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SubjectRe: [PATCH v7 2/5] powerpc/hv-24x7: Add rtas call in hv-24x7 driver to get processor details
Date
Hi Kajol,

Some comments inline ...

Kajol Jain <kjain@linux.ibm.com> writes:
> 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.
>
> Sub-sequent patch exports these values via sysfs.
>
> Patch also make these parameters default to 1.
>
> Signed-off-by: Kajol Jain <kjain@linux.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

This driver can only be build on pseries, and pseries always selects
RTAS. So the ifdef is unncessary.

> +#include <asm/rtas.h>
> +#include <../../platforms/pseries/pseries.h>
> +#endif

That's not really what the platform header is intended for.

You should put the extern in arch/powerpc/include/asm somewhere.

Maybe rtas.h

> @@ -57,6 +62,69 @@ static bool is_physical_domain(unsigned domain)
> }
> }
>
> +#ifdef CONFIG_PPC_RTAS

Not needed.

> +#define PROCESSOR_MODULE_INFO 43

Please document where these come from, presumably LoPAPR somewhere?

> +#define PROCESSOR_MAX_LENGTH (8 * 1024)
> +
> +static int strbe16toh(const char *buf, int offset)
> +{
> + return (buf[offset] << 8) + buf[offset + 1];
> +}

I'm confused by this. "str" implies string, a string is an array of
bytes and has no endian. But then be16 implies it's an array of __be16,
in which case buf should be a __be16 *.

> +
> +static u32 physsockets; /* Physical sockets */
> +static u32 physchips; /* Physical chips */

No tabs there please.

> +
> +/*
> + * 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;

static?

> +/*
> + * 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);

You're not using the rtas_data_buf, so why are you taking the
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);

pr_err(), don't use __FILE__, this file already uses pr_fmt(). Not sure
__func__ is really necessary either.

return;

Then you can deindent the next block.

> + } else {
> + rtas_local_data_buf[PROCESSOR_MAX_LENGTH - 1] = '\0';
> + len = strbe16toh(rtas_local_data_buf, 0);

Why isn't the buffer a __be16 array, and then you just use be16_to_cpu() ?

> + if (len < 6)
> + return;
> +
> + ntypes = strbe16toh(rtas_local_data_buf, 2);
> +
> + if (!ntypes)
> + return;

What is ntypes?

> + 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);


cheers

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