xref: /openbmc/qemu/tools/i386/qemu-vmsr-helper.c (revision 83340193) 
1 /*
2  * Privileged RAPL MSR helper commands for QEMU
3  *
4  * Copyright (C) 2024 Red Hat, Inc. <aharivel@redhat.com>
5  *
6  * Author: Anthony Harivel <aharivel@redhat.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; under version 2 of the License.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include "qemu/osdep.h"
22 #include <getopt.h>
23 #include <stdbool.h>
24 #include <sys/ioctl.h>
25 #ifdef CONFIG_LIBCAP_NG
26 #include <cap-ng.h>
27 #endif
28 #include <pwd.h>
29 #include <grp.h>
30 
31 #include "qemu/help-texts.h"
32 #include "qapi/error.h"
33 #include "qemu/cutils.h"
34 #include "qemu/main-loop.h"
35 #include "qemu/module.h"
36 #include "qemu/error-report.h"
37 #include "qemu/config-file.h"
38 #include "qemu-version.h"
39 #include "qapi/error.h"
40 #include "qemu/error-report.h"
41 #include "qemu/log.h"
42 #include "qemu/systemd.h"
43 #include "io/channel.h"
44 #include "io/channel-socket.h"
45 #include "trace/control.h"
46 #include "qemu-version.h"
47 #include "rapl-msr-index.h"
48 
49 #define MSR_PATH_TEMPLATE "/dev/cpu/%u/msr"
50 
51 static char *socket_path;
52 static char *pidfile;
53 static enum { RUNNING, TERMINATE, TERMINATING } state;
54 static QIOChannelSocket *server_ioc;
55 static int server_watch;
56 static int num_active_sockets = 1;
57 
58 #ifdef CONFIG_LIBCAP_NG
59 static int uid = -1;
60 static int gid = -1;
61 #endif
62 
63 static void compute_default_paths(void)
64 {
65     g_autofree char *state = qemu_get_local_state_dir();
66 
67     socket_path = g_build_filename(state, "run", "qemu-vmsr-helper.sock", NULL);
68     pidfile = g_build_filename(state, "run", "qemu-vmsr-helper.pid", NULL);
69 }
70 
71 static int is_intel_processor(void)
72 {
73     int result;
74     int ebx, ecx, edx;
75 
76     /* Execute CPUID instruction with eax=0 (basic identification) */
77     asm volatile (
78         "cpuid"
79         : "=b" (ebx), "=c" (ecx), "=d" (edx)
80         : "a" (0)
81     );
82 
83     /*
84      *  Check if processor is "GenuineIntel"
85      *  0x756e6547 = "Genu"
86      *  0x49656e69 = "ineI"
87      *  0x6c65746e = "ntel"
88      */
89     result = (ebx == 0x756e6547) && (edx == 0x49656e69) && (ecx == 0x6c65746e);
90 
91     return result;
92 }
93 
94 static int is_rapl_enabled(void)
95 {
96     const char *path = "/sys/class/powercap/intel-rapl/enabled";
97     FILE *file = fopen(path, "r");
98     int value = 0;
99 
100     if (file != NULL) {
101         if (fscanf(file, "%d", &value) != 1) {
102             error_report("INTEL RAPL not enabled");
103         }
104         fclose(file);
105     } else {
106         error_report("Error opening %s", path);
107     }
108 
109     return value;
110 }
111 
112 /*
113  * Check if the TID that request the MSR read
114  * belongs to the peer. It be should a TID of a vCPU.
