kernel/linux.git/fs/resctrl/internal.h, branch v7.0-rc7

fs/resctrl: Move RMID initialization to first mount

2026-01-10T10:46:48+00:00

L3 monitor features are enumerated during resctrl initialization and rmid_ptrs[] that tracks all RMIDs and depends on the number of supported RMIDs is allocated during this time. Telemetry monitor features are enumerated during first resctrl mount and may support a different number of RMIDs compared to L3 monitor features. Delay allocation and initialization of rmid_ptrs[] until first mount. Since the number of RMIDs cannot change on later mounts, keep the same set of rmid_ptrs[] until resctrl_exit(). This is required because the limbo handler keeps running after resctrl is unmounted and needs to access rmid_ptrs[] as it keeps tracking busy RMIDs after unmount. Rename routines to match what they now do: dom_data_init() -> setup_rmid_lru_list() dom_data_exit() -> free_rmid_lru_list() 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

fs/resctrl: Emphasize that L3 monitoring resource is required for summing domains

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

The feature to sum event data across multiple domains supports systems with Sub-NUMA Cluster (SNC) mode enabled. The top-level monitoring files in each "mon_L3_XX" directory provide the sum of data across all SNC nodes sharing an L3 cache instance while the "mon_sub_L3_YY" sub-directories provide the event data of the individual nodes. SNC is only associated with the L3 resource and domains and as a result the flow handling the sum of event data implicitly assumes it is working with the L3 resource and domains. Reading of telemetry events does not require to sum event data so this feature can remain dedicated to SNC and keep the implicit assumption of working with the L3 resource and domains. Add a WARN to where the implicit assumption of working with the L3 resource is made and add comments on how the structure controlling the event sum feature is used. 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,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

x86,fs/resctrl: Support binary fixed point event counters

2026-01-05T15:10:41+00:00

resctrl assumes that all monitor events can be displayed as unsigned decimal integers. Hardware architecture counters may provide some telemetry events with greater precision where the event is not a simple count, but is a measurement of some sort (e.g. Joules for energy consumed). Add a new argument to resctrl_enable_mon_event() for architecture code to inform the file system that the value for a counter is a fixed-point value with a specific number of binary places. Only allow architecture to use floating point format on events that the file system has marked with mon_evt::is_floating_point which reflects the contract with user space on how the event values are displayed. Display fixed point values with values rounded to ceil(binary_bits * log10(2)) decimal places. Special case for zero binary bits to print "{value}.0". 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 events that can be read from any CPU

2026-01-05T14:38:07+00:00

resctrl assumes that monitor events can only be read from a CPU in the cpumask_t set of each domain. This is true for x86 events accessed with an MSR interface, but may not be true for other access methods such as MMIO. Introduce and use flag mon_evt::any_cpu, settable by architecture, that indicates there are no restrictions on which CPU can read that event. This flag is not supported by the L3 event reading that requires to be run on a CPU that belongs to the L3 domain of the event being read. 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

fs/resctrl: Make event details accessible to functions when reading events

2026-01-05T14:25:22+00:00

Reading monitoring event data from MMIO requires more context than the event id to be able to read the correct memory location. struct mon_evt is the appropriate place for this event specific context. Prepare for addition of extra fields to struct mon_evt by changing the calling conventions to pass a pointer to the mon_evt structure instead of just the event id. 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: Rename some L3 specific functions

2026-01-05T10:21:55+00:00

With the arrival of monitor events tied to new domains associated with a different resource it would be clearer if the L3 resource specific functions are more accurately named. Rename three groups of functions: Functions that allocate/free architecture per-RMID MBM state information: arch_domain_mbm_alloc() -> l3_mon_domain_mbm_alloc() mon_domain_free() -> l3_mon_domain_free() Functions that allocate/free filesystem per-RMID MBM state information: domain_setup_mon_state() -> domain_setup_l3_mon_state() domain_destroy_mon_state() -> domain_destroy_l3_mon_state() Initialization/exit: rdt_get_mon_l3_config() -> rdt_get_l3_mon_config() resctrl_mon_resource_init() -> resctrl_l3_mon_resource_init() resctrl_mon_resource_exit() -> resctrl_l3_mon_resource_exit() Ensure kernel-doc descriptions of these functions' return values are present and correctly formatted. 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: Rename struct rdt_mon_domain and rdt_hw_mon_domain

2026-01-05T10:17:25+00:00

The upcoming telemetry event monitoring is not tied to the L3 resource and will have a new domain structure. Rename the L3 resource specific domain data structures to include "l3_" in their names to avoid confusion between the different resource specific domain structures: rdt_mon_domain -> rdt_l3_mon_domain rdt_hw_mon_domain -> rdt_hw_l3_mon_domain No functional change. 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: Use struct rdt_domain_hdr when reading counters

2026-01-05T10:08:58+00:00

Convert the whole call sequence from mon_event_read() to resctrl_arch_rmid_read() to pass resource independent struct rdt_domain_hdr instead of an L3 specific domain structure to prepare for monitoring events in other resources. This additional layer of indirection obscures which aspects of event counting depend on a valid domain. Event initialization, support for assignable counters, and normal event counting implicitly depend on a valid domain while summing of domains does not. Split summing domains from the core event counting handling to make their respective dependencies obvious. 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