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Subject: Re: [PATCH v2 4/5] powerpc/perf: Trace imc events detection and
 cpuhotplug
To:     Anju T Sudhakar <anju@linux.vnet.ibm.com>, mpe@ellerman.id.au,
        linux-kernel@vger.kernel.org
Cc:     linuxppc-dev@lists.ozlabs.org
References: <20181214091122.20992-1-anju@linux.vnet.ibm.com>
 <20181214091122.20992-5-anju@linux.vnet.ibm.com>
From:   Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Date:   Wed, 19 Dec 2018 11:38:34 +0530
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On 14/12/18 2:41 PM, Anju T Sudhakar wrote:
> Patch detects trace-imc events, does memory initilizations for each online
> cpu, and registers cpuhotplug call-backs.

Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>

> Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
> ---
>   arch/powerpc/perf/imc-pmu.c               | 91 +++++++++++++++++++++++
>   arch/powerpc/platforms/powernv/opal-imc.c |  3 +
>   include/linux/cpuhotplug.h                |  1 +
>   3 files changed, 95 insertions(+)
>
> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
> index 5ca80545a849..1f09265c8fb0 100644
> --- a/arch/powerpc/perf/imc-pmu.c
> +++ b/arch/powerpc/perf/imc-pmu.c
> @@ -43,6 +43,10 @@ static DEFINE_PER_CPU(u64 *, thread_imc_mem);
>   static struct imc_pmu *thread_imc_pmu;
>   static int thread_imc_mem_size;
>
> +/* Trace IMC data structures */
> +static DEFINE_PER_CPU(u64 *, trace_imc_mem);
> +static int trace_imc_mem_size;
> +
>   static struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
>   {
>   	return container_of(event->pmu, struct imc_pmu, pmu);
> @@ -1068,6 +1072,54 @@ static void thread_imc_event_del(struct perf_event *event, int flags)
>   	imc_event_update(event);
>   }
>
> +/*
> + * Allocate a page of memory for each cpu, and load LDBAR with 0.
> + */
> +static int trace_imc_mem_alloc(int cpu_id, int size)
> +{
> +	u64 *local_mem = per_cpu(trace_imc_mem, cpu_id);
> +	int phys_id = cpu_to_node(cpu_id), rc = 0;
> +
> +	if (!local_mem) {
> +		local_mem = page_address(alloc_pages_node(phys_id,
> +					GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
> +					__GFP_NOWARN, get_order(size)));
> +		if (!local_mem)
> +			return -ENOMEM;
> +		per_cpu(trace_imc_mem, cpu_id) = local_mem;
> +
> +		/* Initialise the counters for trace mode */
> +		rc = opal_imc_counters_init(OPAL_IMC_COUNTERS_TRACE, __pa((void *)local_mem),
> +					    get_hard_smp_processor_id(cpu_id));
> +		if (rc) {
> +			pr_info("IMC:opal init failed for trace imc\n");
> +			return rc;
> +		}
> +	}
> +
> +	mtspr(SPRN_LDBAR, 0);
> +	return 0;
> +}
> +
> +static int ppc_trace_imc_cpu_online(unsigned int cpu)
> +{
> +	return trace_imc_mem_alloc(cpu, trace_imc_mem_size);
> +}
> +
> +static int ppc_trace_imc_cpu_offline(unsigned int cpu)
> +{
> +	mtspr(SPRN_LDBAR, 0);
> +	return 0;
> +}
> +
> +static int trace_imc_cpu_init(void)
> +{
> +	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
> +			  "perf/powerpc/imc_trace:online",
> +			  ppc_trace_imc_cpu_online,
> +			  ppc_trace_imc_cpu_offline);
> +}
> +
>   /* update_pmu_ops : Populate the appropriate operations for "pmu" */
>   static int update_pmu_ops(struct imc_pmu *pmu)
>   {
> @@ -1189,6 +1241,17 @@ static void cleanup_all_thread_imc_memory(void)
>   	}
>   }
>
> +static void cleanup_all_trace_imc_memory(void)
> +{
> +	int i, order = get_order(trace_imc_mem_size);
> +
> +	for_each_online_cpu(i) {
> +		if (per_cpu(trace_imc_mem, i))
> +			free_pages((u64)per_cpu(trace_imc_mem, i), order);
> +
> +	}
> +}
> +
>   /* Function to free the attr_groups which are dynamically allocated */
>   static void imc_common_mem_free(struct imc_pmu *pmu_ptr)
>   {
> @@ -1230,6 +1293,11 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
>   		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE);
>   		cleanup_all_thread_imc_memory();
>   	}
> +
> +	if (pmu_ptr->domain == IMC_DOMAIN_TRACE) {
> +		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE);
> +		cleanup_all_trace_imc_memory();
> +	}
>   }
>
>   /*
> @@ -1312,6 +1380,21 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, struct device_node *parent,
>
>   		thread_imc_pmu = pmu_ptr;
>   		break;
> +	case IMC_DOMAIN_TRACE:
> +		/* Update the pmu name */
> +		pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s", s, "_imc");
> +		if (!pmu_ptr->pmu.name)
> +			return -ENOMEM;
> +
> +		trace_imc_mem_size = pmu_ptr->counter_mem_size;
> +		for_each_online_cpu(cpu) {
> +			res = trace_imc_mem_alloc(cpu, trace_imc_mem_size);
> +			if (res) {
> +				cleanup_all_trace_imc_memory();
> +				goto err;
> +			}
> +		}
> +		break;
>   	default:
>   		return -EINVAL;
>   	}
> @@ -1384,6 +1467,14 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id
>   			goto err_free_mem;
>   		}
>
> +		break;
> +	case IMC_DOMAIN_TRACE:
> +		ret = trace_imc_cpu_init();
> +		if (ret) {
> +			cleanup_all_trace_imc_memory();
> +			goto err_free_mem;
> +		}
> +
>   		break;
>   	default:
>   		return  -EINVAL;	/* Unknown domain */
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
> index 58a07948c76e..dedc9ae22662 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -284,6 +284,9 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
>   		case IMC_TYPE_THREAD:
>   			domain = IMC_DOMAIN_THREAD;
>   			break;
> +		case IMC_TYPE_TRACE:
> +			domain = IMC_DOMAIN_TRACE;
> +			break;
>   		default:
>   			pr_warn("IMC Unknown Device type \n");
>   			domain = -1;
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index e0cd2baa8380..c471f2de878b 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -167,6 +167,7 @@ enum cpuhp_state {
>   	CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
>   	CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
>   	CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
> +	CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
>   	CPUHP_AP_WATCHDOG_ONLINE,
>   	CPUHP_AP_WORKQUEUE_ONLINE,
>   	CPUHP_AP_RCUTREE_ONLINE,