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resctrl fs commands are becoming more powerful with, for example, a user able
to use syntax like '*' to make broad configuration changes. Such commands that
span multiple domains may result in more than one message printed to the
last_cmd_status buffer with more planned.
Issue "[truncated]" when displaying the last_cmd_status buffer to communicate
if it overflowed. Upon encountering this, user space is expected to combine
details about the failure found in info/last_cmd_status with related resctrl
files to learn the accurate system state after the command failure.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://patch.msgid.link/eb3d1aaa41d1f2bf6b1bb26ceafd52f04912121d.1782857711.git.reinette.chatre@intel.com
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User space expects last_cmd_status to contain additional information if any
resctrl command fails.
A resctrl command may be blocked on the rdtgroup_mutex waiting for another
command to finish and find that once the mutex is available that the resource
group has since been deleted.
In this scenario the command will fail while last_cmd_status contains either
"ok" if the last_cmd_status buffer is empty or an outdated error from
a previous command failure if last_cmd_status buffer has content.
Include clearing of last_cmd_status buffer as part of rdtgroup_kn_lock_live()
that is used to obtain access and needed locking to a resource group before
attempting a command on the group.
With the last_cmd_status buffer ready, provide an appropriate message to user
space if the resource group has been deleted.
No last_cmd_status treatment is needed for the remaining failure of
rdtgroup_kn_lock_live() encountering a non-existent resource group since that
could only occur during an attempt to obtain a resource group lock on a file
in info/ which is an invalid usage.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://patch.msgid.link/9982141ec6f3ec18e0c53d7feabb19651583cf0e.1782857711.git.reinette.chatre@intel.com
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info/last_cmd_status is intended to contain more information if a write to
any resctrl file fails. Writes to max_threshold_occupancy did not receive
last_cmd_status support during initial last_cmd_status enabling. Add it now.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://patch.msgid.link/dfc60cf5324e15612db075b0987bd89c490fbad5.1782857711.git.reinette.chatre@intel.com
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A pattern of usage of last_cmd_status was introduced during its enabling in
commit
c377dcfbee80 ("x86/intel_rdt: Add diagnostics when writing the schemata file")
and since copied throughout resctrl to result in the following custom:
..._write()
{
/* Early parsing of input, exit on failure. */
/* Obtain rdtgroup_mutex */
rdt_last_cmd_clear(); /* Clear last_cmd_status buffer */
/*
* Act on user command, failures result in detail
* error message in last_cmd_status buffer via
* rdt_last_cmd_puts()/rdt_last_cmd_printf().
*/
/* Release rdtgroup_mutex */
}
If resctrl exits with failure during early parsing of input there are two
possible scenarios:
- The last_cmd_status buffer is empty and a user's read of
info/last_cmd_status returns "ok".
- The last_cmd_status buffer contains details from an earlier ...write()
failure and a user's read of info/last_cmd_status returns this outdated
error description.
Writing to a resctrl file is considered a "resctrl command" and the resctrl
documentation states the following about the last_cmd_status file:
"If the command failed, it will provide more information that can be
conveyed in the error returns from file operations."
Neither of the current scenarios is correct behavior.
Move early input parsing to be done with rdtgroup_mutex held after the
last_cmd_status buffer is cleared. Let info/last_cmd_status be accurate
when an error is encountered during parsing of user command.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://patch.msgid.link/c9eba0ef3b9a72b845b4ae02ecd7c098ed8bf06f.1782857711.git.reinette.chatre@intel.com
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The mbm_handle_overflow() and cqm_handle_limbo() workers read event counters
and may sleep while doing so. They are scheduled via delayed_work embedded in
struct rdt_l3_mon_domain. Architecture allocates and frees these domains from
CPU hotplug callbacks under cpus_write_lock(), and the workers acquire
cpus_read_lock() to keep the domain alive across their access.
