linux-kernel - Re: [PATCH v7 2/5] powerpc/hv-24x7: Add rtas call in hv-24x7 driver to get processor details

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Message-ID: <fc2f519f-7dc9-cc72-496e-bc1403aa2178@linux.ibm.com>
Date:   Wed, 29 Apr 2020 13:32:04 +0530
From:   Madhavan Srinivasan <maddy@...ux.ibm.com>
To:     Kajol Jain <kjain@...ux.ibm.com>, acme@...nel.org,
        linuxppc-dev@...ts.ozlabs.org, mpe@...erman.id.au,
        sukadev@...ux.vnet.ibm.com
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        anju@...ux.vnet.ibm.com, maddy@...ux.vnet.ibm.com,
        ravi.bangoria@...ux.ibm.com, peterz@...radead.org,
        yao.jin@...ux.intel.com, ak@...ux.intel.com, jolsa@...nel.org,
        kan.liang@...ux.intel.com, jmario@...hat.com,
        alexander.shishkin@...ux.intel.com, mingo@...nel.org,
        paulus@...abs.org, namhyung@...nel.org, mpetlan@...hat.com,
        gregkh@...uxfoundation.org, benh@...nel.crashing.org,
        mamatha4@...ux.vnet.ibm.com, mark.rutland@....com,
        tglx@...utronix.de
Subject: Re: [PATCH v7 2/5] powerpc/hv-24x7: Add rtas call in hv-24x7 driver
 to get processor details



On 3/27/20 12:06 PM, Kajol Jain wrote:
> For hv_24x7 socket/chip level events, specific chip-id to which
> the data requested should be added as part of pmu events.
> But number of chips/socket in the system details are not exposed.
>
> Patch implements read_sys_info_pseries() to get system
> parameter values like number of sockets and chips per socket.
> Rtas_call with token "PROCESSOR_MODULE_INFO"
> is used to get these values.

Patch looks good to me.

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

> Sub-sequent patch exports these values via sysfs.
>
> Patch also make these parameters default to 1.
>
> Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
> ---
>   arch/powerpc/perf/hv-24x7.c              | 72 ++++++++++++++++++++++++
>   arch/powerpc/platforms/pseries/pseries.h |  3 +
>   2 files changed, 75 insertions(+)
>
> diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
> index 48e8f4b17b91..9ae00f29bd21 100644
> --- a/arch/powerpc/perf/hv-24x7.c
> +++ b/arch/powerpc/perf/hv-24x7.c
> @@ -20,6 +20,11 @@
>   #include <asm/io.h>
>   #include <linux/byteorder/generic.h>
>
> +#ifdef CONFIG_PPC_RTAS
> +#include <asm/rtas.h>
> +#include <../../platforms/pseries/pseries.h>
> +#endif
> +
>   #include "hv-24x7.h"
>   #include "hv-24x7-catalog.h"
>   #include "hv-common.h"
> @@ -57,6 +62,69 @@ static bool is_physical_domain(unsigned domain)
>   	}
>   }
>
> +#ifdef CONFIG_PPC_RTAS
> +#define PROCESSOR_MODULE_INFO   43
> +#define PROCESSOR_MAX_LENGTH	(8 * 1024)
> +
> +static int strbe16toh(const char *buf, int offset)
> +{
> +	return (buf[offset] << 8) + buf[offset + 1];
> +}
> +
> +static u32		physsockets;	/* Physical sockets */
> +static u32		physchips;	/* Physical chips */
> +
> +/*
> + * Function read_sys_info_pseries() make a rtas_call which require
> + * data buffer of size 8K. As standard 'rtas_data_buf' is of size
> + * 4K, we are adding new local buffer 'rtas_local_data_buf'.
> + */
> +char rtas_local_data_buf[PROCESSOR_MAX_LENGTH] __cacheline_aligned;
> +
> +/*
> + * read_sys_info_pseries()
> + * Retrieve the number of sockets and chips per socket details
> + * through the get-system-parameter rtas call.
> + */
> +void read_sys_info_pseries(void)
> +{
> +	int call_status, len, ntypes;
> +
> +	/*
> +	 * Making system parameter: chips and sockets default to 1.
> +	 */
> +	physsockets = 1;
> +	physchips = 1;
> +	memset(rtas_local_data_buf, 0, PROCESSOR_MAX_LENGTH);
> +	spin_lock(&rtas_data_buf_lock);
> +
> +	call_status = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
> +				NULL,
> +				PROCESSOR_MODULE_INFO,
> +				__pa(rtas_local_data_buf),
> +				PROCESSOR_MAX_LENGTH);
> +
> +	spin_unlock(&rtas_data_buf_lock);
> +
> +	if (call_status != 0) {
> +		pr_info("%s %s Error calling get-system-parameter (0x%x)\n",
> +			__FILE__, __func__, call_status);
> +	} else {
> +		rtas_local_data_buf[PROCESSOR_MAX_LENGTH - 1] = '\0';
> +		len = strbe16toh(rtas_local_data_buf, 0);
> +		if (len < 6)
> +			return;
> +
> +		ntypes = strbe16toh(rtas_local_data_buf, 2);
> +
> +		if (!ntypes)
> +			return;
> +		physsockets = strbe16toh(rtas_local_data_buf, 4);
> +		physchips = strbe16toh(rtas_local_data_buf, 6);
> +	}
> +}
> +#endif /* CONFIG_PPC_RTAS */
> +
>   /* Domains for which more than one result element are returned for each event. */
>   static bool domain_needs_aggregation(unsigned int domain)
>   {
> @@ -1605,6 +1673,10 @@ static int hv_24x7_init(void)
>   	if (r)
>   		return r;
>
> +#ifdef CONFIG_PPC_RTAS
> +	read_sys_info_pseries();
> +#endif
> +
>   	return 0;
>   }
>
> diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
> index 13fa370a87e4..1727559ce304 100644
> --- a/arch/powerpc/platforms/pseries/pseries.h
> +++ b/arch/powerpc/platforms/pseries/pseries.h
> @@ -19,6 +19,9 @@ extern void request_event_sources_irqs(struct device_node *np,
>   struct pt_regs;
>
>   extern int pSeries_system_reset_exception(struct pt_regs *regs);
> +#ifdef CONFIG_PPC_RTAS
> +extern void read_sys_info_pseries(void);
> +#endif
>   extern int pSeries_machine_check_exception(struct pt_regs *regs);
>   extern long pseries_machine_check_realmode(struct pt_regs *regs);
>