[PATCH 20/31] x86/resctrl: Find and enable usable telemetry events

[Tony Luck]

The INTEL_PMT driver provides telemetry region structures of the
types requested by resctrl.

Scan these structures to discover which pass sanity checks:

1) They have guid known to resctrl.
2) They have a valid package ID.
3) The enumerated size of the MMIO region matches the expected
   value from the XML description file.
4) At least one region passes the above checks.

Enable the active events in resctrl filesystem to make them available to
user space. Pass a pointer to the pmt_event structure of the event within
the struct event_group that resctrl stores in mon_evt::arch_priv. resctrl
passes this pointer back when asking to read the event data which enables
the data to be found in MMIO.

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
 arch/x86/kernel/cpu/resctrl/intel_aet.c | 38 +++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 93862060652a..e36b3790733b 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -20,9 +20,11 @@
 #include <linux/intel_pmt_features.h>
 #include <linux/intel_vsec.h>
 #include <linux/overflow.h>
+#include <linux/printk.h>
 #include <linux/resctrl.h>
 #include <linux/resctrl_types.h>
 #include <linux/stddef.h>
+#include <linux/topology.h>
 #include <linux/types.h>
 
 #include "internal.h"
@@ -111,12 +113,44 @@ static struct event_group *known_perf_event_groups[] = {
 	for (_peg = (_grp); _peg < &_grp[ARRAY_SIZE(_grp)]; _peg++)	\
 		if ((*_peg)->pfg)
 
-/* Stub for now */
-static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
+static bool skip_telem_region(struct telemetry_region *tr, struct event_group *e)
 {
+	if (tr->guid != e->guid)
+		return true;
+	if (tr->plat_info.package_id >= topology_max_packages()) {
+		pr_warn("Bad package %d in guid 0x%x\n", tr->plat_info.package_id,
+			tr->guid);
+		return true;
+	}
+	if (tr->size != e->mmio_size) {
+		pr_warn("MMIO space wrong size (%zu bytes) for guid 0x%x. Expected %zu bytes.\n",
+			tr->size, e->guid, e->mmio_size);
+		return true;
+	}
+
 	return false;
 }
 
+static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
+{
+	bool usable_events = false;
+
+	for (int i = 0; i < p->count; i++) {
+		if (skip_telem_region(&p->regions[i], e))
+			continue;
+		usable_events = true;
+	}
+
+	if (!usable_events)
+		return false;
+
+	for (int j = 0; j < e->num_events; j++)
+		resctrl_enable_mon_event(e->evts[j].id, true,
+					 e->evts[j].bin_bits, &e->evts[j]);
+
+	return true;
+}
+
 DEFINE_FREE(intel_pmt_put_feature_group, struct pmt_feature_group *,
 		if (!IS_ERR_OR_NULL(_T))
 			intel_pmt_put_feature_group(_T))
-- 
2.51.0