The "shareable_bits" and "bit_usage" resctrl files associated with cache
resources give insight into how instances of a cache is used.
Update the annotated capacity bitmasks displayed by "bit_usage" to include the
cache portions allocated for I/O via the "io_alloc" feature. "shareable_bits"
is a global bitmask of shareable cache with I/O and can thus not present the
per-domain I/O allocations possible with the "io_alloc" feature. Revise the
"shareable_bits" documentation to direct users to "bit_usage" for accurate
cache usage information.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/e02a0d424129fd7f3e45822a559b1c614ae4652a.1762995456.git.babu.moger@amd.com
The io_alloc feature in resctrl enables system software to configure the
portion of the cache allocated for I/O traffic. When supported, the
io_alloc_cbm file in resctrl provides access to capacity bitmasks (CBMs)
allocated for I/O devices.
Enable users to modify io_alloc CBMs by writing to the io_alloc_cbm resctrl
file when the io_alloc feature is enabled.
Mirror the CBMs between CDP_CODE and CDP_DATA when CDP is enabled to present
consistent I/O allocation information to user space.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/67609641b03ccfba18a8ee0bf9dbd1f3dcbecda3.1762995456.git.babu.moger@amd.com
parse_cbm() requires resource group mode and CLOSID to validate the capacity
bitmask (CBM). It is passed via struct rdtgroup in struct rdt_parse_data.
The io_alloc feature also uses CBMs to indicate which portions of cache are
allocated for I/O traffic. The CBMs are provided by user space and need to be
validated the same as CBMs provided for general (CPU) cache allocation.
parse_cbm() cannot be used as-is since io_alloc does not have rdtgroup context.
Pass the resource group mode and CLOSID directly to parse_cbm() via struct
rdt_parse_data, instead of through the rdtgroup struct, to facilitate calling
parse_cbm() to verify the CBM of the io_alloc feature.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/f8ec6ab5cf594d906a3fe75f56793d5fbd63f38f.1762995456.git.babu.moger@amd.com
Introduce the "io_alloc_cbm" resctrl file to display the capacity bitmasks
(CBMs) that represent the portions of each cache instance allocated
for I/O traffic on a cache resource that supports the "io_alloc" feature.
io_alloc_cbm resides in the info directory of a cache resource, for example,
/sys/fs/resctrl/info/L3/. Since the resource name is part of the path, it
is not necessary to display the resource name as done in the schemata file.
When CDP is enabled, io_alloc routes traffic using the highest CLOSID
associated with the CDP_CODE resource and that CLOSID becomes unusable for
the CDP_DATA resource. The highest CLOSID of CDP_CODE and CDP_DATA resources
will be kept in sync to ensure consistent user interface. In preparation for
this, access the CBMs for I/O traffic through highest CLOSID of either
CDP_CODE or CDP_DATA resource.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/55a3ff66a70e7ce8239f022e62b334e9d64af604.1762995456.git.babu.moger@amd.com
AMD's SDCIAE forces all SDCI lines to be placed into the L3 cache portions
identified by the highest-supported L3_MASK_n register, where n is the maximum
supported CLOSID.
To support this, when io_alloc resctrl feature is enabled, reserve the highest
CLOSID exclusively for I/O allocation traffic making it no longer available for
general CPU cache allocation.
Introduce user interface to enable/disable io_alloc feature and encourage users
to enable io_alloc only when running workloads that can benefit from this
functionality. On enable, initialize the io_alloc CLOSID with all usable CBMs
across all the domains.
Since CLOSIDs are managed by resctrl fs, it is least invasive to make "io_alloc
is supported by maximum supported CLOSID" part of the initial resctrl fs
support for io_alloc. Take care to minimally (only in error messages) expose
this use of CLOSID for io_alloc to user space so that this is not required from
other architectures that may support io_alloc differently in the future.
When resctrl is mounted with "-o cdp" to enable code/data prioritization,
there are two L3 resources that can support I/O allocation: L3CODE and
L3DATA. From resctrl fs perspective the two resources share a CLOSID and
the architecture's available CLOSID are halved to support this.
The architecture's underlying CLOSID used by SDCIAE when CDP is enabled is the
CLOSID associated with the CDP_CODE resource, but from resctrl's perspective
there is only one CLOSID for both CDP_CODE and CDP_DATA. CDP_DATA is thus not
usable for general (CPU) cache allocation nor I/O allocation.
Keep the CDP_CODE and CDP_DATA I/O alloc status in sync to avoid any confusion
to user space. That is, enabling io_alloc on CDP_CODE does so on CDP_DATA and
vice-versa, and keep the I/O allocation CBMs of CDP_CODE and CDP_DATA in sync.
