Since
741c10b096 ("kernfs: Use RCU to access kernfs_node::name.")
a helper rdt_kn_name() that checks that rdtgroup_mutex is held has been used
for all accesses to the kernfs node name.
rdtgroup_mkdir() uses the name to determine if a valid monitor group is being
created by checking the parent name is "mon_groups". This is done without
holding rdtgroup_mutex, and now triggers the following warning:
| WARNING: suspicious RCU usage
| 6.15.0-rc1 #4465 Tainted: G E
| -----------------------------
| arch/x86/kernel/cpu/resctrl/internal.h:408 suspicious rcu_dereference_check() usage!
[...]
| Call Trace:
| <TASK>
| dump_stack_lvl
| lockdep_rcu_suspicious.cold
| is_mon_groups
| rdtgroup_mkdir
| kernfs_iop_mkdir
| vfs_mkdir
| do_mkdirat
| __x64_sys_mkdir
| do_syscall_64
| entry_SYSCALL_64_after_hwframe
Creating a control or monitor group calls mkdir_rdt_prepare(), which uses
rdtgroup_kn_lock_live() to take the rdtgroup_mutex.
To avoid taking and dropping the lock, move the check for the monitor group
name and position into mkdir_rdt_prepare() so that it occurs under
rdtgroup_mutex. Hoist is_mon_groups() earlier in the file.
[ bp: Massage. ]
Fixes: 741c10b096 ("kernfs: Use RCU to access kernfs_node::name.")
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250407124637.2433230-1-james.morse@arm.com
Pull driver core updatesk from Greg KH:
"Here is the big set of driver core updates for 6.15-rc1. Lots of stuff
happened this development cycle, including:
- kernfs scaling changes to make it even faster thanks to rcu
- bin_attribute constify work in many subsystems
- faux bus minor tweaks for the rust bindings
- rust binding updates for driver core, pci, and platform busses,
making more functionaliy available to rust drivers. These are all
due to people actually trying to use the bindings that were in
6.14.
- make Rafael and Danilo full co-maintainers of the driver core
codebase
- other minor fixes and updates"
* tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (52 commits)
rust: platform: require Send for Driver trait implementers
rust: pci: require Send for Driver trait implementers
rust: platform: impl Send + Sync for platform::Device
rust: pci: impl Send + Sync for pci::Device
rust: platform: fix unrestricted &mut platform::Device
rust: pci: fix unrestricted &mut pci::Device
rust: device: implement device context marker
rust: pci: use to_result() in enable_device_mem()
MAINTAINERS: driver core: mark Rafael and Danilo as co-maintainers
rust/kernel/faux: mark Registration methods inline
driver core: faux: only create the device if probe() succeeds
rust/faux: Add missing parent argument to Registration::new()
rust/faux: Drop #[repr(transparent)] from faux::Registration
rust: io: fix devres test with new io accessor functions
rust: io: rename `io::Io` accessors
kernfs: Move dput() outside of the RCU section.
efi: rci2: mark bin_attribute as __ro_after_init
rapidio: constify 'struct bin_attribute'
firmware: qemu_fw_cfg: constify 'struct bin_attribute'
powerpc/perf/hv-24x7: Constify 'struct bin_attribute'
...
resctrl_file_fflags_init() is called from the architecture specific code to
make the 'thread_throttle_mode' file visible. The architecture specific code
has already set the membw.throttle_mode in the rdt_resource.
This forces the RFTYPE flags used by resctrl to be exposed to the architecture
specific code.
This doesn't need to be specific to the architecture, the throttle_mode can be
used by resctrl to determine if the 'thread_throttle_mode' file should be
visible. This allows the RFTYPE flags to be private to resctrl.
Add thread_throttle_mode_init(), and use it to call resctrl_file_fflags_init()
from resctrl_init(). This avoids publishing an extra function between the
architecture and filesystem code.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-28-james.morse@arm.com
Pseudo-lock relies on knowledge of the micro-architecture to disable
prefetchers etc.
On arm64 these controls are typically secure only, meaning Linux can't access
them. Arm's cache-lockdown feature works in a very different way. Resctrl's
pseudo-lock isn't going to be used on arm64 platforms.
