linux.git/fs/resctrl/monitor.c, branch v7.2-rc1

fs/resctrl: Continue counter allocation after failure

2026-05-08T10:07:43+00:00

In mbm_event mode, with mbm_assign_on_mkdir set to 1, when a user creates a
new CTRL_MON or MON group resctrl attempts to allocate counters for each of
the supported MBM events on each resctrl domain. As counters are limited,
such allocation may fail and when it does counter allocations for the
remaining domains are skipped even if the domains have available counters.

Because of that, the user needs to view the resource group'smbm_L3_assignments
file to get an accurate view of counter assignment in a new resource group and
then manually create counters in the skipped domains with available counters.

Writes to mbm_L3_assignments using the wildcard format, :*=e, also skip
counter allocation in other domains after a counter allocation failure.

When handling a request to create counters in all domains it is unnecessary
for a counter allocation in one domain to prevent counter allocation in
other domains. Always attempt to allocate all the counters requested.

  [ bp: Massage commit message. ]

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Babu Moger 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

fs/resctrl: Add monitor property 'mbm_cntr_assign_fixed'

2026-05-07T14:29:14+00:00

Commit

  3b497c3f4f04 ("fs/resctrl: Introduce the interface to display monitoring modes")

introduced CONFIG_RESCTRL_ASSIGN_FIXED but left adding the Kconfig
entry until it was necessary. The counter assignment mode is fixed in
MPAM, even when there are assignable counters, and so addressing this
is needed to support MPAM.

To avoid the burden of another Kconfig entry, replace
CONFIG_RESCTRL_ASSIGN_FIXED with a new property in 'struct resctrl_mon',
'mbm_cntr_assign_fixed' to be set by the architecture.

Do not request the architecture to change the counter assignment mode if it
does not support doing so. Provide insight to user space about why such a
request fails.

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Babu Moger 
Reviewed-by: Reinette Chatre 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

x86,fs/resctrl: Create 'event_filter' files read only if they're not configurable

2026-05-06T17:06:57+00:00

When the counter assignment mode is mbm_event resctrl assumes the MBM
events are configurable and exposes the 'event_filter' files. These files
live at info/L3_MON/event_configs//event_filter and are used to
display and set the event configuration.

The MPAM architecture has support for configuring the memory bandwidth
utilization (MBWU) counters to only count reads or only count
writes. However, in MPAM, this event filtering support is optional in the
hardware (and not yet implemented in the MPAM driver) but MBM counter
assignment is always possible for MPAM MBWU counters.

In order to support mbm_event mode with MPAM, create the 'event_filter'
files read only if the event configuration can't be changed. A user can
still chmod the file and so also return early with an error from
event_filter_write().

Introduce a new monitor property, mbm_cntr_configurable, to indicate
whether or not assignable MBM counters are configurable. On x86, set this
to true whenever mbm_cntr_assignable is true to keep existing behaviour.

Signed-off-by: Ben Horgan 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Reinette Chatre 
Reviewed-by: Babu Moger 
Tested-by: Babu Moger 
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com

fs/resctrl: Add missing return value descriptions

2026-04-07T19:01:22+00:00

Using the stricter "./tools/docs/kernel-doc -Wall -v" to verify proper
formatting of documentation comments includes warnings related to return
markup on functions that are omitted during the default verification
checks. This stricter verification reports a couple of missing return
descriptions in resctrl:

    Warning: .../fs/resctrl/rdtgroup.c:1536 No description found for return value of 'rdtgroup_cbm_to_size'
    Warning: .../fs/resctrl/rdtgroup.c:3131 No description found for return value of 'mon_get_kn_priv'
    Warning: .../fs/resctrl/rdtgroup.c:3523 No description found for return value of 'cbm_ensure_valid'
    Warning: .../fs/resctrl/monitor.c:238 No description found for return value of 'resctrl_find_cleanest_closid'

Add the missing return descriptions.

Signed-off-by: Reinette Chatre 
Signed-off-by: Borislav Petkov (AMD) 
Link: https://patch.msgid.link/1c50b9f7c73251c007133590986f127e1af57780.1775576382.git.reinette.chatre@intel.com

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using

    git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook

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

fs/resctrl: Move allocation/free of closid_num_dirty_rmid[]

2026-01-10T10:33:14+00:00

closid_num_dirty_rmid[] and rmid_ptrs[] are allocated together during resctrl
initialization and freed together during resctrl exit.

Telemetry events are enumerated on resctrl mount so only at resctrl mount will
the number of RMID supported by all monitoring resources and needed as size
for rmid_ptrs[] be known.

Separate closid_num_dirty_rmid[] and rmid_ptrs[] allocation and free in
preparation for rmid_ptrs[] to be allocated on resctrl mount.

Keep the rdtgroup_mutex protection around the allocation and free of
closid_num_dirty_rmid[] as ARM needs this to guarantee memory ordering.

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

x86/resctrl: Find and enable usable telemetry events

2026-01-09T22:02:45+00:00

Every event group has a private copy of the data of all telemetry event
aggregators (aka "telemetry regions") tracking its feature type. Included
may be regions that have the same feature type but tracking different GUID
from the event group's.

Traverse the event group's telemetry region data and mark all regions that
are not usable by the event group as unusable by clearing those regions'
MMIO addresses. A region is considered unusable if:
1) GUID does not match the GUID of the event group.
2) Package ID is invalid.
3) The enumerated size of the MMIO region does not match the expected
   value from the XML description file.

Hereafter any telemetry region with an MMIO address is considered valid for
the event group it is associated with.

Enable all the event group's events as long as there is at least one usable
region from where data for its events can be read. Enabling of an event can
fail if the same event has already been enabled as part of another event
group. It should never happen that the same event is described by different
GUID supported by the same system so just WARN (via resctrl_enable_mon_event())
and skip the event.

Note that it is architecturally possible that some telemetry events are only
supported by a subset of the packages in the system. It is not expected that
systems will ever do this. If they do the user will see event files in resctrl
that always return "Unavailable".

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