115  */
116 static bool is_tid_present(pid_t pid, pid_t tid)
117 {
118     g_autofree char *tidPath = g_strdup_printf("/proc/%d/task/%d", pid, tid);
119 
120     /* Check if the TID directory exists within the PID directory */
121     if (access(tidPath, F_OK) == 0) {
122         return true;
123     }
124 
125     error_report("Failed to open /proc at %s", tidPath);
126     return false;
127 }
128 
129 /*
130  * Only the RAPL MSR in target/i386/cpu.h are allowed
131  */
132 static bool is_msr_allowed(uint32_t reg)
133 {
134     switch (reg) {
135     case MSR_RAPL_POWER_UNIT:
136     case MSR_PKG_POWER_LIMIT:
137     case MSR_PKG_ENERGY_STATUS:
138     case MSR_PKG_POWER_INFO:
139         return true;
140     default:
141         return false;
142     }
143 }
144 
145 static uint64_t vmsr_read_msr(uint32_t msr_register, unsigned int cpu_id)
146 {
147     int fd;
148     uint64_t result = 0;
149 
150     g_autofree char *path = g_strdup_printf(MSR_PATH_TEMPLATE, cpu_id);
151 
152     fd = open(path, O_RDONLY);
153     if (fd < 0) {
154         error_report("Failed to open MSR file at %s", path);
155         return result;
156     }
157 
158     if (pread(fd, &result, sizeof(result), msr_register) != sizeof(result)) {
159         error_report("Failed to read MSR");
160         result = 0;
161     }
162 
163     close(fd);
164     return result;
165 }
166 
167 static void usage(const char *name)
168 {
169     (printf) (
170 "Usage: %s [OPTIONS] FILE\n"
171 "Virtual RAPL MSR helper program for QEMU\n"
172 "\n"
173 "  -h, --help                display this help and exit\n"
174 "  -V, --version             output version information and exit\n"
175 "\n"
176 "  -d, --daemon              run in the background\n"
177 "  -f, --pidfile=PATH        PID file when running as a daemon\n"
178 "                            (default '%s')\n"
179 "  -k, --socket=PATH         path to the unix socket\n"
180 "                            (default '%s')\n"
181 "  -T, --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
182 "                            specify tracing options\n"
183 #ifdef CONFIG_LIBCAP_NG
184 "  -u, --user=USER           user to drop privileges to\n"
185 "  -g, --group=GROUP         group to drop privileges to\n"
186 #endif
187 "\n"
188 QEMU_HELP_BOTTOM "\n"
189     , name, pidfile, socket_path);
190 }
191 
192 static void version(const char *name)
193 {
194     printf(
195 "%s " QEMU_FULL_VERSION "\n"
196 "Written by Anthony Harivel.\n"
197 "\n"
198 QEMU_COPYRIGHT "\n"
199 "This is free software; see the source for copying conditions.  There is NO\n"
200 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
201     , name);
202 }
203 
204 typedef struct VMSRHelperClient {
205     QIOChannelSocket *ioc;
206     Coroutine *co;
207 } VMSRHelperClient;
208 
209 static void coroutine_fn vh_co_entry(void *opaque)
210 {
211     VMSRHelperClient *client = opaque;
212     Error *local_err = NULL;
213     unsigned int peer_pid;
214     uint32_t request[3];
215     uint64_t vmsr;
216     int r;
217 
218     qio_channel_set_blocking(QIO_CHANNEL(client->ioc),
219                              false, NULL);
220 
221     qio_channel_set_follow_coroutine_ctx(QIO_CHANNEL(client->ioc), true);
222 
223     /*
224      * Check peer credentials
225      */
226     r = qio_channel_get_peerpid(QIO_CHANNEL(client->ioc),
227                                 &peer_pid,
228                                 &local_err);
229     if (r < 0) {
230         error_report_err(local_err);
231         goto out;
232     }
233 
234     while (r < 0) {
235         /*
236          * Read the requested MSR
237          * Only RAPL MSR in rapl-msr-index.h is allowed
238          */
239         r = qio_channel_read_all(QIO_CHANNEL(client->ioc),
240                                 (char *) &request, sizeof(request), &local_err);
241         if (r < 0) {
242             error_report_err(local_err);
243             break;
244         }
245 
246         if (!is_msr_allowed(request[0])) {
247             error_report("Requested unallowed msr: %d", request[0]);
248             break;
249         }
250 
251         vmsr = vmsr_read_msr(request[0], request[1]);
252 
253         if (!is_tid_present(peer_pid, request[2])) {
254             error_report("Requested TID not in peer PID: %d %d",
255                 peer_pid, request[2]);
256             vmsr = 0;
257         }