Add a Kconfig symbol that can be selected by the architecture. This enables or
disables building of the pseudo_lock.c file, and replaces the functions with
stubs. An additional IS_ENABLED() check is needed in rdtgroup_mode_write() so
that attempting to enable pseudo-lock reports an "Unknown or unsupported mode"
to user-space via the last_cmd_status file.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-25-james.morse@arm.com
The architecture specific parts of resctrl provide helpers like
is_mbm_total_enabled() and is_mbm_local_enabled() to hide accesses to the
rdt_mon_features bitmap.
Exposing a group of helpers between the architecture and filesystem code is
preferable to a single unsigned-long like rdt_mon_features. Helpers can be more
readable and have a well defined behaviour, while allowing architectures to hide
more complex behaviour.
Once the filesystem parts of resctrl are moved, these existing helpers can no
longer live in internal.h. Move them to include/linux/resctrl.h Once these are
exposed to the wider kernel, they should have a 'resctrl_arch_' prefix, to fit
the rest of the arch<->fs interface.
Move and rename the helpers that touch rdt_mon_features directly. is_mbm_event()
and is_mbm_enabled() are only called from rdtgroup.c, so can be moved into that
file.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-19-james.morse@arm.com
rdtgroup_rmdir_ctrl() and rdtgroup_rmdir_mon() set the per-CPU pqr_state for
CPUs that were part of the rmdir()'d group.
Another architecture might not have a 'pqr_state', its hardware may need the
values in a different format. MPAM's equivalent of RMID values are not unique,
and always need the CLOSID to be provided too.
There is only one caller that modifies a single value, (rdtgroup_rmdir_mon()).
MPAM always needs both CLOSID and RMID for the hardware value as these are
written to the same system register.
As rdtgroup_rmdir_mon() has the CLOSID on hand, only provide a helper to set
both values. These values are read by __resctrl_sched_in(), but may be written
by a different CPU without any locking, add READ/WRTE_ONCE() to avoid torn
values.
Co-developed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-10-james.morse@arm.com
The resctrl architecture code provides a data_width for the controls of each
resource. This is used to zero pad all control values in the schemata file so
they appear in columns. The same is done with the resource names to complete
the visual effect. e.g.
| SMBA:0=2048
| L3:0=00ff
AMD platforms discover their maximum bandwidth for the MB resource from
firmware, but hard-code the data_width to 4. If the maximum bandwidth requires
more digits - the tabular format is silently broken. This is also broken when
the mba_MBps mount option is used as the field width isn't updated. If new
schema are added resctrl will need to be able to determine the maximum width.
The benefit of this pretty-printing is questionable.
Instead of handling runtime discovery of the data_width for AMD platforms,
remove the feature. These fields are always zero padded so should be harmless
to remove if the whole field has been treated as a number. In the above
example, this would now look like this:
| SMBA:0=2048
| L3:0=ff
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-7-james.morse@arm.com
Resctrl occasionally wants to know something about a specific resource, in
these cases it reaches into the arch code's rdt_resources_all[] array.
Once the filesystem parts of resctrl are moved to /fs/, this means it will
need visibility of the architecture specific struct rdt_hw_resource
definition, and the array of all resources. All architectures would also need
a r_resctrl member in this struct.
Instead, abstract this via a helper to allow architectures to do different
things here. Move the level enum to the resctrl header and add a helper to
retrieve the struct rdt_resource by 'rid'.
resctrl_arch_get_resource() should not return NULL for any value in the enum,
it may instead return a dummy resource that is !alloc_enabled && !mon_enabled.
Co-developed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-3-james.morse@arm.com
Commit
6eac36bb9e ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid")
added logic that causes resctrl to search for the CLOSID with the fewest dirty
cache lines when creating a new control group, if requested by the arch code.
This depends on the values read from the llc_occupancy counters. The logic is
applicable to architectures where the CLOSID effectively forms part of the
monitoring identifier and so do not allow complete freedom to choose an unused
monitoring identifier for a given CLOSID.
This support missed that some platforms may not have these counters. This
causes a NULL pointer dereference when creating a new control group as the
array was not allocated by dom_data_init().
As this feature isn't necessary on platforms that don't have cache occupancy
monitors, add this to the check that occurs when a new control group is
allocated.
Fixes: 6eac36bb9e ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid")
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-2-james.morse@arm.com
Using RCU lifetime rules to access kernfs_node::name can avoid the
trouble with kernfs_rename_lock in kernfs_name() and kernfs_path_from_node()
if the fs was created with KERNFS_ROOT_INVARIANT_PARENT. This is usefull
as it allows to implement kernfs_path_from_node() only with RCU
protection and avoiding kernfs_rename_lock. The lock is only required if
the __parent node can be changed and the function requires an unchanged
hierarchy while it iterates from the node to its parent.
