4 files changed, 46 insertions, 13 deletions

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index a7350519c63f..21c164b8f9db 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1691,17 +1691,15 @@ int cmd_kvm(int argc, const char **argv, const char *prefix __maybe_unused)
                 OPT_END()
         };
 
-
-        const char * const kvm_usage[] = {
-                "perf kvm [<options>] {top|record|report|diff|buildid-list|stat}",
-                NULL
-        };
+        const char *const kvm_subcommands[] = { "top", "record", "report", "diff",
+                                                "buildid-list", "stat", NULL };
+        const char *kvm_usage[] = { NULL, NULL };
 
         perf_host  = 0;
         perf_guest = 1;
 
-        argc = parse_options(argc, argv, kvm_options, kvm_usage,
-                        PARSE_OPT_STOP_AT_NON_OPTION);
+        argc = parse_options_subcommand(argc, argv, kvm_options, kvm_subcommands, kvm_usage,
+                                        PARSE_OPT_STOP_AT_NON_OPTION);
         if (!argc)
                 usage_with_options(kvm_usage, kvm_options);
 
diff --git a/tools/perf/perf-completion.sh b/tools/perf/perf-completion.sh
index 496e2abb5482..ae3a57694b6b 100644
--- a/tools/perf/perf-completion.sh
+++ b/tools/perf/perf-completion.sh
@@ -123,7 +123,7 @@ __perf_main ()
                 __perfcomp_colon "$evts" "$cur"
         # List subcommands for 'perf kvm'
         elif [[ $prev == "kvm" ]]; then
-                subcmds="top record report diff buildid-list stat"
+                subcmds=$($cmd $prev --list-cmds)
                 __perfcomp_colon "$subcmds" "$cur"
         # List long option names
         elif [[ $cur == --* ]];  then
diff --git a/tools/perf/util/parse-options.c b/tools/perf/util/parse-options.c
index d22e3f8017dc..bf48092983c6 100644
--- a/tools/perf/util/parse-options.c
+++ b/tools/perf/util/parse-options.c
@@ -407,7 +407,9 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
                 if (internal_help && !strcmp(arg + 2, "help"))
                         return usage_with_options_internal(usagestr, options, 0);
                 if (!strcmp(arg + 2, "list-opts"))
-                        return PARSE_OPT_LIST;
+                        return PARSE_OPT_LIST_OPTS;
+                if (!strcmp(arg + 2, "list-cmds"))
+                        return PARSE_OPT_LIST_SUBCMDS;
                 switch (parse_long_opt(ctx, arg + 2, options)) {
                 case -1:
                         return parse_options_usage(usagestr, options, arg + 2, 0);
@@ -433,25 +435,45 @@ int parse_options_end(struct parse_opt_ctx_t *ctx)
         return ctx->cpidx + ctx->argc;
 }
 
-int parse_options(int argc, const char **argv, const struct option *options,
-                  const char * const usagestr[], int flags)
+int parse_options_subcommand(int argc, const char **argv, const struct option *options,
+                        const char *const subcommands[], const char *usagestr[], int flags)
 {
         struct parse_opt_ctx_t ctx;
 
         perf_header__set_cmdline(argc, argv);
 
+        /* build usage string if it's not provided */
+        if (subcommands && !usagestr[0]) {
+                struct strbuf buf = STRBUF_INIT;
+
+                strbuf_addf(&buf, "perf %s [<options>] {", argv[0]);
+                for (int i = 0; subcommands[i]; i++) {
+                        if (i)
+                                strbuf_addstr(&buf, "|");
+                        strbuf_addstr(&buf, subcommands[i]);
+                }
+                strbuf_addstr(&buf, "}");
+
+                usagestr[0] = strdup(buf.buf);
+                strbuf_release(&buf);
+        }
+
         parse_options_start(&ctx, argc, argv, flags);
         switch (parse_options_step(&ctx, options, usagestr)) {
         case PARSE_OPT_HELP:
                 exit(129);
         case PARSE_OPT_DONE:
                 break;
-        case PARSE_OPT_LIST:
+        case PARSE_OPT_LIST_OPTS:
                 while (options->type != OPTION_END) {
                         printf("--%s ", options->long_name);
                         options++;
                 }
                 exit(130);
+        case PARSE_OPT_LIST_SUBCMDS:
+                for (int i = 0; subcommands[i]; i++)
+                        printf("%s ", subcommands[i]);
+                exit(130);
         default: /* PARSE_OPT_UNKNOWN */
                 if (ctx.argv[0][1] == '-') {
                         error("unknown option `%s'", ctx.argv[0] + 2);
@@ -464,6 +486,13 @@ int parse_options(int argc, const char **argv, const struct option *options,
         return parse_options_end(&ctx);
 }
 
+int parse_options(int argc, const char **argv, const struct option *options,
+                  const char * const usagestr[], int flags)
+{
+        return parse_options_subcommand(argc, argv, options, NULL,
+                                        (const char **) usagestr, flags);
+}
+
 #define USAGE_OPTS_WIDTH 24
 #define USAGE_GAP         2
 
diff --git a/tools/perf/util/parse-options.h b/tools/perf/util/parse-options.h
index cbf0149cf221..d8dac8ac5f37 100644
--- a/tools/perf/util/parse-options.h
+++ b/tools/perf/util/parse-options.h
@@ -140,6 +140,11 @@ extern int parse_options(int argc, const char **argv,
                          const struct option *options,
                          const char * const usagestr[], int flags);
 
+extern int parse_options_subcommand(int argc, const char **argv,
+                                const struct option *options,
+                                const char *const subcommands[],
+                                const char *usagestr[], int flags);
+
 extern NORETURN void usage_with_options(const char * const *usagestr,
                                         const struct option *options);
 
@@ -148,7 +153,8 @@ extern NORETURN void usage_with_options(const char * const *usagestr,
 enum {
         PARSE_OPT_HELP = -1,
         PARSE_OPT_DONE,
-        PARSE_OPT_LIST,
+        PARSE_OPT_LIST_OPTS,
+        PARSE_OPT_LIST_SUBCMDS,
         PARSE_OPT_UNKNOWN,
 };