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Message-ID: <20250521225049.132551-26-tony.luck@intel.com>
Date: Wed, 21 May 2025 15:50:43 -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 25/29] x86/resctrl: Handle number of RMIDs supported by telemetry resources
There are now three meanings for "number of RMIDs":
1) The number for legacy features enumerated by CPUID leaf 0xF. This
is the maximum number of distinct values that can be loaded into the
IA32_PQR_ASSOC MSR. Note that systems with Sub-NUMA Cluster mode enabled
will force scaling down the CPUID enumerated value by the number of SNC
nodes per L3-cache.
2) The number of registers in MMIO space for each event. This
is enumerated in the XML files and is the value initialized into
event_group::num_rmids. This will be overwritten with a lower
value if hardware does not support all these registers at the
same time (see next case).
3) The number of "h/w counters" (this isn't a strictly accurate
description of how things work, but serves as a useful analogy that
does describe the limitations) feeding to those MMIO registers. This
is enumerated in telemetry_region::num_rmids returned from the call to
intel_pmt_get_regions_by_feature()
Event groups with insufficient "h/w counter" to track all RMIDs are
difficult for users to use, since the system may reassign "h/w counters"
as any time. This means that users cannot reliably collect two consecutive
event counts to compute the rate at which events are occurring.
Ignore such under-resourced event groups unless the user explicitly
requests to enable them using the "rdt=" Linux boot argument.
Scan all enabled event groups and assign the RDT_RESOURCE_PERF_PKG
resource "num_rmids" value to the smallest of these values to ensure
that all resctrl groups have equal monitor capabilities.
N.B. Changed type of rdt_resource::num_rmids to u32 to match.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
include/linux/resctrl.h | 2 +-
arch/x86/kernel/cpu/resctrl/internal.h | 2 ++
arch/x86/kernel/cpu/resctrl/intel_aet.c | 27 +++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/monitor.c | 2 ++
4 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 4ba51cb598e1..b7e15abcde23 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -286,7 +286,7 @@ struct rdt_resource {
int rid;
bool alloc_capable;
bool mon_capable;
- int num_rmid;
+ u32 num_rmid;
enum resctrl_scope ctrl_scope;
enum resctrl_scope mon_scope;
struct resctrl_cache cache;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 524f3c183900..795534b9b9d2 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -18,6 +18,8 @@
#define RMID_VAL_UNAVAIL BIT_ULL(62)
+extern int rdt_num_system_rmids;
+
/*
* With the above fields in use 62 bits remain in MSR_IA32_QM_CTR for
* data to be returned. The counter width is discovered from the hardware
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index c1fc85dbf0d8..1b41167ad976 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/io.h>
+#include <linux/minmax.h>
#include <linux/resctrl.h>
#include <linux/slab.h>
@@ -57,6 +58,9 @@ struct pmt_event {
* telemetry regions.
* @pkginfo: Per-package MMIO addresses of telemetry regions belonging to this group
* @guid: Unique number per XML description file.
+ * @num_rmids: Number of RMIDS supported by this group. Will be adjusted downwards
+ * if enumeration from intel_pmt_get_regions_by_feature() indicates
+ * fewer RMIDs can be tracked simultaneously.
* @mmio_size: Number of bytes of MMIO registers for this group.
* @num_events: Number of events in this group.
* @evts: Array of event descriptors.
@@ -69,6 +73,7 @@ struct event_group {
/* Remaining fields initialized from XML file. */
u32 guid;
+ u32 num_rmids;
size_t mmio_size;
int num_events;
struct pmt_event evts[] __counted_by(num_events);
@@ -81,6 +86,7 @@ struct event_group {
static struct event_group energy_0x26696143 = {
.name = "energy",
.guid = 0x26696143,
+ .num_rmids = 576,
.mmio_size = (576 * 2 + 3) * 8,
.num_events = 2,
.evts = {
@@ -96,6 +102,7 @@ static struct event_group energy_0x26696143 = {
static struct event_group perf_0x26557651 = {
.name = "perf",
.guid = 0x26557651,
+ .num_rmids = 576,
.mmio_size = (576 * 7 + 3) * 8,
.num_events = 7,
.evts = {
@@ -253,6 +260,15 @@ static bool get_pmt_feature(enum pmt_feature_id feature)
if ((*peg)->guid == p->regions[i].guid) {
if (rdt_is_option_force_disabled((*peg)->name))
return false;
+ /*
+ * Ignore event group with insufficient RMIDs unless the
+ * user used the rdt= boot option to specifically ask
+ * for it to be enabled.
+ */
+ if (p->regions[i].num_rmids < rdt_num_system_rmids &&
+ !rdt_is_option_force_enabled((*peg)->name))
+ return false;
+ (*peg)->num_rmids = min((*peg)->num_rmids, p->regions[i].num_rmids);
ret = configure_events(*peg, p);
if (!ret) {
(*peg)->pfg = no_free_ptr(p);
@@ -272,11 +288,22 @@ static bool get_pmt_feature(enum pmt_feature_id feature)
*/
bool intel_aet_get_events(void)
{
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
+ struct event_group **eg;
bool ret1, ret2;
ret1 = get_pmt_feature(FEATURE_PER_RMID_ENERGY_TELEM);
ret2 = get_pmt_feature(FEATURE_PER_RMID_PERF_TELEM);
+ for (eg = &known_event_groups[0]; eg < &known_event_groups[NUM_KNOWN_GROUPS]; eg++) {
+ if (!(*eg)->pfg)
+ continue;
+ if (r->num_rmid)
+ r->num_rmid = min(r->num_rmid, (*eg)->num_rmids);
+ else
+ r->num_rmid = (*eg)->num_rmids;
+ }
+
return ret1 || ret2;
}
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index c99aa9dacfd8..9cd37be262a2 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -32,6 +32,7 @@ bool rdt_mon_capable;
#define CF(cf) ((unsigned long)(1048576 * (cf) + 0.5))
+int rdt_num_system_rmids;
static int snc_nodes_per_l3_cache = 1;
/*
@@ -350,6 +351,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
resctrl_rmid_realloc_limit = boot_cpu_data.x86_cache_size * 1024;
hw_res->mon_scale = boot_cpu_data.x86_cache_occ_scale / snc_nodes_per_l3_cache;
r->num_rmid = (boot_cpu_data.x86_cache_max_rmid + 1) / snc_nodes_per_l3_cache;
+ rdt_num_system_rmids = r->num_rmid;
hw_res->mbm_width = MBM_CNTR_WIDTH_BASE;
if (mbm_offset > 0 && mbm_offset <= MBM_CNTR_WIDTH_OFFSET_MAX)
--
2.49.0
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