The change is needed to allow the lookup of the node's path
(kernfs_path_from_node()) from context which runs always with disabled
preemption and or interrutps even on PREEMPT_RT. The problem is that
kernfs_rename_lock becomes a sleeping lock on PREEMPT_RT.
I went through all ::name users and added the required access for the lookup
with a few extensions:
- rdtgroup_pseudo_lock_create() drops all locks and then uses the name
later on. resctrl supports rename with different parents. Here I made
a temporal copy of the name while it is used outside of the lock.
- kernfs_rename_ns() accepts NULL as new_parent. This simplifies
sysfs_move_dir_ns() where it can set NULL in order to reuse the current
name.
- kernfs_rename_ns() is only using kernfs_rename_lock if the parents are
different. All users use either kernfs_rwsem (for stable path view) or
just RCU for the lookup. The ::name uses always RCU free.
Use RCU lifetime guarantees to access kernfs_node::name.
Suggested-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Reported-by: syzbot+6ea37e2e6ffccf41a7e6@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/67251dc6.050a0220.529b6.015e.GAE@google.com/
Reported-by: Hillf Danton <hdanton@sina.com>
Closes: https://lore.kernel.org/20241102001224.2789-1-hdanton@sina.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20250213145023.2820193-7-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs_rename_lock is used to obtain stable kernfs_node::{name|parent}
pointer. This is a preparation to access kernfs_node::parent under RCU
and ensure that the pointer remains stable under the RCU lifetime
guarantees.
For a complete path, as it is done in kernfs_path_from_node(), the
kernfs_rename_lock is still required in order to obtain a stable parent
relationship while computing the relevant node depth. This must not
change while the nodes are inspected in order to build the path.
If the kernfs user never moves the nodes (changes the parent) then the
kernfs_rename_lock is not required and the RCU guarantees are
sufficient. This "restriction" can be set with
KERNFS_ROOT_INVARIANT_PARENT. Otherwise the lock is required.
Rename kernfs_node::parent to kernfs_node::__parent to denote the RCU
access and use RCU accessor while accessing the node.
Make cgroup use KERNFS_ROOT_INVARIANT_PARENT since the parent here can
not change.
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20250213145023.2820193-6-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The "mba_MBps" mount option provides an alternate method to control memory
bandwidth. Instead of specifying allowable bandwidth as a percentage of
maximum possible, the user provides a MiB/s limit value.
There is a file in each CTRL_MON group directory that shows the event
currently in use.
Allow writing that file to choose a different event.
A user can choose any of the memory bandwidth monitoring events listed in
/sys/fs/resctrl/info/L3_mon/mon_features independently for each CTRL_MON group
by writing to each of the "mba_MBps_event" files.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20241206163148.83828-8-tony.luck@intel.com
The "mba_MBps" mount option provides an alternate method to control memory
bandwidth. Instead of specifying allowable bandwidth as a percentage of
maximum possible, the user provides a MiB/s limit value.
In preparation to allow the user to pick the memory bandwidth monitoring event
used as input to the feedback loop, provide a file in each CTRL_MON group
directory that shows the event currently in use. Note that this file is only
visible when the "mba_MBps" mount option is in use.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20241206163148.83828-7-tony.luck@intel.com
The default input measurement to the mba_sc feedback loop for memory bandwidth
control when the user mounts with the "mba_MBps" option is the local bandwidth
event. But some systems may not support a local bandwidth event.
When local bandwidth event is not supported, check for support of total
bandwidth and use that instead.
Relax the mount option check to allow use of the "mba_MBps" option for systems
when only total bandwidth monitoring is supported. Also update the error
message.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20241206163148.83828-6-tony.luck@intel.com
Resctrl uses local memory bandwidth event as input to the feedback loop when
the mba_MBps mount option is used. This means that this mount option cannot be
used on systems that only support monitoring of total bandwidth.
Prepare to allow users to choose the input event independently for each
CTRL_MON group by adding a global variable "mba_mbps_default_event" used to
set the default event for each CTRL_MON group, and a new field
"mba_mbps_event" in struct rdtgroup to track which event is used for each
CTRL_MON group.
Notes:
1) Both of these are only used when the user mounts the filesystem with the
"mba_MBps" option.
