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perf kvm: Check kvm_need_default_arch_event() early

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There's a subtle issue with option parsing in perf record.  It calls the
function with PARSE_OPT_STOP_AT_NON_OPTION so that it can pass later
options to the external command it runs.

But perf kvm record passes the default arch events after the argv.  So
if user calls it with command, then it passes the event to the external
command and fails it like below:

  $ sudo perf kvm --host record sleep 1
  sleep: invalid option -- 'e'
  Try 'sleep --help' for more information.
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.046 MB perf.data.kvm (5 samples) ]

We can check if the default options are needed before passing the extra
command line to make sure it's passed to perf record.

Tested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Namhyung Kim
2026-07-01 12:41:49 -07:00
parent d12a0135e8
commit 95e6323838
1 changed files with 11 additions and 10 deletions
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21
tools/perf/builtin-kvm.c
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@@ -1996,13 +1996,14 @@ static int __cmd_record(const char *file_name, int argc, const char **argv)
{
int rec_argc, i = 0, j, ret;
const char **rec_argv;
int need_arch_event = !!kvm_need_default_arch_event(EM_HOST, argc, argv);
/*
* Besides the 2 more options "-o" and "filename",
* kvm_add_default_arch_event() may add 2 extra options,
* so allocate 4 more items.
* so allocate more items conditionally.
*/
rec_argc = argc + 2 + 2;
rec_argc = argc + 2 + (2 * need_arch_event);
rec_argv = calloc(rec_argc + 1, sizeof(char *));
if (!rec_argv)
return -ENOMEM;
@@ -2010,22 +2011,22 @@ static int __cmd_record(const char *file_name, int argc, const char **argv)
rec_argv[i++] = STRDUP_FAIL_EXIT("record");
rec_argv[i++] = STRDUP_FAIL_EXIT("-o");
rec_argv[i++] = STRDUP_FAIL_EXIT(file_name);
for (j = 1; j < argc; j++, i++)
rec_argv[i] = STRDUP_FAIL_EXIT(argv[j]);
BUG_ON(i + 2 != rec_argc);
if (kvm_need_default_arch_event(EM_HOST, argc, argv)) {
if (need_arch_event) {
ret = kvm_add_default_arch_event(EM_HOST, &i, rec_argv);
if (ret)
goto EXIT;
}
for (j = 1; j < argc; j++, i++)
rec_argv[i] = STRDUP_FAIL_EXIT(argv[j]);
BUG_ON(i != rec_argc);
ret = cmd_record(i, rec_argv);
EXIT:
for (i = 0; i < rec_argc; i++)
free((void *)rec_argv[i]);
for (j = 0; j < i; j++)
free((void *)rec_argv[j]);
free(rec_argv);
return ret;
}