[PATCH] powerpc/perf: Disable trace_imc pmu

[Oliver O'Halloran]

On Thu, Nov 14, 2019 at 6:19 PM Madhavan Srinivasan
<maddy at linux.vnet.ibm.com> wrote:
>
> When a root user or a user with CAP_SYS_ADMIN
> privilege use trace_imc performance monitoring
> unit events, to monitor application or KVM threads,
> may result in a checkstop (System crash). Reason
> being frequent switch of the "trace/accumulation"
> mode of In-Memory Collection hardware.
> This patch disables trace_imc pmu unit, but will
> be re-enabled at a later stage with a fix patchset.
> ---
>  arch/powerpc/platforms/powernv/opal-imc.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
> index e04b20625cb9..5790f078771f 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -285,7 +285,12 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
>                         domain = IMC_DOMAIN_THREAD;
>                         break;
>                 case IMC_TYPE_TRACE:
> -                       domain = IMC_DOMAIN_TRACE;
> +                       /* Using trace_imc events to monitor
> +                        * application or KVM thread performances
> +                        * may result in a checkstop (system crash).
> +                        * So disabling it for now.
> +                        */
> +                       domain = -1;
>                         break;
>                 default:
>                         pr_warn("IMC Unknown Device type \n");
> --
> 2.21.0
>

Does this need a Fixes: tag?