2) Only check for support of local bandwidth event when initializing
mba_mbps_default_event. Support for total bandwidth event can be added
after other routines in resctrl have been updated to handle total bandwidth
event.
[ bp: Move mba_mbps_default_event extern into the arch header. ]
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20241206163148.83828-3-tony.luck@intel.com
thread_throttle_mode_init() and mbm_config_rftype_init() both initialize
fflags for resctrl files.
Adding new files will involve adding another function to initialize
the fflags. This can be simplified by adding a new function
resctrl_file_fflags_init() and passing the file name and flags
to be initialized.
Consolidate fflags initialization into resctrl_file_fflags_init() and
remove thread_throttle_mode_init() and mbm_config_rftype_init().
[ Tony: Drop __init attribute so resctrl_file_fflags_init() can be used at
run time. ]
Signed-off-by: Babu Moger <babu.moger@amd.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/r/20241206163148.83828-2-tony.luck@intel.com
'mon_info' is already zeroed in the list_for_each_entry() loop below. There
is no need to explicitly initialize it here. It just wastes some space and
cycles.
Remove this un-needed code.
On a x86_64, with allmodconfig:
Before:
======
text data bss dec hex filename
74967 5103 1880 81950 1401e arch/x86/kernel/cpu/resctrl/rdtgroup.o
After:
=====
text data bss dec hex filename
74903 5103 1880 81886 13fde arch/x86/kernel/cpu/resctrl/rdtgroup.o
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/b2ebc809c8b6c6440d17b12ccf7c2d29aaafd488.1720868538.git.christophe.jaillet@wanadoo.fr
mon_event_read() fills out most fields of the struct rmid_read that is passed
via an smp_call*() function to a CPU that is part of the correct domain to
read the monitor counters.
With Sub-NUMA Cluster (SNC) mode there are now two cases to handle:
1) Reading a file that returns a value for a single domain.
+ Choose the CPU to execute from the domain cpu_mask
2) Reading a file that must sum across domains sharing an L3 cache
instance.
+ Indicate to called code that a sum is needed by passing a NULL
rdt_mon_domain pointer.
+ Choose the CPU from the L3 shared_cpu_map.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-16-tony.luck@intel.com
In SNC mode, there are multiple subdirectories in each L3 level monitor
directory (one for each SNC node). If all the CPUs in an SNC node are taken
offline, just remove the SNC directory for that node. In non-SNC mode, or when
the last SNC node directory is removed, remove the L3 monitor directory.
Add a helper function to avoid duplicated code.
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/r/20240702173820.90368-2-tony.luck@intel.com
When SNC mode is enabled, create subdirectories and files to monitor at the SNC
node granularity. Legacy behavior is preserved by tagging the monitor files at
the L3 granularity with the "sum" attribute. When the user reads these files
the kernel will read monitor data from all SNC nodes that share the same L3
cache instance and return the aggregated value to the user.
Note that the "domid" field for files that must sum across SNC domains has the
L3 cache instance id, while non-summing files use the domain id.
The "sum" files do not need to make a call to mon_event_read() to initialize
the MBM counters. This will be handled by initializing the individual SNC nodes
that share the L3.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-14-tony.luck@intel.com
In Sub-NUMA Cluster (SNC) mode Linux must create the monitor
files in the original "mon_L3_XX" directories and also in each
of the "mon_sub_L3_YY" directories.
Refactor mkdir_mondata_subdir() to move the creation of monitoring files
into a helper function to avoid the need to duplicate code later.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-12-tony.luck@intel.com
New semantics rely on some struct rmid_read members having NULL values to
distinguish between the SNC and non-SNC scenarios. resctrl can thus no longer
rely on this struct not being initialized properly.
Initialize all on-stack declarations of struct rmid_read:
rdtgroup_mondata_show()
mbm_update()
mkdir_mondata_subdir()
to ensure that garbage values from the stack are not passed down to other
functions.
[ bp: Massage commit message. ]
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-11-tony.luck@intel.com
When SNC is enabled, monitoring data is collected at the SNC node granularity,
but must be reported at L3-cache granularity for backwards compatibility in
addition to reporting at the node level.
Add a "ci" field to the rdt_mon_domain structure to save the cache information
about the enclosing L3 cache for the domain. This provides:
1) The cache id which is needed to compose the name of the legacy monitoring
directory, and to determine which domains should be summed to provide
L3-scoped data.
