linux.git/arch/x86/kernel/cpu/resctrl/core.c, branch v7.1

Merge tag 'x86_cache_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-02-11T02:24:56+00:00

Pull x86 resource control updates from Borislav Petkov:

 - Extend the resctrl machinery to support telemetry monitoring on
   Intel (Tony Luck)

   The practical usage of this is being able to tell how much energy or
   how much work can be attributed to a group of tasks tracked under a
   single idenitifier. Prepend this work with proper refactoring of
   resctrl domains handling code.

* tag 'x86_cache_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  x86,fs/resctrl: Update documentation for telemetry events
  x86/resctrl: Enable RDT_RESOURCE_PERF_PKG
  fs/resctrl: Move RMID initialization to first mount
  x86,fs/resctrl: Compute number of RMIDs as minimum across resources
  fs/resctrl: Move allocation/free of closid_num_dirty_rmid[]
  x86/resctrl: Handle number of RMIDs supported by RDT_RESOURCE_PERF_PKG
  x86/resctrl: Add energy/perf choices to rdt boot option
  x86,fs/resctrl: Handle domain creation/deletion for RDT_RESOURCE_PERF_PKG
  fs/resctrl: Refactor rmdir_mondata_subdir_allrdtgrp()
  fs/resctrl: Refactor mkdir_mondata_subdir()
  x86/resctrl: Read telemetry events
  x86/resctrl: Find and enable usable telemetry events
  x86,fs/resctrl: Add architectural event pointer
  x86,fs/resctrl: Fill in details of events for performance and energy GUIDs
  x86/resctrl: Discover hardware telemetry events
  fs/resctrl: Emphasize that L3 monitoring resource is required for summing domains
  x86,fs/resctrl: Add and initialize a resource for package scope monitoring
  x86,fs/resctrl: Add an architectural hook called for first mount
  x86,fs/resctrl: Support binary fixed point event counters
  x86,fs/resctrl: Handle events that can be read from any CPU
  ...

x86/resctrl: Fix memory bandwidth counter width for Hygon

2026-01-13T15:44:26+00:00

The memory bandwidth calculation relies on reading the hardware counter
and measuring the delta between samples. To ensure accurate measurement,
the software reads the counter frequently enough to prevent it from
rolling over twice between reads.

The default Memory Bandwidth Monitoring (MBM) counter width is 24 bits.
Hygon CPUs provide a 32-bit width counter, but they do not support the
MBM capability CPUID leaf (0xF.[ECX=1]:EAX) to report the width offset
(from 24 bits).

Consequently, the kernel falls back to the 24-bit default counter width,
which causes incorrect overflow handling on Hygon CPUs.

Fix this by explicitly setting the counter width offset to 8 bits (resulting
in a 32-bit total counter width) for Hygon CPUs.

Fixes: d8df126349da ("x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper")
Signed-off-by: Xiaochen Shen 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Tony Luck 
Reviewed-by: Reinette Chatre 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20251209062650.1536952-3-shenxiaochen@open-hieco.net

x86/resctrl: Add missing resctrl initialization for Hygon

2026-01-13T15:20:01+00:00

Hygon CPUs supporting Platform QoS features currently undergo partial resctrl
initialization through resctrl_cpu_detect() in the Hygon BSP init helper and
AMD/Hygon common initialization code. However, several critical data
structures remain uninitialized for Hygon CPUs in the following paths:

 - get_mem_config()-> __rdt_get_mem_config_amd():
     rdt_resource::membw,alloc_capable
     hw_res::num_closid

 - rdt_init_res_defs()->rdt_init_res_defs_amd():
     rdt_resource::cache
     hw_res::msr_base,msr_update

Add the missing AMD/Hygon common initialization to ensure proper Platform QoS
functionality on Hygon CPUs.

Fixes: d8df126349da ("x86/cpu/hygon: Add missing resctrl_cpu_detect() in bsp_init helper")
Signed-off-by: Xiaochen Shen 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20251209062650.1536952-2-shenxiaochen@open-hieco.net

x86/resctrl: Enable RDT_RESOURCE_PERF_PKG

2026-01-10T10:48:13+00:00

Since telemetry events are enumerated on resctrl mount the RDT_RESOURCE_PERF_PKG
resource is not considered "monitoring capable" during early resctrl initialization.
This means that the domain list for RDT_RESOURCE_PERF_PKG is not built when the CPU
hotplug notifiers are registered and run for the first time right after resctrl
initialization.

Mark the RDT_RESOURCE_PERF_PKG as "monitoring capable" upon successful telemetry
event enumeration to ensure future CPU hotplug events include this resource and
initialize its domain list for CPUs that are already online.

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

x86,fs/resctrl: Compute number of RMIDs as minimum across resources

2026-01-10T10:43:58+00:00

resctrl assumes that only the L3 resource supports monitor events, so it
simply takes the rdt_resource::num_rmid from RDT_RESOURCE_L3 as the system's
number of RMIDs.

The addition of telemetry events in a different resource breaks that
assumption.

Compute the number of available RMIDs as the minimum value across all
mon_capable resources (analogous to how the number of CLOSIDs is computed
across alloc_capable resources).

