Re: [PATCH 32/35] perf intel-pt: Determine guest thread from guest sideband

Ian Rogers
2022-07-20T01:21:31Z

On Mon, Jul 11, 2022 at 2:34 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> Prior to decoding, determine what guest thread, if any, is running.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
> tools/perf/util/intel-pt.c | 69 ++++++++++++++++++++++++++++++++++++--
> 1 file changed, 67 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index dc2af64f9e31..a08c2f059d5a 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -196,6 +196,10 @@ struct intel_pt_queue {
> struct machine *guest_machine;
> struct thread *guest_thread;
> struct thread *unknown_guest_thread;
> + pid_t guest_machine_pid;
> + pid_t guest_pid;
> + pid_t guest_tid;
> + int vcpu;
> bool exclude_kernel;
> bool have_sample;
> u64 time;
> @@ -759,8 +763,13 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
> cpumode = intel_pt_nr_cpumode(ptq, *ip, nr);
>
> if (nr) {
> - if ((!symbol_conf.guest_code && cpumode != PERF_RECORD_MISC_GUEST_KERNEL) ||
> - intel_pt_get_guest(ptq)) {
> + if (ptq->pt->have_guest_sideband) {
> + if (!ptq->guest_machine || ptq->guest_machine_pid != ptq->pid) {
> + intel_pt_log("ERROR: guest sideband but no guest machine\n");
> + return -EINVAL;
> + }
> + } else if ((!symbol_conf.guest_code && cpumode != PERF_RECORD_MISC_GUEST_KERNEL) ||
> + intel_pt_get_guest(ptq)) {
> intel_pt_log("ERROR: no guest machine\n");
> return -EINVAL;
> }
> @@ -1385,6 +1394,55 @@ static void intel_pt_first_timestamp(struct intel_pt *pt, u64 timestamp)
> }
> }
>
> +static int intel_pt_get_guest_from_sideband(struct intel_pt_queue *ptq)
> +{
> + struct machines *machines = &ptq->pt->session->machines;
> + struct machine *machine;
> + pid_t machine_pid = ptq->pid;
> + pid_t tid;
> + int vcpu;
> +
> + if (machine_pid <= 0)
> + return 0; /* Not a guest machine */
> +
> + machine = machines__find(machines, machine_pid);
> + if (!machine)
> + return 0; /* Not a guest machine */
> +
> + if (ptq->guest_machine != machine) {
> + ptq->guest_machine = NULL;
> + thread__zput(ptq->guest_thread);
> + thread__zput(ptq->unknown_guest_thread);
> +
> + ptq->unknown_guest_thread = machine__find_thread(machine, 0, 0);
> + if (!ptq->unknown_guest_thread)
> + return -1;
> + ptq->guest_machine = machine;
> + }
> +
> + vcpu = ptq->thread ? ptq->thread->guest_cpu : -1;
> + if (vcpu < 0)
> + return -1;
> +
> + tid = machine__get_current_tid(machine, vcpu);
> +
> + if (ptq->guest_thread && ptq->guest_thread->tid != tid)
> + thread__zput(ptq->guest_thread);
> +
> + if (!ptq->guest_thread) {
> + ptq->guest_thread = machine__find_thread(machine, -1, tid);
> + if (!ptq->guest_thread)
> + return -1;
> + }
> +
> + ptq->guest_machine_pid = machine_pid;
> + ptq->guest_pid = ptq->guest_thread->pid_;
> + ptq->guest_tid = tid;
> + ptq->vcpu = vcpu;
> +
> + return 0;
> +}
> +
> static void intel_pt_set_pid_tid_cpu(struct intel_pt *pt,
> struct auxtrace_queue *queue)
> {
> @@ -1405,6 +1463,13 @@ static void intel_pt_set_pid_tid_cpu(struct intel_pt *pt,
> if (queue->cpu == -1)
> ptq->cpu = ptq->thread->cpu;
> }
> +
> + if (pt->have_guest_sideband && intel_pt_get_guest_from_sideband(ptq)) {
> + ptq->guest_machine_pid = 0;
> + ptq->guest_pid = -1;
> + ptq->guest_tid = -1;
> + ptq->vcpu = -1;
> + }
> }
>
> static void intel_pt_sample_flags(struct intel_pt_queue *ptq)
> --
> 2.25.1
>