[PATCH] powerpc/perf: Fix the guest crash issue with trace-imc

[Athira Rajeev]

when perf kvm record with trace_imc event is attach to guest
pid(with -p option), the qemu process gets killed with permission
issue. This happens because trace_imc event requires admin privileges
to monitor the process.If the qemu creates threads, by default
child tasks also inherit the counters and if there is no permission
to monitor qemu threads, we return permission denied ( EACCES ).

Fix this by returning EACCES only if there is no CAP_SYS_ADMIN and the
event doesn’t have inheritance.

Fixes: 012ae244845f ("powerpc/perf: Trace imc PMU functions")
Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
---
 arch/powerpc/perf/imc-pmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index e106909ff9c3..cc5679bfd28b 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1429,7 +1429,7 @@ static int trace_imc_event_init(struct perf_event *event)
 	if (event->attr.type != event->pmu->type)
 		return -ENOENT;
 
-	if (!perfmon_capable())
+	if (!perfmon_capable() && !event->attr.inherit)
 		return -EACCES;
 
 	/* Return if this is a couting event */
-- 
1.8.3.1