Note that mount time enumeration of the telemetry resource means that
this number can be reduced. If this happens, then some memory will
be wasted as the allocations for rdt_l3_mon_domain::mbm_states[] and
rdt_l3_mon_domain::rmid_busy_llc created during resctrl initialization will
be larger than needed.

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

x86/resctrl: Add energy/perf choices to rdt boot option

2026-01-09T22:38:32+00:00

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 parsing of the "rdt=" boot parameter to call the telemetry driver
directly to handle new "perf" and "energy" options that controls activation of
telemetry monitoring of the named type. By itself a "perf" or "energy" option
controls the forced enabling or disabling (with ! prefix) of all event groups
of the named type. A ":guid" suffix allows for fine grained control per event
group.

  [ bp: s/intel_aet_option/intel_handle_aet_option/g ]

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

x86,fs/resctrl: Handle domain creation/deletion for RDT_RESOURCE_PERF_PKG

2026-01-09T22:36:41+00:00

The L3 resource has several requirements for domains. There are per-domain
structures that hold the 64-bit values of counters, and elements to keep
track of the overflow and limbo threads.

None of these are needed for the PERF_PKG resource. The hardware counters
are wide enough that they do not wrap around for decades.

Define a new rdt_perf_pkg_mon_domain structure which just consists of the
standard rdt_domain_hdr to keep track of domain id and CPU mask.

Update resctrl_online_mon_domain() for RDT_RESOURCE_PERF_PKG. The only action
needed for this resource is to create and populate domain directories if a
domain is added while resctrl is mounted.

Similarly resctrl_offline_mon_domain() only needs to remove domain directories.

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

x86,fs/resctrl: Add architectural event pointer

2026-01-09T15:37:08+00:00

The resctrl file system layer passes the domain, RMID, and event id to the
architecture to fetch an event counter.

Fetching a telemetry event counter requires additional information that is
private to the architecture, for example, the offset into MMIO space from
where the counter should be read.

Add mon_evt::arch_priv that architecture can use for any private data related
to the event. The resctrl filesystem initializes mon_evt::arch_priv when the
architecture enables the event and passes it back to architecture when needing
to fetch an event counter.

Suggested-by: Reinette Chatre 
Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

x86/resctrl: Discover hardware telemetry events

2026-01-09T15:37:07+00:00

Each CPU collects data for telemetry events that it sends to the nearest
telemetry event aggregator either when the value of MSR_IA32_PQR_ASSOC.RMID
changes, or when a two millisecond timer expires.

There is a feature type ("energy" or "perf"), GUID, and MMIO region associated
with each aggregator. This combination links to an XML description of the
set of telemetry events tracked by the aggregator. XML files are published
by Intel in a GitHub repository¹.

The telemetry event aggregators maintain per-RMID per-event counts of the
total seen for all the CPUs. There may be multiple telemetry event aggregators
per package.

There are separate sets of aggregators for each feature type. Aggregators
in a set may have different GUIDs. All aggregators with the same feature
type and GUID are symmetric keeping counts for the same set of events for
the CPUs that provide data to them.

The XML file for each aggregator provides the following information:
0) Feature type of the events ("perf" or "energy")
1) Which telemetry events are tracked by the aggregator.
2) The order in which the event counters appear for each RMID.
3) The value type of each event counter (integer or fixed-point).
4) The number of RMIDs supported.
5) Which additional aggregator status registers are included.
6) The total size of the MMIO region for an aggregator.

Introduce struct event_group that condenses the relevant information from
an XML file. Hereafter an "event group" refers to a group of events of a
particular feature type (event_group::pfname set to "energy" or "perf") with
a particular GUID.

Use event_group::pfname to determine the feature id needed to obtain the
aggregator details. It will later be used in console messages and with the
rdt= boot parameter.

The INTEL_PMT_TELEMETRY driver enumerates support for telemetry events.
This driver provides intel_pmt_get_regions_by_feature() to list all available
telemetry event aggregators of a given feature type. The list includes the
"guid", the base address in MMIO space for the region where the event counters
are exposed, and the package id where the all the CPUs that report to this
aggregator are located.

Call INTEL_PMT_TELEMETRY's intel_pmt_get_regions_by_feature() for each event
group to obtain a private copy of that event group's aggregator data. Duplicate
the aggregator data between event groups that have the same feature type
but different GUID. Further processing on this private copy will be unique
to the event group.

  ¹https://github.com/intel/Intel-PMT

  [ bp: Zap text explaining the code, s/guid/GUID/g ]

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com

x86,fs/resctrl: Add and initialize a resource for package scope monitoring

2026-01-09T15:37:07+00:00

Add a new PERF_PKG resource and introduce package level scope for monitoring
telemetry events so that CPU hotplug notifiers can build domains at the
package granularity.

Use the physical package ID available via topology_physical_package_id()
to identify the monitoring domains with package level scope. This enables
user space to use:

  /sys/devices/system/cpu/cpuX/topology/physical_package_id

to identify the monitoring domain a CPU is associated with.

Signed-off-by: Tony Luck 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com