2) The shared_cpu_map which is needed to determine which CPUs can be used to
read the RMID counters with the MSR interface.
This is the first step to an eventual goal of monitor reporting files like this
(for a system with two SNC nodes per L3):
$ cd /sys/fs/resctrl/mon_data
$ tree mon_L3_00
mon_L3_00 <- 00 here is L3 cache id
├── llc_occupancy \ These files provide legacy support
├── mbm_local_bytes > for non-SNC aware monitor apps
├── mbm_total_bytes / that expect data at L3 cache level
├── mon_sub_L3_00 <- 00 here is SNC node id
│ ├── llc_occupancy \ These files are finer grained
│ ├── mbm_local_bytes > data from each SNC node
│ └── mbm_total_bytes /
└── mon_sub_L3_01
├── llc_occupancy \
├── mbm_local_bytes > As above, but for node 1.
└── mbm_total_bytes /
[ bp: Massage commit message. ]
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-9-tony.luck@intel.com
When SNC is enabled there is a mismatch between the MBA control function
which operates at L3 cache scope and the MBM monitor functions which
measure memory bandwidth on each SNC node.
Block use of the mba_MBps when scopes for MBA/MBM do not match.
Improve user diagnostics by adding invalfc() message when mba_MBps
is not supported.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-8-tony.luck@intel.com
The same rdt_domain structure is used for both control and monitor
functions. But this results in wasted memory as some of the fields are
only used by control functions, while most are only used for monitor
functions.
Split into separate rdt_ctrl_domain and rdt_mon_domain structures with
just the fields required for control and monitoring respectively.
Similar split of the rdt_hw_domain structure into rdt_hw_ctrl_domain
and rdt_hw_mon_domain.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-5-tony.luck@intel.com
Resctrl assumes that control and monitor operations on a resource are
performed at the same scope.
Prepare for systems that use different scope (specifically Intel needs
to split the RDT_RESOURCE_L3 resource to use L3 scope for cache control
and NODE scope for cache occupancy and memory bandwidth monitoring).
Create separate domain lists for control and monitor operations.
Note that errors during initialization of either control or monitor
functions on a domain would previously result in that domain being
excluded from both control and monitor operations. Now the domains are
allocated independently it is no longer required to disable both control
and monitor operations if either fail.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-4-tony.luck@intel.com
The rdt_domain structure is used for both control and monitor features.
It is about to be split into separate structures for these two usages
because the scope for control and monitoring features for a resource
will be different for future resources.
To allow for common code that scans a list of domains looking for a
specific domain id, move all the common fields ("list", "id", "cpu_mask")
into their own structure within the rdt_domain structure.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-3-tony.luck@intel.com
Resctrl resources operate on subsets of CPUs in the system with the
defining attribute of each subset being an instance of a particular
level of cache. E.g. all CPUs sharing an L3 cache would be part of the
same domain.
In preparation for features that are scoped at the NUMA node level,
change the code from explicit references to "cache_level" to a more
generic scope. At this point the only options for this scope are groups
of CPUs that share an L2 cache or L3 cache.
Clean up the error handling when looking up domains. Report invalid ids
before calling rdt_find_domain() in preparation for better messages when
scope can be other than cache scope. This means that rdt_find_domain()
will never return an error. So remove checks for error from the call sites.
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>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20240628215619.76401-2-tony.luck@intel.com
reset_all_ctrls() and resctrl_arch_update_domains() use on_each_cpu_mask()
to call rdt_ctrl_update() on potentially one CPU from each domain.
But this means rdt_ctrl_update() needs to figure out which domain to
apply changes to. Doing so requires a search of all domains in a resource,
which can only be done safely if cpus_lock is held. Both callers do hold
this lock, but there isn't a way for a function called on another CPU
via IPI to verify this.
Commit
c0d848fcb0 ("x86/resctrl: Remove lockdep annotation that triggers
false positive")
removed the incorrect assertions.
Add the target domain to the msr_param structure and call
rdt_ctrl_update() for each domain separately using
smp_call_function_single(). This means that rdt_ctrl_update() doesn't
need to search for the domain and get_domain_from_cpu() can safely
assert that the cpus_lock is held since the remaining callers do not use
IPI.
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>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://lore.kernel.org/r/20240308213846.77075-2-tony.luck@intel.com
resctrl has one mutex that is taken by the architecture-specific code, and the
filesystem parts. The two interact via cpuhp, where the architecture code
updates the domain list. Filesystem handlers that walk the domains list should
not run concurrently with the cpuhp callback modifying the list.
