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Message-ID: <20251204205404.12763-25-tony.luck@intel.com>
Date: Thu, 4 Dec 2025 12:53:54 -0800
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>,
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 v15 24/32] x86/resctrl: Add energy/perf choices to rdt boot option
Legacy resctrl features are enumerated by X86_FEATURE_* flags. These may be
overridden by quirks to disable features in the case of errata. Users can
use kernel command line options to either disable a feature, or to force
enable a feature that was disabled by a quirk.
A different approach is needed for hardware features that do not have an
X86_FEATURE_* flag.
Update the parse loop of the "rdt=" boot option with a call to intel_aet_option()
to handles "perf" and "energy" options. Prefixing an option with "!" force
disables a feature. A ":guid" suffix allows for fine grain control per-guid.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
.../admin-guide/kernel-parameters.txt | 7 +++-
arch/x86/kernel/cpu/resctrl/internal.h | 2 ++
arch/x86/kernel/cpu/resctrl/core.c | 2 ++
arch/x86/kernel/cpu/resctrl/intel_aet.c | 34 +++++++++++++++++++
4 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2b465eab41a1..cc9d2800abeb 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6217,9 +6217,14 @@
rdt= [HW,X86,RDT]
Turn on/off individual RDT features. List is:
cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
- mba, smba, bmec, abmc, sdciae.
+ mba, smba, bmec, abmc, sdciae, energy[:guid],
+ perf[:guid].
E.g. to turn on cmt and turn off mba use:
rdt=cmt,!mba
+ To turn off all energy telemetry monitoring and ensure that
+ perf telemetry monitoring associated with guid 0x12345
+ is enabled use:
+ rdt=!energy,perf:0x12345
reboot= [KNL]
Format (x86 or x86_64):
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 3b228b241fb2..df09091f7c6c 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -236,6 +236,7 @@ void __exit intel_aet_exit(void);
int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64 *val);
void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
struct list_head *add_pos);
+bool intel_aet_option(bool force_off, char *tok);
#else
static inline bool intel_aet_get_events(void) { return false; }
static inline void __exit intel_aet_exit(void) { }
@@ -246,6 +247,7 @@ static inline int intel_aet_read_event(int domid, u32 rmid, void *arch_priv, u64
static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
struct list_head *add_pos) { }
+static inline bool intel_aet_option(bool force_off, char *tok) { return false; }
#endif
#endif /* _ASM_X86_RESCTRL_INTERNAL_H */
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 283d653002a2..960974ffa866 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -820,6 +820,8 @@ static int __init set_rdt_options(char *str)
force_off = *tok == '!';
if (force_off)
tok++;
+ if (intel_aet_option(force_off, tok))
+ continue;
for (o = rdt_options; o < &rdt_options[NUM_RDT_OPTIONS]; o++) {
if (strcmp(tok, o->name) == 0) {
if (force_off)
diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
index 8fcd72fca81f..fec4bb781f82 100644
--- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
+++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
@@ -59,6 +59,10 @@ struct pmt_event {
* data for all telemetry regions of type @pfname.
* Valid if the system supports the event group,
* NULL otherwise.
+ * @force_off: True when "rdt" command line disables this @guid
+ * or architecture code disables this @guid.
+ * @force_on: True when "rdt" command line overrides disable of
+ * this @guid.
* @guid: Unique number per XML description file.
* @mmio_size: Number of bytes of MMIO registers for this group.
* @num_events: Number of events in this group.
@@ -68,6 +72,7 @@ struct event_group {
/* Data fields for additional structures to manage this group. */
const char *pfname;
struct pmt_feature_group *pfg;
+ bool force_off, force_on;
/* Remaining fields initialized from XML file. */
u32 guid;
@@ -122,6 +127,32 @@ static struct event_group *known_event_groups[] = {
_peg < &known_event_groups[ARRAY_SIZE(known_event_groups)]; \
_peg++)
+bool intel_aet_option(bool force_off, char *tok)
+{
+ struct event_group **peg;
+ bool ret = false;
+ u32 guid = 0;
+ char *name;
+
+ name = strsep(&tok, ":");
+ if (tok && kstrtou32(tok, 16, &guid))
+ return false;
+
+ for_each_event_group(peg) {
+ if (strcmp(name, (*peg)->pfname))
+ continue;
+ if (guid && (*peg)->guid != guid)
+ continue;
+ if (force_off)
+ (*peg)->force_off = true;
+ else
+ (*peg)->force_on = true;
+ ret = true;
+ }
+
+ return ret;
+}
+
/*
* Clear the address field of regions that did not pass the checks in
* skip_telem_region() so they will not be used by intel_aet_read_event().
@@ -173,6 +204,9 @@ static bool enable_events(struct event_group *e, struct pmt_feature_group *p)
struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_PERF_PKG].r_resctrl;
int skipped_events = 0;
+ if (e->force_off)
+ return false;
+
if (!group_has_usable_regions(e, p))
return false;
--
2.51.1
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