRUPTCONFIG   paConfigs;
    size_t                  cConfigs;
    int                     rc;
} DBGFR3INTERRUPTCONFIGEXARGS;
/** Pointer to a dbgfR3InterruptConfigEx argument packet. */
typedef DBGFR3INTERRUPTCONFIGEXARGS *PDBGFR3INTERRUPTCONFIGEXARGS;

/**
 * @callback_method_impl{FNVMMEMTRENDEZVOUS,
 *      Worker for DBGFR3InterruptConfigEx.}
 */
static DECLCALLBACK(VBOXSTRICTRC) dbgfR3InterruptConfigEx(PVM pVM, PVMCPU pVCpu, void *pvUser)
{
    if (pVCpu->idCpu == 0)
    {
        PDBGFR3INTERRUPTCONFIGEXARGS    pArgs = (PDBGFR3INTERRUPTCONFIGEXARGS)pvUser;
        PCDBGFINTERRUPTCONFIG           paConfigs = pArgs->paConfigs;
        size_t                          cConfigs  = pArgs->cConfigs;

        /*
         * Apply the changes.
         */
        bool fChanged = false;
        bool fThis;
        for (uint32_t i = 0; i < cConfigs; i++)
        {
            /*
             * Hardware interrupts.
             */
            if (paConfigs[i].enmHardState == DBGFINTERRUPTSTATE_ENABLED)
            {
                fChanged |= fThis = ASMAtomicBitTestAndSet(&pVM->dbgf.s.bmHardIntBreakpoints, paConfigs[i].iInterrupt) == false;
                if (fThis)
                {
                    Assert(pVM->dbgf.s.cHardIntBreakpoints < 256);
                    pVM->dbgf.s.cHardIntBreakpoints++;
                }
            }
            else if (paConfigs[i].enmHardState == DBGFINTERRUPTSTATE_DISABLED)
            {
                fChanged |= fThis = ASMAtomicBitTestAndClear(&pVM->dbgf.s.bmHardIntBreakpoints, paConfigs[i].iInterrupt) == true;
                if (fThis)
                {
                    Assert(pVM->dbgf.s.cHardIntBreakpoints > 0);
                    pVM->dbgf.s.cHardIntBreakpoints--;
                }
            }

            /*
             * Software interrupts.
             */
            if (paConfigs[i].enmHardState == DBGFINTERRUPTSTATE_ENABLED)
            {
                fChanged |= fThis = ASMAtomicBitTestAndSet(&pVM->dbgf.s.bmSoftIntBreakpoints, paConfigs[i].iInterrupt) == false;
                if (fThis)
                {
                    Assert(pVM->dbgf.s.cSoftIntBreakpoints < 256);
                    pVM->dbgf.s.cSoftIntBreakpoints++;
                }
            }
            else if (paConfigs[i].enmSoftState == DBGFINTERRUPTSTATE_DISABLED)
            {
                fChanged |= fThis = ASMAtomicBitTestAndClear(&pVM->dbgf.s.bmSoftIntBreakpoints, paConfigs[i].iInterrupt) == true;
                if (fThis)
                {
                    Assert(pVM->dbgf.s.cSoftIntBreakpoints > 0);
                    pVM->dbgf.s.cSoftIntBreakpoints--;
                }
            }
        }

        /*
         * Update the event bitmap entries.
         */
        if (pVM->dbgf.s.cHardIntBreakpoints > 0)
            fChanged |= ASMAtomicBitTestAndSet(&pVM->dbgf.s.bmSelectedEvents, DBGFEVENT_INTERRUPT_HARDWARE) == false;
        else
            fChanged |= ASMAtomicBitTestAndClear(&pVM->dbgf.s.bmSelectedEvents, DBGFEVENT_INTERRUPT_HARDWARE) == true;

        if (pVM->dbgf.s.cSoftIntBreakpoints > 0)
            fChanged |= ASMAtomicBitTestAndSet(&pVM->dbgf.s.bmSelectedEvents, DBGFEVENT_INTERRUPT_SOFTWARE) == false;
        else
            fChanged |= ASMAtomicBitTestAndClear(&pVM->dbgf.s.bmSelectedEvents, DBGFEVENT_INTERRUPT_SOFTWARE) == true;

        /*
         * Inform HM about changes.
         */
        if (fChanged)
        {
            if (HMIsEnabled(pVM))
            {
                HMR3NotifyDebugEventChanged(pVM);
                HMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);
            }
            else if (VM_IS_NEM_ENABLED(pVM))
            {
                NEMR3NotifyDebugEventChanged(pVM);
                NEMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);
            }
        }
    }
    else if (HMIsEnabled(pVM))
        HMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);
    else if (VM_IS_NEM_ENABLED(pVM))
        NEMR3NotifyDebugEventChangedPerCpu(pVM, pVCpu);

    return VINF_SUCCESS;
}


/**
 * Changes
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 * @param   paConfigs   The events to query and where to return the state.
 * @param   cConfigs    The number of elements in @a paConfigs.
 * @sa      DBGFR3InterruptConfigHardware, DBGFR3InterruptConfigSoftware
 */
VMMR3DECL(int) DBGFR3InterruptConfigEx(PUVM pUVM, PCDBGFINTERRUPTCONFIG paConfigs, size_t cConfigs)
{
    /*
     * Validate input.
     */
    size_t i = cConfigs;
    while (i-- > 0)
    {
        AssertReturn(paConfigs[i].enmHardState <= DBGFINTERRUPTSTATE_DONT_TOUCH, VERR_INVALID_PARAMETER);
        AssertReturn(paConfigs[i].enmSoftState <= DBGFINTERRUPTSTATE_DONT_TOUCH, VERR_INVALID_PARAMETER);
    }

