linux-kernel - [PATCH v5 28/29] x86/resctrl: Add info/PERF_PKG

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Message-ID: <20250521225049.132551-29-tony.luck@intel.com>
Date: Wed, 21 May 2025 15:50:46 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.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,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v5 28/29] x86/resctrl: Add info/PERF_PKG_MON/status file

Each telemetry aggregator provides three status registers at the top
end of MMIO space after all the per-RMID per-event counters:

  agg_data_loss_count: This counts the number of times that this aggregator
  failed to accumulate a counter value supplied by a CPU core.

  agg_data_loss_timestamp: This is a "timestamp" from a free running
  25MHz uncore timer indicating when the most recent data loss occurred.

  last_update_timestamp: Another 25MHz timestamp indicating when the
  most recent counter update was successfully applied.

When the resctrl file system is mounted with the "-o debug" option
display the values of each of these status registers for each aggregator
in each enabled event group.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 34 +++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 1b41167ad976..459e42459178 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -16,6 +16,7 @@
 #include <linux/io.h>
 #include <linux/minmax.h>
 #include <linux/resctrl.h>
+#include <linux/seq_file.h>
 #include <linux/slab.h>
 
 /* Temporary - delete from final version */
@@ -282,6 +283,35 @@ static bool get_pmt_feature(enum pmt_feature_id feature)
 	return false;
 }
 
+static void show_debug(struct seq_file *s, struct event_group *e, int pkg, int instance)
+{
+	void __iomem *info = e->pkginfo[pkg]->addrs[instance] + e->mmio_size;
+
+	/* Information registers are the last three qwords in MMIO space */
+	seq_printf(s, "%s %d:%d agg_data_loss_count = %llu\n", e->name, pkg, instance,
+		   readq(info - 24));
+	seq_printf(s, "%s %d:%d agg_data_loss_timestamp = %llu\n", e->name, pkg, instance,
+		   readq(info - 16));
+	seq_printf(s, "%s %d:%d last_update_timestamp = %llu\n", e->name, pkg, instance,
+		   readq(info - 8));
+}
+
+static int info_status(struct kernfs_open_file *of, struct seq_file *s, void *v)
+{
+	int num_pkgs = topology_max_packages();
+	struct event_group **eg;
+
+	for (eg = &known_event_groups[0]; eg < &known_event_groups[NUM_KNOWN_GROUPS]; eg++) {
+		if (!(*eg)->pfg)
+			continue;
+		for (int i = 0; i < num_pkgs; i++)
+			for (int j = 0; j < (*eg)->pkginfo[i]->count; j++)
+				show_debug(s, *eg, i, j);
+	}
+
+	return 0;
+}
+
 /*
  * Ask OOBMSM discovery driver for all the RMID based telemetry groups
  * that it supports.
@@ -304,6 +334,10 @@ bool intel_aet_get_events(void)
 			r->num_rmid = (*eg)->num_rmids;
 	}
 
+	r->info_file.name = "status";
+	r->info_file.seq_show = info_status;
+	r->info_file.flags = RFTYPE_DEBUG;
+
 	return ret1 || ret2;
 }
 
-- 
2.49.0