258 
259         r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
260                                   (char *) &vmsr,
261                                   sizeof(vmsr),
262                                   &local_err);
263         if (r < 0) {
264             error_report_err(local_err);
265             break;
266         }
267     }
268 out:
269     object_unref(OBJECT(client->ioc));
270     g_free(client);
271 }
272 
273 static gboolean accept_client(QIOChannel *ioc,
274                               GIOCondition cond,
275                               gpointer opaque)
276 {
277     QIOChannelSocket *cioc;
278     VMSRHelperClient *vmsrh;
279 
280     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
281                                      NULL);
282     if (!cioc) {
283         return TRUE;
284     }
285 
286     vmsrh = g_new(VMSRHelperClient, 1);
287     vmsrh->ioc = cioc;
288     vmsrh->co = qemu_coroutine_create(vh_co_entry, vmsrh);
289     qemu_coroutine_enter(vmsrh->co);
290 
291     return TRUE;
292 }
293 
294 static void termsig_handler(int signum)
295 {
296     qatomic_cmpxchg(&state, RUNNING, TERMINATE);
297     qemu_notify_event();
298 }
299 
300 static void close_server_socket(void)
301 {
302     assert(server_ioc);
303 
304     g_source_remove(server_watch);
305     server_watch = -1;
306     object_unref(OBJECT(server_ioc));
307     num_active_sockets--;
308 }
309 
310 #ifdef CONFIG_LIBCAP_NG
311 static int drop_privileges(void)
312 {
313     /* clear all capabilities */
314     capng_clear(CAPNG_SELECT_BOTH);
315 
316     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
317                      CAP_SYS_RAWIO) < 0) {
318         return -1;
319     }
320 
321     return 0;
322 }
323 #endif
324 
325 int main(int argc, char **argv)
326 {
327     const char *sopt = "hVk:f:dT:u:g:vq";
328     struct option lopt[] = {
329         { "help", no_argument, NULL, 'h' },
330         { "version", no_argument, NULL, 'V' },
331         { "socket", required_argument, NULL, 'k' },
332         { "pidfile", required_argument, NULL, 'f' },
333         { "daemon", no_argument, NULL, 'd' },
334         { "trace", required_argument, NULL, 'T' },
335         { "verbose", no_argument, NULL, 'v' },
336         { NULL, 0, NULL, 0 }
337     };
338     int opt_ind = 0;
339     int ch;
340     Error *local_err = NULL;
341     bool daemonize = false;
342     bool pidfile_specified = false;
343     bool socket_path_specified = false;
344     unsigned socket_activation;
345 
346     struct sigaction sa_sigterm;
347     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
348     sa_sigterm.sa_handler = termsig_handler;
349     sigaction(SIGTERM, &sa_sigterm, NULL);
350     sigaction(SIGINT, &sa_sigterm, NULL);
351     sigaction(SIGHUP, &sa_sigterm, NULL);
352 
353     signal(SIGPIPE, SIG_IGN);
354 
355     error_init(argv[0]);
356     module_call_init(MODULE_INIT_TRACE);
357     module_call_init(MODULE_INIT_QOM);
358     qemu_add_opts(&qemu_trace_opts);
359     qemu_init_exec_dir(argv[0]);
360 
361     compute_default_paths();
362 
363     /*
364      * Sanity check
365      * 1. cpu must be Intel cpu
366      * 2. RAPL must be enabled
367      */
368     if (!is_intel_processor()) {
369         error_report("error: CPU is not INTEL cpu");
370         exit(EXIT_FAILURE);
371     }
372 
373     if (!is_rapl_enabled()) {
374         error_report("error: RAPL driver not enable");
375         exit(EXIT_FAILURE);
376     }
377 
378     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
379         switch (ch) {
380         case 'k':
381             g_free(socket_path);
382             socket_path = g_strdup(optarg);
383             socket_path_specified = true;
384             if (socket_path[0] != '/') {
385                 error_report("socket path must be absolute");
386                 exit(EXIT_FAILURE);
387             }
388             break;
389         case 'f':
390             g_free(pidfile);
391             pidfile = g_strdup(optarg);
392             pidfile_specified = true;
393             break;
394 #ifdef CONFIG_LIBCAP_NG
395         case 'u': {
396             unsigned long res;
397             struct passwd *userinfo = getpwnam(optarg);
398             if (userinfo) {
399                 uid = userinfo->pw_uid;
400             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
