linux-kernel - Re: [PATCH v6 22/30] x86/resctrl: Read core telemetry events

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Message-ID: <37708e34-9634-4488-aeb7-6a61ab01947a@intel.com>
Date: Wed, 9 Jul 2025 08:48:47 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.com>, "Maciej
 Wieczor-Retman" <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>, Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v6 22/30] x86/resctrl: Read core telemetry events

Hi Tony,

What does the "core" in the subject refer to?

On 6/26/25 9:49 AM, Tony Luck wrote:
> The resctrl file system passes requests to read event monitor files to
> the architecture resctrl_arch_rmid_read() to collect values
> from hardware counters.
> 
> Use the resctrl resource to differentiate between calls to read legacy
> L3 events from the new telemetry events (which are attached to
> RDT_RESOURCE_PERF_PKG).
> 
> There may be multiple aggregators tracking each package, so scan all of
> them and add up all counters.
> 
> Enable the events marked as readable from any CPU providing an
> mon_evt::arch_priv pointer to the struct pmt_event for each
> event.
> 
> At run time when a user reads an event file the file system code
> provides the enum resctrl_event_id for the event and the arch_priv
> pointer that was supplied when the event was enabled.
> 
> Resctrl now uses readq() so depends on X86_64. Update Kconfig.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  arch/x86/kernel/cpu/resctrl/internal.h  |  2 ++
>  arch/x86/kernel/cpu/resctrl/intel_aet.c | 46 +++++++++++++++++++++++++
>  arch/x86/kernel/cpu/resctrl/monitor.c   |  3 ++
>  arch/x86/Kconfig                        |  2 +-
>  4 files changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index e93b15bf6aab..e8d2a754bc0c 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -171,5 +171,7 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
>  
>  bool intel_aet_get_events(void);
>  void __exit intel_aet_exit(void);
> +int intel_aet_read_event(int domid, int rmid, enum resctrl_event_id evtid,
> +			 void *arch_priv, u64 *val);
>  
>  #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index f9b2959693a0..10fd8b04105e 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -14,6 +14,7 @@
>  #include <linux/cleanup.h>
>  #include <linux/cpu.h>
>  #include <linux/intel_vsec.h>
> +#include <linux/io.h>
>  #include <linux/resctrl.h>
>  #include <linux/slab.h>
>  
> @@ -206,6 +207,13 @@ static int configure_events(struct event_group *e, struct pmt_feature_group *p)
>  	}
>  	e->pkginfo = no_free_ptr(pkginfo);
>  
> +	for (int i = 0; i < e->num_events; i++) {
> +		enum resctrl_event_id eventid;
> +
> +		eventid = e->evts[i].id;
> +		resctrl_enable_mon_event(eventid, true, e->evts[i].bin_bits, &e->evts[i]);
> +	}
> +
>  	return 0;
>  }
>  
> @@ -268,3 +276,41 @@ void __exit intel_aet_exit(void)
>  		free_mmio_info((*peg)->pkginfo);
>  	}
>  }
> +
> +#define DATA_VALID	BIT_ULL(63)
> +#define DATA_BITS	GENMASK_ULL(62, 0)
> +
> +/*
> + * Read counter for an event on a domain (summing all aggregators
> + * on the domain).
> + */
> +int intel_aet_read_event(int domid, int rmid, enum resctrl_event_id eventid,
> +			 void *arch_priv, u64 *val)
> +{
> +	struct pmt_event *pevt = arch_priv;
> +	struct mmio_info *mmi;
> +	struct event_group *e;
> +	u64 evtcount;
> +	void *pevt0;

Should this be a struct pmt_event *?

> +	int idx;
> +
> +	pevt0 = pevt - pevt->idx;
> +	e = container_of(pevt0, struct event_group, evts);
> +	idx = rmid * e->num_events;
> +	idx += pevt->idx;
> +	mmi = e->pkginfo[domid];
> +
> +	if (idx * sizeof(u64) + sizeof(u64) > e->mmio_size) {
> +		pr_warn_once("MMIO index %d out of range\n", idx);
> +		return -EIO;
> +	}
> +
> +	for (int i = 0; i < mmi->num_regions; i++) {
> +		evtcount = readq(mmi->addrs[i] + idx * sizeof(u64));
> +		if (!(evtcount & DATA_VALID))
> +			return -EINVAL;
> +		*val += evtcount & DATA_BITS;
> +	}
> +
> +	return 0;
> +}
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 185b203f6321..51d7d99336c6 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -232,6 +232,9 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
>  
>  	resctrl_arch_rmid_read_context_check();
>  
> +	if (r->rid == RDT_RESOURCE_PERF_PKG)
> +		return intel_aet_read_event(hdr->id, rmid, eventid, arch_priv, val);
> +
>  	if (r->rid != RDT_RESOURCE_L3)
>  		return -EINVAL;
>  

This part looks good to me. I expect Kconfig part to look different next time.

Reinette