A use-after-free can occur when a worker is blocked waiting for
cpus_read_lock() while the hotplug core holds cpus_write_lock(): the
architecture frees the rdt_l3_mon_domain that contains the worker's
work_struct. When the worker unblocks, the container_of() it performs on the
embedded work pointer dereferences freed memory.
Drop cpus_read_lock() from the workers and instead drain pending and in-flight
work synchronously before the architecture can free the domain. Since
architecture offlines the domain under cpus_write_lock() after it has been
unlinked from the RCU list and a grace period has elapsed, no new work can be
scheduled. The cancel only needs to wait out existing work. Drop
rdtgroup_mutex during CPU offline around cancel_delayed_work_sync() so that
a worker waiting on the mutex can complete before re-pinning the work on
a different CPU.
When offlining a CPU the architecture may iterate over resources in any order.
For example, the MBA control domain may be offlined before or after
a corresponding L3 monitor domain. Ensure that resctrl fs cancels the workers
no matter what order the architecture offlines the domains.
Fixes: 24247aeeabe9 ("x86/intel_rdt/cqm: Improve limbo list processing")
Closes: https://sashiko.dev/#/patchset/20260429184858.36423-1-tony.luck%40intel.com # [1]
Reported-by: Sashiko <sashiko-bot@kernel.org>
Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/3f0e0752deb3421606dfc4600f0ab3a4ae098cd7.1783963505.git.reinette.chatre@intel.com
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resctrl provides files under the info/ directory to expose global
configuration and capabilities to userspace. These files are instantiated
statically during filesystem mount and expose data associated with internal
schema structures via kernfs private pointers.
A potential deadlock exists between userspace readers of these info files
and the unmount filesystem teardown process. Reading an info file invokes
kernfs which acquires an active reference, after which the handler typically
attempts to acquire the rdtgroup_mutex.
Concurrently, unmounting the filesystem holds the rdtgroup_mutex and then
attempts to recursively remove the info kernfs nodes involving kernfs_drain()
which blocks until all active references are released.
Another problem exists where info files might be accessed from an outdated
mount if the filesystem is unmounted and remounted during a reader's
execution, leading to a use-after-free when reading the now-deleted private
schema data.
Introduce info_kn_lock() and info_kn_unlock() helpers to coordinate locking
across all info handlers. These helpers mirror similar logic used by resource
group handlers by deliberately breaking the kernfs active protection before
attempting to acquire the rdtgroup_mutex, preventing the deadlock.
To guard against the vulnerability from rapid mount cycling, info_kn_lock()
securely walks the parent lineage of the kernfs node under an RCU section to
confirm the node belongs to the globally active root before permitting the
operation to proceed. Convert all info file handlers to use this helper and
only de-reference the schema after it is determined safe to do so.
Make no attempt to output an error message to last_cmd_status on failure
since failure implies there is no filesystem with which to display the error
to user space.
[ bp: Massage commit message. ]
Closes: https://sashiko.dev/#/patchset/20260515193944.15114-1-tony.luck%40intel.com?part=3
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: GitHub_Copilot:gemini-3.1-pro
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://patch.msgid.link/0b5238486bd058704d908d39a75aff2815bd18aa.1783963505.git.reinette.chatre@intel.com
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A struct rdtgroup is reference counted via rdtgroup::waitcount. Callers that
need the structure to remain valid across a sleep (while waiting on acquiring
rdtgroup_mutex) take a reference with rdtgroup_kn_get() and release it with
rdtgroup_kn_put().
The release path is intended to serve as the fallback freer: if the count
drops to zero and the group has already been marked RDT_DELETED,
rdtgroup_kn_put() frees the structure.
The bulk teardown paths free_all_child_rdtgrp() and rmdir_all_sub() resulting
from a resctrl directory remove or resctrl fs unmount act as the primary
freer: they hold rdtgroup_mutex and free each rdtgroup whose waitcount is
zero, otherwise they set RDT_DELETED and leave the freeing to the last waiter.