401                        (uid_t)res == res) {
402                 uid = res;
403             } else {
404                 error_report("invalid user '%s'", optarg);
405                 exit(EXIT_FAILURE);
406             }
407             break;
408         }
409         case 'g': {
410             unsigned long res;
411             struct group *groupinfo = getgrnam(optarg);
412             if (groupinfo) {
413                 gid = groupinfo->gr_gid;
414             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
415                        (gid_t)res == res) {
416                 gid = res;
417             } else {
418                 error_report("invalid group '%s'", optarg);
419                 exit(EXIT_FAILURE);
420             }
421             break;
422         }
423 #else
424         case 'u':
425         case 'g':
426             error_report("-%c not supported by this %s", ch, argv[0]);
427             exit(1);
428 #endif
429         case 'd':
430             daemonize = true;
431             break;
432         case 'T':
433             trace_opt_parse(optarg);
434             break;
435         case 'V':
436             version(argv[0]);
437             exit(EXIT_SUCCESS);
438             break;
439         case 'h':
440             usage(argv[0]);
441             exit(EXIT_SUCCESS);
442             break;
443         case '?':
444             error_report("Try `%s --help' for more information.", argv[0]);
445             exit(EXIT_FAILURE);
446         }
447     }
448 
449     if (!trace_init_backends()) {
450         exit(EXIT_FAILURE);
451     }
452     trace_init_file();
453     qemu_set_log(LOG_TRACE, &error_fatal);
454 
455     socket_activation = check_socket_activation();
456     if (socket_activation == 0) {
457         SocketAddress saddr;
458         saddr = (SocketAddress){
459             .type = SOCKET_ADDRESS_TYPE_UNIX,
460             .u.q_unix.path = socket_path,
461         };
462         server_ioc = qio_channel_socket_new();
463         if (qio_channel_socket_listen_sync(server_ioc, &saddr,
464                                            1, &local_err) < 0) {
465             object_unref(OBJECT(server_ioc));
466             error_report_err(local_err);
467             return 1;
468         }
469     } else {
470         /* Using socket activation - check user didn't use -p etc. */
471         if (socket_path_specified) {
472             error_report("Unix socket can't be set when"
473                          "using socket activation");
474             exit(EXIT_FAILURE);
475         }
476 
477         /* Can only listen on a single socket.  */
478         if (socket_activation > 1) {
479             error_report("%s does not support socket activation"
480                          "with LISTEN_FDS > 1",
481                         argv[0]);
482             exit(EXIT_FAILURE);
483         }
484         server_ioc = qio_channel_socket_new_fd(FIRST_SOCKET_ACTIVATION_FD,
485                                                &local_err);
486         if (server_ioc == NULL) {
487             error_reportf_err(local_err,
488                               "Failed to use socket activation: ");
489             exit(EXIT_FAILURE);
490         }
491     }
492 
493     qemu_init_main_loop(&error_fatal);
494 
495     server_watch = qio_channel_add_watch(QIO_CHANNEL(server_ioc),
496                                          G_IO_IN,
497                                          accept_client,
498                                          NULL, NULL);
499 
500     if (daemonize) {
501         if (daemon(0, 0) < 0) {
502             error_report("Failed to daemonize: %s", strerror(errno));
503             exit(EXIT_FAILURE);
504         }
505     }
506 
507     if (daemonize || pidfile_specified) {
508         qemu_write_pidfile(pidfile, &error_fatal);
509     }
510 
511 #ifdef CONFIG_LIBCAP_NG
512     if (drop_privileges() < 0) {
513         error_report("Failed to drop privileges: %s", strerror(errno));
514         exit(EXIT_FAILURE);
515     }
516 #endif
517 
518     info_report("Listening on %s", socket_path);
519 
520     state = RUNNING;
521     do {
522         main_loop_wait(false);
523         if (state == TERMINATE) {
524             state = TERMINATING;
525             close_server_socket();
526         }
527     } while (num_active_sockets > 0);
528 
529     exit(EXIT_SUCCESS);
530 }
531