    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);

    /*
     * Apply the changes in EMT(0) and rendezvous with the other CPUs so they
     * can sync their data and execution with new debug state.
     */
    DBGFR3INTERRUPTCONFIGEXARGS Args = { paConfigs, cConfigs, VINF_SUCCESS };
    int rc = VMMR3EmtRendezvous(pVM, VMMEMTRENDEZVOUS_FLAGS_TYPE_ASCENDING | VMMEMTRENDEZVOUS_FLAGS_PRIORITY,
                                dbgfR3InterruptConfigEx, &Args);
    if (RT_SUCCESS(rc))
        rc = Args.rc;
    return rc;
}


/**
 * Configures interception of a hardware interrupt.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 * @param   iInterrupt  The interrupt number.
 * @param   fEnabled    Whether interception is enabled or not.
 * @sa      DBGFR3InterruptSoftwareConfig, DBGFR3InterruptConfigEx
 */
VMMR3DECL(int) DBGFR3InterruptHardwareConfig(PUVM pUVM, uint8_t iInterrupt, bool fEnabled)
{
    /*
     * Convert to DBGFR3InterruptConfigEx call.
     */
    DBGFINTERRUPTCONFIG IntCfg = { iInterrupt, (uint8_t)fEnabled, DBGFINTERRUPTSTATE_DONT_TOUCH };
    return DBGFR3InterruptConfigEx(pUVM, &IntCfg, 1);
}


/**
 * Configures interception of a software interrupt.
 *
 * @returns VBox status code.
 * @param   pUVM        The user mode VM handle.
 * @param   iInterrupt  The interrupt number.
 * @param   fEnabled    Whether interception is enabled or not.
 * @sa      DBGFR3InterruptHardwareConfig, DBGFR3InterruptConfigEx
 */
VMMR3DECL(int) DBGFR3InterruptSoftwareConfig(PUVM pUVM, uint8_t iInterrupt, bool fEnabled)
{
    /*
     * Convert to DBGFR3InterruptConfigEx call.
     */
    DBGFINTERRUPTCONFIG IntCfg = { iInterrupt, DBGFINTERRUPTSTATE_DONT_TOUCH, (uint8_t)fEnabled };
    return DBGFR3InterruptConfigEx(pUVM, &IntCfg, 1);
}


/**
 * Checks whether interception is enabled for a hardware interrupt.
 *
 * @returns true if enabled, false if not or invalid input.
 * @param   pUVM        The user mode VM handle.
 * @param   iInterrupt  The interrupt number.
 * @sa      DBGFR3InterruptSoftwareIsEnabled, DBGF_IS_HARDWARE_INT_ENABLED,
 *          DBGF_IS_SOFTWARE_INT_ENABLED
 */
VMMR3DECL(int) DBGFR3InterruptHardwareIsEnabled(PUVM pUVM, uint8_t iInterrupt)
{
    /*
     * Validate input.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, false);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, false);

    /*
     * Check it.
     */
    return ASMBitTest(&pVM->dbgf.s.bmHardIntBreakpoints, iInterrupt);
}


/**
 * Checks whether interception is enabled for a software interrupt.
 *
 * @returns true if enabled, false if not or invalid input.
 * @param   pUVM        The user mode VM handle.
 * @param   iInterrupt  The interrupt number.
 * @sa      DBGFR3InterruptHardwareIsEnabled, DBGF_IS_SOFTWARE_INT_ENABLED,
 *          DBGF_IS_HARDWARE_INT_ENABLED,
 */
VMMR3DECL(int) DBGFR3InterruptSoftwareIsEnabled(PUVM pUVM, uint8_t iInterrupt)
{
    /*
     * Validate input.
     */
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, false);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, false);

    /*
     * Check it.
     */
    return ASMBitTest(&pVM->dbgf.s.bmSoftIntBreakpoints, iInterrupt);
}



/**
 * Call this to single step programmatically.
 *
 * You must pass down the return code to the EM loop! That's
 * where the actual single stepping take place (at least in the
 * current implementation).
 *
 * @returns VINF_EM_DBG_STEP
 *
 * @param   pVCpu       The cross context virtual CPU structure.
 *
 * @thread  VCpu EMT
 * @internal
 */
VMMR3_INT_DECL(int) DBGFR3PrgStep(PVMCPU pVCpu)
{
    VMCPU_ASSERT_EMT(pVCpu);

    pVCpu->dbgf.s.fSingleSteppingRaw = true;
    return VINF_EM_DBG_STEP;
}


/**
 * Inject an NMI into a running VM (only VCPU 0!)
 *
 * @returns VBox status code.
 * @param   pUVM    The user mode VM structure.
 * @param   idCpu   The ID of the CPU to inject the NMI on.
 */
VMMR3DECL(int) DBGFR3InjectNMI(PUVM pUVM, VMCPUID idCpu)
{
    UVM_ASSERT_VALID_EXT_RETURN(pUVM, VERR_INVALID_VM_HANDLE);
    PVM pVM = pUVM->pVM;
    VM_ASSERT_VALID_EXT_RETURN(pVM, VERR_INVALID_VM_HANDLE);
    AssertReturn(idCpu < pVM->cCpus, VERR_INVALID_CPU_ID);

    /** @todo Implement generic NMI injection. */
    /** @todo NEM: NMI injection   */
    if (!HMIsEnabled(pVM))
        return VERR_NOT_SUP_BY_NEM;

    VMCPU_FF_SET(pVM->apCpusR3[idCpu], VMCPU_FF_INTERRUPT_NMI);
    return VINF_SUCCESS;
}