These two freers race. rdtgroup_kn_put() commits waitcount == 0 with
atomic_dec_and_test() outside rdtgroup_mutex, then reads rdtgroup::flags.
Between those two operations a concurrent caller of free_all_child_rdtgrp()
or rmdir_all_sub() (which holds the mutex) can observe waitcount == 0 via
atomic_read(), call rdtgroup_remove(), and kfree() the structure.
The subsequent read of rdtgroup::flags in rdtgroup_kn_put() is then
a use-after-free, and the structure may even be freed twice if the freed
memory happens to satisfy the RDT_DELETED flag check.
Replace the bare atomic_dec_and_test() with atomic_dec_and_mutex_lock() so
that the decrement-to-zero takes rdtgroup_mutex before the count becomes
globally visible. The inspection of rdtgroup::flags then runs under the same
mutex held by the bulk freers, making the two paths mutually exclusive.
The common case where the count does not reach zero remains lock-free. Defer
kernfs_unbreak_active_protection() until after the mutex is dropped since
kernfs active protections functionally wrap rdtgroup_mutex. Remove resource
group, which in turn drops its kernfs reference, after kernfs protection is
restored.
[ bp: Split the commit messsages into smaller, easier-parseable paragraphs. ]
Fixes: b8511ccc75c0 ("x86/resctrl: Fix use-after-free when deleting resource groups")
Closes: https://sashiko.dev/#/patchset/20260515193944.15114-1-tony.luck%40intel.com?part=1
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: GitHub_Copilot:gemini-3.1-pro
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://patch.msgid.link/8d028bbea582dc382a4cc166b235f75bd5901aea.1783963505.git.reinette.chatre@intel.com
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rdt_get_tree() acquires rdtgroup_mutex before calling kernfs_get_tree(). If
superblock setup fails inside kernfs_get_tree(), the VFS calls .kill_sb()
(rdt_kill_sb()) on the same thread before kernfs_get_tree() returns.
rdt_kill_sb() unconditionally attempts to acquire rdtgroup_mutex and
deadlock occurs.
Since mount failure resulting from kernfs_get_tree() already calls the
resctrl fs unmount handler (rdt_kill_sb()) let both call the same helper
to make it clear both paths perform the same cleanup.
Call kernfs_get_tree() outside of locks. If kernfs_get_tree() fails and
ctx->kfc.new_sb_created is set, then rdt_kill_sb() has already been called
and no further cleanup is needed.
kernfs_get_tree() may set ctx->kfc.new_sb_created and then fail to obtain
an inode for the new kn, causing the rdt_kill_sb() path to run with one fewer
reference than required for the root to remain accessible in kernfs_kill_sb().
Add an extra hold on rdtgroup_default.kn to defend against this scenario
and ensure the root can be dereferenced safely from kernfs_kill_sb().
Dropping locks before kernfs_get_tree() creates a window where CPU hotplug
callbacks can race with the mount operation. Specifically, an online event
observing resctrl_mounted == true could concurrently append directories to
the unactivated kernfs tree, allocate mon_data structures, and arm background
workers.
This concurrency is safe because the mount has not yet returned to the VFS,
meaning userspace cannot interact with these transient files. If
kernfs_get_tree() subsequently fails, the standard resctrl_unmount() teardown
safely manages the concurrent modifications: any dynamically generated kernfs
nodes are removed, and the associated memory is freed. Any background
workers spawned by the hotplug event will naturally exit without re-arming
when they acquire rdtgroup_mutex and observe resctrl_mounted == false.
Fixes: 5ff193fbde20 ("x86/intel_rdt: Add basic resctrl filesystem support")
Closes: https://sashiko.dev/#/patchset/20260429184858.36423-1-tony.luck%40intel.com [1]
Reported-by: Sashiko <sashiko-bot@kernel.org>
Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Link: https://patch.msgid.link/fe701825d7f538a6bbac6732230004050300c93e.1783963505.git.reinette.chatre@intel.com
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rdt_get_tree() manages resctrl fs mount and rdt_kill_sb() manages resctrl
fs unmount.