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/c7d3037795e653e22b02d8fc73ca80d9b075031c.1762995456.git.babu.moger@amd.com
Introduce the "io_alloc" resctrl file to the "info" area of a cache resource,
for example /sys/fs/resctrl/info/L3/io_alloc. "io_alloc" indicates support for
the "io_alloc" feature that allows direct insertion of data from I/O
devices into the cache.
Restrict exposing support for "io_alloc" to the L3 resource that is the only
resource where this feature can be backed by AMD's L3 Smart Data Cache
Injection Allocation Enforcement (SDCIAE). With that, the "io_alloc" file is
only visible to user space if the L3 resource supports "io_alloc".
Doing so makes the file visible for all cache resources though, for example
also L2 cache (if it supports cache allocation). As a consequence, add
capability for file to report expected "enabled" and "disabled", as well as
"not supported".
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/e8b116a8f424128b227734bb1d433c14af478d90.1762995456.git.babu.moger@amd.com
When "mbm_event" counter assignment mode is enabled, the architecture requires
a counter ID to read the event data.
Introduce an is_mbm_cntr field in struct rmid_read to indicate whether counter
assignment mode is in use.
Update the logic to call resctrl_arch_cntr_read() and resctrl_arch_reset_cntr()
when the assignment mode is active. Report 'Unassigned' in case the user attempts
to read an event without assigning a hardware counter.
Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com
Running resctrl_tests on an SNC-2 system with lockdep debugging enabled
triggers several warnings with following trace:
WARNING: CPU: 0 PID: 1914 at kernel/cpu.c:528 lockdep_assert_cpus_held
...
Call Trace:
__mon_event_count
? __lock_acquire
? __pfx___mon_event_count
mon_event_count
? __pfx_smp_mon_event_count
smp_mon_event_count
smp_call_on_cpu_callback
get_cpu_cacheinfo_level() called from __mon_event_count() requires CPU hotplug
lock to be held. The hotplug lock is indeed held during this time, as
confirmed by the lockdep_assert_cpus_held() within mon_event_read() that calls
mon_event_count() via IPI, but the lockdep tracking is not able to follow the
IPI.
Fresh CPU cache information via get_cpu_cacheinfo_level() from
__mon_event_count() was added to support the fix for the issue where resctrl
inappropriately maintained links to L3 cache information that will be stale in
the case when the associated CPU goes offline.
Keep the cacheinfo ID in struct rdt_mon_domain to ensure that resctrl does not
maintain stale cache information while CPUs can go offline. Return to using
a pointer to the L3 cache information (struct cacheinfo) in struct rmid_read,
rmid_read::ci. Initialize rmid_read::ci before the IPI where it is used. CPU
hotplug lock is held across rmid_read::ci initialization and use to ensure
that it points to accurate cache information.
Fixes: 594902c986 ("x86,fs/resctrl: Remove inappropriate references to cacheinfo in the resctrl subsystem")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
In the resctrl subsystem's Sub-NUMA Cluster (SNC) mode, the rdt_mon_domain
structure representing a NUMA node relies on the cacheinfo interface
(rdt_mon_domain::ci) to store L3 cache information (e.g., shared_cpu_map)
for monitoring. The L3 cache information of a SNC NUMA node determines
which domains are summed for the "top level" L3-scoped events.
rdt_mon_domain::ci is initialized using the first online CPU of a NUMA
node. When this CPU goes offline, its shared_cpu_map is cleared to contain
only the offline CPU itself. Subsequently, attempting to read counters
via smp_call_on_cpu(offline_cpu) fails (and error ignored), returning
zero values for "top-level events" without any error indication.
Replace the cacheinfo references in struct rdt_mon_domain and struct
rmid_read with the cacheinfo ID (a unique identifier for the L3 cache).
rdt_domain_hdr::cpu_mask contains the online CPUs associated with that
domain. When reading "top-level events", select a CPU from
rdt_domain_hdr::cpu_mask and utilize its L3 shared_cpu_map to determine
valid CPUs for reading RMID counter via the MSR interface.
Considering all CPUs associated with the L3 cache improves the chances
of picking a housekeeping CPU on which the counter reading work can be
queued, avoiding an unnecessary IPI.
Fixes: 328ea68874 ("x86/resctrl: Prepare for new Sub-NUMA Cluster (SNC) monitor files")
Signed-off-by: Qinyun Tan <qinyuntan@linux.alibaba.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/20250530182053.37502-2-qinyuntan@linux.alibaba.com
