powerpc/powernv: Re-enable imc trace-mode in kernel
authorAnju T Sudhakar <anju@linux.vnet.ibm.com>
Fri, 13 Mar 2020 05:52:38 +0000 (11:22 +0530)
committerMichael Ellerman <mpe@ellerman.id.au>
Thu, 2 Apr 2020 13:09:58 +0000 (00:09 +1100)
commit <249fad734a25> ""powerpc/perf: Disable trace_imc pmu"
disables IMC(In-Memory Collection) trace-mode in kernel, since frequent
mode switching between accumulation mode and trace mode via the spr LDBAR
in the hardware can trigger a checkstop(system crash).

Patch to re-enable imc-trace mode in kernel.

The previous patch(1/2) in this series will address the mode switching issue
by implementing a global lock, and will restrict the usage of
accumulation and trace-mode at a time.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200313055238.8656-2-anju@linux.vnet.ibm.com
arch/powerpc/platforms/powernv/opal-imc.c

index 968b9a4d1cd9368a8f729dcc214be39a933009fa..7824cc364bc408b2e9af9ffceddb5aa911f79c81 100644 (file)
@@ -268,14 +268,7 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
                        domain = IMC_DOMAIN_THREAD;
                        break;
                case IMC_TYPE_TRACE:
-                       /*
-                        * FIXME. Using trace_imc events to monitor application
-                        * or KVM thread performance can cause a checkstop
-                        * (system crash).
-                        * Disable it for now.
-                        */
-                       pr_info_once("IMC: disabling trace_imc PMU\n");
-                       domain = -1;
+                       domain = IMC_DOMAIN_TRACE;
                        break;
                default:
                        pr_warn("IMC Unknown Device type \n");