powerpc/perf: Set PPC_FEATURE2_EBB when we register the power8 PMU

The presence or absence of EBB is advertised to userspace via the presence
or absence of PPC_FEATURE2_EBB in cpu_user_features2.

Because the kernel can be built without PMU support, we should only add
PPC_FEATURE2_EBB to cpu_user_features2 when we successfully register the
power8 PMU support.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c
index 96a64d6a8bdf3dfbba1c5a57f16bcb38d3c8a7ce..09def196f5c44a8d5d0a56bf0cdcbf94a2a2914f 100644 (file)
--- a/arch/powerpc/perf/power8-pmu.c
+++ b/arch/powerpc/perf/power8-pmu.c
@@ -621,10 +621,19 @@ static struct power_pmu power8_pmu = {
 
 static int __init init_power8_pmu(void)
 {
+       int rc;
+
        if (!cur_cpu_spec->oprofile_cpu_type ||
            strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power8"))
                return -ENODEV;
 
-       return register_power_pmu(&power8_pmu);
+       rc = register_power_pmu(&power8_pmu);
+       if (rc)
+               return rc;
+
+       /* Tell userspace that EBB is supported */
+       cur_cpu_spec->cpu_user_features2 |= PPC_FEATURE2_EBB;
+
+       return 0;
 }
 early_initcall(init_power8_pmu);