perf kvm: Fix subcommand matching error

Currently the 'diff', 'top', 'buildid-list' and 'stat' perf commands use
strncmp() to match subcommands.  As a result, matching does not meet
expectation.

For example:
  # perf kvm diff1234
  # Event 'cycles'
  #
  # Baseline  Delta Abs  Shared Object  Symbol
  # ........  .........  .............  ......
  #

  # Event 'dummy:HG'
  #
  # Baseline  Delta Abs  Shared Object  Symbol
  # ........  .........  .............  ......
  #
  # echo $?
  0
  #

Invalid information should be returned, but success is actually returned.

Solution: Use strstarts() to match subcommands.

After:
  # perf kvm diff1234

   Usage: perf kvm [<options>] {top|record|report|diff|buildid-list|stat}

      -i, --input <file>    Input file name
      -o, --output <file>   Output file name
      -v, --verbose         be more verbose (show counter open errors, etc)
          --guest           Collect guest os data
          --guest-code      Guest code can be found in hypervisor process
          --guestkallsyms <file>
                            file saving guest os /proc/kallsyms
          --guestmodules <file>
                            file saving guest os /proc/modules
          --guestmount <directory>
                            guest mount directory under which every guest os instance has a subdir
          --guestvmlinux <file>
                            file saving guest os vmlinux
          --host            Collect host os data

  # echo $?
  129
  #

Signed-off-by: Yang Jihong <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions