[PATCH v2 1/2] lib: sbi_pmu: do not ignore pmu_ctr_start_hw() error in cfg_match

[Sebastian Alba Vives]

sbi_pmu_ctr_cfg_match() calls pmu_ctr_start_hw() for the AUTO_START
flag and drops the result. pmu_ctr_start_hw() carries its own index
guard

	if (cidx >= num_hw_ctrs || cidx == 1)
		return SBI_EINVAL;

and can also return SBI_EALREADY_STARTED when the counter is already
running. Both are reported to the caller as a successful configure.

Neither is benign. A rejected index means nothing was configured, and
an already running counter may have been configured for a different
event previously, so the supervisor must not be told its configure
succeeded.

This is also the only one of the three start paths in the file that
discards the error. sbi_pmu_ctr_start() propagates it:

	ret = pmu_ctr_start_hw(cidx, ival, bUpdate);
	if (ret)
		return ret;

and the firmware branch directly below this call site propagates the
error from pmu_dev->fw_counter_start() as well.

Fixes: 13d40f21d588 ("lib: sbi: Add PMU support")
Signed-off-by: Sebastian Alba Vives <sebasjosue84 at gmail.com>
---
 lib/sbi/sbi_pmu.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
index bf43ad89..c68a675a 100644
--- a/lib/sbi/sbi_pmu.c
+++ b/lib/sbi/sbi_pmu.c
@@ -982,8 +982,11 @@ skip_match:
 	    event_type == SBI_PMU_EVENT_TYPE_HW_RAW_V2) {
 		if (flags & SBI_PMU_CFG_FLAG_CLEAR_VALUE)
 			pmu_ctr_write_hw(ctr_idx, 0);
-		if (flags & SBI_PMU_CFG_FLAG_AUTO_START)
-			pmu_ctr_start_hw(ctr_idx, 0, false);
+		if (flags & SBI_PMU_CFG_FLAG_AUTO_START) {
+			ret = pmu_ctr_start_hw(ctr_idx, 0, false);
+			if (ret)
+				return ret;
+		}
 	} else if (event_type == SBI_PMU_EVENT_TYPE_FW) {
 		if (flags & SBI_PMU_CFG_FLAG_CLEAR_VALUE)
 			phs->fw_counters_data[ctr_idx - num_hw_ctrs] = 0;
-- 
2.43.0