There is significant overlap between error cleanup during resctrl mount
failure and cleanup on resctrl unmount yet the cleanup is not done
consistently in these two flows.
Pull some cleanup functions before rdt_get_tree() in preparation for a new
helper that can be shared between mount and unmount.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Link: https://patch.msgid.link/af10101be95679e1d69ce4efc3edf980a6cc37cc.1783963505.git.reinette.chatre@intel.com
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rdt_resource::ctrl_domains and rdt_resource::mon_domains are RCU lists with
entries added and removed by architecture from CPU hotplug callbacks that are
run with cpus_write_lock() held. These lists can be traversed safely from
resctrl fs by either holding cpus_read_lock() or relying on an RCU read-side
critical section.
resctrl fs traversals of rdt_resource::ctrl_domains and
rdt_resource::mon_domains are done using list_for_each_entry() with
cpus_read_lock() held. Similarly, x86 architecture callbacks use
list_for_each_entry() expecting that resctrl fs makes the call with
cpus_read_lock() held. Inconsistently, a lockdep_assert_cpus_held() precedes
the list_for_each_entry() call with varying distance to document this safe RCU
list traversal.
In preparation for an upcoming traversal of rdt_resource::ctrl_domains that
needs to be done from RCU read-side critical section there is a requirement
for developers to always know exactly in which context the list is being
traversed.
Replace the list_for_each_entry() traversals of RCU list with
list_for_each_entry_rcu() to document that an RCU list is being traversed
while making use of the built-in lockdep expression that additionally
documents that it is cpus_read_lock() that enables the list to be
traversed from non-RCU protection. Only revert to documenting the
safety of traversal using a comment when lockdep does not have needed
visibility in functions called via smp_call*().
The lockdep expression within list_for_each_entry_rcu() depends on
RCU_EXPERT that is not set in a typical debug kernel so keep the existing
lockdep_assert_cpus_held() that is active with CONFIG_LOCKDEP=y found in
typical debug kernel.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/d9373f8da8ffde667740e186ffc96ab69628ac9a.1783963505.git.reinette.chatre@intel.com
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A pseudo-locked group's RMID is freed when it is created. On unmount
rmdir_all_sub() unconditionally frees all RMID of all groups, resulting
in a double-free of the pseudo-locked group's RMID. The consequence of this
is that the original free results in the pseudo-locked group's RMID being
added to the rmid_free_lru linked list and the second free then attempts
to add the same RMID entry to the rmid_free_lru again.
Do not double-free a pseudo-locked group's RMID.
Fixes: e0bdfe8e36f3 ("x86/intel_rdt: Support creation/removal of pseudo-locked region")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/551432dd7e624a862b8e58314c38aaba0afff3e9.1783377598.git.reinette.chatre@intel.com
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During unmount or failure teardown all mon_data structures that contain
monitoring event file private data are freed after which kernfs nodes are
removed. However, the RDT_DELETED flag is never set for the statically
allocated default resource group.
A concurrent reader of an event file associated with the default resource
group may, after dropping kernfs active protection, block on rdtgroup_mutex
while unmount proceeds to free the file private data and destroy the kernfs
node without waiting for the reader.
When the mutex is released, the reader wakes up, observes that RDT_DELETED
is not set for the default group, and dereferences the already-freed
file private data.
The scenario can be depicted as follows:
CPU0 CPU1
/*
* Default resource group's
* monitoring data accessible via
* kernfs file with kernfs_node::priv
* pointing to a struct mon_data.
* User opens the file for reading.
