linux-toradex.git/arch/x86/kernel/cpu/resctrl, branch master

x86/resctrl: Fix SNC detection

2026-03-04T15:35:09+00:00

Now that the x86 topology code has a sensible nodes-per-package
measure, that does not depend on the online status of CPUs, use this
to divinate the SNC mode.

Note that when Cluster on Die (CoD) is configured on older systems this
will also show multiple NUMA nodes per package. Intel Resource Director
Technology is incomaptible with CoD. Print a warning and do not use the
fixup MSR_RMID_SNC_CONFIG.

Signed-off-by: Tony Luck 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Ingo Molnar 
Tested-by: Zhang Rui 
Tested-by: Chen Yu 
Link: https://patch.msgid.link/aaCxbbgjL6OZ6VMd@agluck-desk3
Link: https://patch.msgid.link/20260303110100.367976706@infradead.org

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: Handle number of RMIDs supported by RDT_RESOURCE_PERF_PKG

2026-01-10T10:20:14+00:00

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 MSR_IA32_PQR_ASSOC.
   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_rmid.

3) The number of "hardware 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 by intel_pmt_get_regions_by_feature().

Event groups with insufficient "hardware counters" to track all RMIDs are
difficult for users to use, since the system may reassign "hardware counters"
at any time. This means that users cannot reliably collect two consecutive
event counts to compute the rate at which events are occurring.

Disable such event groups by default. The user may override this with
a command line "rdt=" option. In this case limit an under-resourced event
group's number of possible monitor resource groups to the lowest number of
"hardware counters".

Scan all enabled event groups and assign the RDT_RESOURCE_PERF_PKG resource
"num_rmid" value to the smallest of these values as this value will be used
later to compare against the number of RMIDs supported by other resources to
determine how many monitoring resource groups are supported.

N.B. Change type of resctrl_mon::num_rmid to u32 to match its usage and the
type of event_group::num_rmid so that min(r->num_rmid, e->num_rmid) won't
complain about mixing signed and unsigned types.

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/resctrl: Read telemetry events

2026-01-09T22:02:57+00:00

Introduce intel_aet_read_event() to read telemetry events for resource
RDT_RESOURCE_PERF_PKG. There may be multiple aggregators tracking each
package, so scan all of them and add up all counters. Aggregators may return
an invalid data indication if they have received no records for a given RMID.
The user will see "Unavailable" if none of the aggregators on a package
provide valid counts.

Resctrl now uses readq() so depends on X86_64. Update Kconfig.

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