*/
rdtgroup_mondata_show() /* arch encounters fatal error */
rdtgroup_kn_lock_live() resctrl_exit()
atomic_inc(&rdtgroup_default.waitcount) cpus_read_lock()
kernfs_break_active_protection(kn) mutex_lock(&rdtgroup_mutex)
cpus_read_lock() resctrl_fs_teardown()
mutex_lock(&rdtgroup_mutex) rmdir_all_sub()
mon_put_kn_priv()
/* Delete all mon_data structures */
rdtgroup_destroy_root()
kernfs_destroy_root()
rdtgroup_default.kn = NULL
mutex_unlock(&rdtgroup_mutex)
/*
* rdtgroup_default.flags is empty so
* rdtgroup_kn_lock_live() returns
* &rdtgroup_default
*/
md = of->kn->priv;
/* md points to freed mon_data */
Set RDT_DELETED for the default group unconditionally since the flag does
not lead to the freeing of this statically allocated group.
Do not allow a new resctrl mount if there are any waiters on default group
of previous mount. A new mount will re-initialize the default group that
would appear to waiters from previous mount as though the default group is
accessible causing them to access the mon_data structures from the previous
mount that have been removed.
Fixes: 2a6566038544 ("x86/resctrl: Expand the width of domid by replacing mon_data_bits")
Closes: https://sashiko.dev/#/patchset/20260508182143.14592-1-tony.luck%40intel.com?part=2 [1]
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/49a2ca3ca688f27e1a646cf90e1dc69287021127.1783377598.git.reinette.chatre@intel.com
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If mkdir_mondata_all() or a subsequent call in rdt_get_tree() fails, the
mon_data structures allocated by mon_get_kn_priv() are leaked.
Add mon_put_kn_priv() to the out_mongrp error path to free the mon_data
structures.
Fixes: 2a6566038544 ("x86/resctrl: Expand the width of domid by replacing mon_data_bits")
Closes: https://lore.kernel.org/lkml/5d38c1fb-8f91-472b-8897-24b2f50c772b@intel.com/
Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/433623b7e3316ffd52323255d1aa4f156ad97cb1.1783377598.git.reinette.chatre@intel.com
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The software controller requires that there is one MBM counter per monitor
group that is assigned to the event backing the software controller, as per
mba_MBps_event. When mbm_event mode is in use, it is not guaranteed that any
particular event will have an assigned counter.
Currently, only AMD systems support counter assignment, but the MBA delay
is non-linear and so the software controller is never supported anyway. On
MPAM systems, the MBA delay is linear and so the software controller could
be supported. The MPAM driver, unless a need arises, will not support the
'default' mbm_assign_mode and will always use the 'mbm_event' mode for
memory bandwidth monitoring.
Rather than develop a way to guarantee the counter assignment requirements
needed by the software controller, take the pragmatic approach. Don't allow
the software controller to be used at the same time as 'mbm_event' mode. As
MPAM is the only relevant architecture and it will use 'mbm_event' mode
whenever there are assignable MBM counters, for simplicity's sake, don't
allow the software controller when the MBM counters are assignable.
Implement this by failing the mount if the user requests the software
controller, the mba_MBps option, and the MBM counters are assignable.
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com
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configurable
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>/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 <ben.horgan@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/20260506082855.3694761-1-ben.horgan@arm.com
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The error path in resctrl_mkdir_event_configs() is unnecessarily
complicated. Simplify it to just return directly on error.
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20260506082855.3694761-1-ben.horgan@arm.com
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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 <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/1c50b9f7c73251c007133590986f127e1af57780.1775576382.git.reinette.chatre@intel.com
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This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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 <kees@kernel.org>
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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Clearing a monitor group's mon_data directory is complicated because of the
support for Sub-NUMA Cluster (SNC) mode.
Refactor the SNC case into a helper function to make it easier to add support
for a new telemetry resource.
Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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Population of a monitor group's mon_data directory is unreasonably complicated
because of the support for Sub-NUMA Cluster (SNC) mode.
Split out the SNC code into a helper function to make it easier to add support
for a new telemetry resource.
Move all the duplicated code to make and set owner of domain directories into
the mon_add_all_files() helper and rename to _mkdir_mondata_subdir().
Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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domains
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 <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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Enumeration of Intel telemetry events is an asynchronous process involving
several mutually dependent drivers added as auxiliary devices during the
device_initcall() phase of Linux boot. The process finishes after the probe
functions of these drivers completes. But this happens after
resctrl_arch_late_init() is executed.
Tracing the enumeration process shows that it does complete a full seven
seconds before the earliest possible mount of the resctrl file system (when
included in /etc/fstab for automatic mount by systemd).
Add a hook for use by telemetry event enumeration and initialization and
run it once at the beginning of resctrl mount without any locks held.
The architecture is responsible for any required locking.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20260105191711.GBaVwON5nZn-uO6Sqg@fat_crate.local
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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 <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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Up until now, all monitoring events were associated with the L3 resource and it
made sense to use the L3 specific "struct rdt_mon_domain *" argument to functions
operating on domains.
Telemetry events will be tied to a new resource with its instances represented
by a new domain structure that, just like struct rdt_mon_domain, starts with
the generic struct rdt_domain_hdr.
Prepare to support domains belonging to different resources by changing the
calling convention of functions operating on domains. Pass the generic header
and use that to find the domain specific structure where needed.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com
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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
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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
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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
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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
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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
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A new resource group is intended to be created with sane defaults. For a cache
resource this means all cache portions the new group could possibly allocate
into. This includes unused cache portions and shareable cache portions used by
other groups and hardware.
New resource group creation does not take sparse masks into account. After
determining the bitmask reflecting the new group's possible allocations the
bitmask is forced to be contiguous even if the system supports sparse masks.
For example, a new group could by default allocate into a large portion of
cache represented by 0xff0f, but it is instead created with a mask of 0xf.
Do not force a contiguous allocation range if the system supports sparse masks.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/abbbb008bc09d982d715e79d3b885c10f92c64e0.1763426240.git.reinette.chatre@intel.com
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Resctrl subsystem can support two monitoring modes, "mbm_event" or "default".
In mbm_event mode, monitoring event can only accumulate data while it is
backed by a hardware counter. In "default" mode, resctrl assumes there is
a hardware counter for each event within every CTRL_MON and MON group.
Introduce mbm_assign_mode resctrl file to switch between mbm_event and default
modes.
Example:
To list the MBM monitor modes supported:
$ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
[mbm_event]
default
To enable the "mbm_event" counter assignment mode:
$ echo "mbm_event" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
To enable the "default" monitoring mode:
$ echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
Reset MBM event counters automatically as part of changing the mode. Clear
both architectural and non-architectural event states to prevent overflow
conditions during the next event read. Clear assignable counter configuration
on all the domains. Also, enable auto assignment when switching to "mbm_event"
mode.
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
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The BMEC (Bandwidth Monitoring Event Configuration) feature enables per-domain
event configuration. With BMEC the MBM events are configured using the
mbm_total_bytes_config or mbm_local_bytes_config files in
/sys/fs/resctrl/info/L3_MON/
and the per-domain event configuration affects all monitor resource groups.
The mbm_event counter assignment mode enables counters to be assigned to RMID
(i.e. a monitor resource group), event pairs, with potentially unique event
configurations associated with every counter.
There may be systems that support both BMEC and mbm_event counter assignment
mode, but resctrl supporting both concurrently will present a conflicting
interface to the user with both per-domain and per RMID, event configurations
active at the same time.
The mbm_event counter assignment provides most flexibility to user space
and aligns with Arm's counter support. On systems that support both,
disable BMEC event configuration when mbm_event mode is enabled by hiding
the mbm_total_bytes_config or mbm_local_bytes_config files when mbm_event
mode is enabled. Ensure mon_features always displays accurate information
about monitor features.
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
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Enable the mbm_l3_assignments resctrl file to be used to modify counter
assignments of CTRL_MON and MON groups when the "mbm_event" counter
assignment mode is enabled.
Process the assignment modifications in the following format:
<Event>:<Domain id>=<Assignment state>;<Domain id>=<Assignment state>
Event: A valid MBM event in the
/sys/fs/resctrl/info/L3_MON/event_configs directory.
Domain ID: A valid domain ID. When writing, '*' applies the changes
to all domains.
Assignment states:
_ : Unassign a counter.
e : Assign a counter exclusively.
Examples:
$ cd /sys/fs/resctrl
$ cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=e;1=e
mbm_local_bytes:0=e;1=e
To unassign the counter associated with the mbm_total_bytes event on
domain 0:
$ echo "mbm_total_bytes:0=_" > mbm_L3_assignments
$ cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=_;1=e
mbm_local_bytes:0=e;1=e
To unassign the counter associated with the mbm_total_bytes event on
all the domains:
$ echo "mbm_total_bytes:*=_" > mbm_L3_assignments
$ cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=_;1=_
mbm_local_bytes:0=e;1=e
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
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Introduce the mbm_L3_assignments resctrl file associated with CTRL_MON and MON
resource groups to display the counter assignment states of the resource group
when "mbm_event" counter assignment mode is enabled.
Display the list in the following format:
<Event>:<Domain id>=<Assignment state>;<Domain id>=<Assignment state>
Event: A valid MBM event listed in
/sys/fs/resctrl/info/L3_MON/event_configs directory.
Domain ID: A valid domain ID.
The assignment state can be one of the following:
_ : No counter assigned.
e : Counter assigned exclusively.
Example:
To list the assignment states for the default group
$ cd /sys/fs/resctrl
$ cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=e;1=e
mbm_local_bytes:0=e;1=e
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
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Resctrl provides a user-configurable option mbm_assign_on_mkdir that
determines if a counter will automatically be assigned to an RMID, event pair
when its associated monitor group is created via mkdir.
Enable mbm_assign_on_mkdir by default to automatically assign counters to
the two default events (MBM total and MBM local) of a new monitoring group
created via mkdir. This maintains backward compatibility with original
resctrl support for these two events.
Unassign and free counters belonging to a monitoring group when the group
is deleted.
Monitor group creation does not fail if a counter cannot be assigned to one or
both events. There may be limited counters and users have the flexibility to
modify counter assignments at a later time. Log the error message "Failed to
allocate counter for <event> in domain <id>" in
/sys/fs/resctrl/info/last_cmd_status when a new monitoring group is created
but counter assignment failed.
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
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The "mbm_event" counter assignment mode allows users to assign a hardware
counter to an RMID, event pair and monitor the bandwidth as long as it is
assigned.
Introduce a user-configurable option that determines if a counter will
automatically be assigned to an RMID, event pair when its associated
monitor group is created via mkdir. Accessible when "mbm_event" counter
assignment mode is enabled.
Suggested-by: Peter Newman <peternewman@google.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
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When "mbm_event" counter assignment mode is enabled, users can modify the
event configuration by writing to the 'event_filter' resctrl file. The event
configurations for mbm_event mode are located in
/sys/fs/resctrl/info/L3_MON/event_configs/.
Update the assignments of all CTRL_MON and MON resource groups when the event
configuration is modified.
Example:
$ mount -t resctrl resctrl /sys/fs/resctrl
$ cd /sys/fs/resctrl/
$ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter
local_reads,local_non_temporal_writes,local_reads_slow_memory
$ echo "local_reads,local_non_temporal_writes" >
info/L3_MON/event_configs/mbm_total_bytes/event_filter
$ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter
local_reads,local_non_temporal_writes
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
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The "mbm_event" counter assignment mode allows the user to assign a hardware
counter to an RMID, event pair and monitor the bandwidth as long as it is
assigned. The user can specify the memory transaction(s) for the counter to
track.
When this mode is supported, the /sys/fs/resctrl/info/L3_MON/event_configs
directory contains a sub-directory for each MBM event that can be assigned to
a counter. The MBM event sub-directory contains a file named "event_filter"
that is used to view and modify which memory transactions the MBM event is
configured with.
Create /sys/fs/resctrl/info/L3_MON/event_configs directory on resctrl mount
and pre-populate it with directories for the two existing MBM events:
mbm_total_bytes and mbm_local_bytes. Create the "event_filter" file within
each MBM event directory with the needed *show() that displays the memory
transactions with which the MBM event is configured.
Example:
$ mount -t resctrl resctrl /sys/fs/resctrl
$ cd /sys/fs/resctrl/
$ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter
local_reads,remote_reads,local_non_temporal_writes,
remote_non_temporal_writes,local_reads_slow_memory,
remote_reads_slow_memory,dirty_victim_writes_all
$ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter
local_reads,local_non_temporal_writes,local_reads_slow_memory
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
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Introduce the "available_mbm_cntrs" resctrl file to display the number of
counters available for assignment in each domain when "mbm_event" mode is
enabled.
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
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The "mbm_event" counter assignment mode allows users to assign a hardware
counter to an RMID, event pair and monitor bandwidth usage as long as it is
assigned. The hardware continues to track the assigned counter until it is
explicitly unassigned by the user. Counters are assigned/unassigned at
monitoring domain level.
Manage a monitoring domain's hardware counters using a per monitoring
domain array of struct mbm_cntr_cfg that is indexed by the hardware
counter ID. A hardware counter's configuration contains the MBM event
ID and points to the monitoring group that it is assigned to, with a NULL
pointer meaning that the hardware counter is available for assignment.
There is no direct way to determine which hardware counters are assigned
to a particular monitoring group. Check every entry of every hardware
counter configuration array in every monitoring domain to query which
MBM events of a monitoring group is tracked by hardware. Such queries are
acceptable because of a very small number of assignable counters (32
to 64).
Suggested-by: Peter Newman <peternewman@google.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
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The "mbm_event" counter assignment mode allows users to assign a hardware
counter to an RMID, event pair and monitor bandwidth usage as long as it is
assigned. The hardware continues to track the assigned counter until it is
explicitly unassigned by the user.
Create 'num_mbm_cntrs' resctrl file that displays the number of counters
supported in each domain. 'num_mbm_cntrs' is only visible to user space when
the system supports "mbm_event" mode.
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
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Introduce the resctrl file "mbm_assign_mode" to list the supported counter
assignment modes.
The "mbm_event" counter assignment mode allows users to assign a hardware
counter to an RMID, event pair and monitor bandwidth usage as long as it is
assigned. The hardware continues to track the assigned counter until it is
explicitly unassigned by the user. Each event within a resctrl group can be
assigned independently in this mode.
On AMD systems "mbm_event" mode is backed by the ABMC (Assignable Bandwidth
Monitoring Counters) hardware feature and is enabled by default.
The "default" mode is the existing mode that works without the explicit
counter assignment, instead relying on dynamic counter assignment by hardware
that may result in hardware not dedicating a counter resulting in monitoring
data reads returning "Unavailable".
Provide an interface to display the monitor modes on the system.
$ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
[mbm_event]
default
Add IS_ENABLED(CONFIG_RESCTRL_ASSIGN_FIXED) check to support Arm64.
On x86, CONFIG_RESCTRL_ASSIGN_FIXED is not defined. On Arm64, it will be
defined when the "mbm_event" mode is supported.
Add IS_ENABLED(CONFIG_RESCTRL_ASSIGN_FIXED) check early to ensure the user
interface remains compatible with upcoming Arm64 support. IS_ENABLED() safely
evaluates to 0 when the configuration is not defined.
As a result, for MPAM, the display would be either:
[default]
or
[mbm_event]
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
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