Exposing a lock from the filesystem code means the interface is not cleanly
defined, and creates the possibility of cross-architecture lock ordering
headaches. The interaction only exists so that certain filesystem paths are
serialised against CPU hotplug. The CPU hotplug code already has a mechanism to
do this using cpus_read_lock().
MPAM's monitors have an overflow interrupt, so it needs to be possible to walk
the domains list in irq context. RCU is ideal for this, but some paths need to
be able to sleep to allocate memory.
Because resctrl_{on,off}line_cpu() take the rdtgroup_mutex as part of a cpuhp
callback, cpus_read_lock() must always be taken first.
rdtgroup_schemata_write() already does this.
Most of the filesystem code's domain list walkers are currently protected by
the rdtgroup_mutex taken in rdtgroup_kn_lock_live(). The exceptions are
rdt_bit_usage_show() and the mon_config helpers which take the lock directly.
Make the domain list protected by RCU. An architecture-specific lock prevents
concurrent writers. rdt_bit_usage_show() could walk the domain list using RCU,
but to keep all the filesystem operations the same, this is changed to call
cpus_read_lock(). The mon_config helpers send multiple IPIs, take the
cpus_read_lock() in these cases.
The other filesystem list walkers need to be able to sleep. Add
cpus_read_lock() to rdtgroup_kn_lock_live() so that the cpuhp callbacks can't
be invoked when file system operations are occurring.
Add lockdep_assert_cpus_held() in the cases where the rdtgroup_kn_lock_live()
call isn't obvious.
Resctrl's domain online/offline calls now need to take the rdtgroup_mutex
themselves.
[ bp: Fold in a build fix: https://lore.kernel.org/r/87zfvwieli.ffs@tglx ]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-25-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
When a CPU is taken offline the resctrl filesystem code needs to check if it
was the CPU nominated to perform the periodic overflow and limbo work. If so,
another CPU needs to be chosen to do this work.
This is currently done in core.c, mixed in with the code that removes the CPU
from the domain's mask, and potentially free()s the domain.
Move the migration of the overflow and limbo helpers into the filesystem code,
into resctrl_offline_cpu(). As resctrl_offline_cpu() runs before the
architecture code has removed the CPU from the domain mask, the callers need to
be told which CPU is being removed, to avoid picking it as the new CPU. This
uses the exclude_cpu feature previously added.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-24-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
The resctrl architecture specific code may need to free a domain when a CPU
goes offline, it also needs to reset the CPUs PQR_ASSOC register. Amongst
other things, the resctrl filesystem code needs to clear this CPU from the
cpu_mask of any control and monitor groups.
Currently, this is all done in core.c and called from resctrl_offline_cpu(),
making the split between architecture and filesystem code unclear.
Move the filesystem work to remove the CPU from the control and monitor groups
into a filesystem helper called resctrl_offline_cpu(), and rename the one in
core.c resctrl_arch_offline_cpu().
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-23-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
The resctrl architecture specific code may need to create a domain when a CPU
comes online, it also needs to reset the CPUs PQR_ASSOC register. The resctrl
filesystem code needs to update the rdtgroup_default CPU mask when CPUs are
brought online.
Currently, this is all done in one function, resctrl_online_cpu(). It will
need to be split into architecture and filesystem parts before resctrl can be
moved to /fs/.
Pull the rdtgroup_default update work out as a filesystem specific cpu_online
helper. resctrl_online_cpu() is the obvious name for this, which means the
version in core.c needs renaming.
resctrl_online_cpu() is called by the arch code once it has done the work to
add the new CPU to any domains.
In future patches, resctrl_online_cpu() will take the rdtgroup_mutex itself.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-21-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
resctrl reads rdt_alloc_capable or rdt_mon_capable to determine whether any of
the resources support the corresponding features. resctrl also uses the
static keys that affect the architecture's context-switch code to determine the
same thing.
This forces another architecture to have the same static keys.
As the static key is enabled based on the capable flag, and none of the
filesystem uses of these are in the scheduler path, move the capable flags
behind helpers, and use these in the filesystem code instead of the static key.
After this change, only the architecture code manages and uses the static keys
to ensure __resctrl_sched_in() does not need runtime checks.
This avoids multiple architectures having to define the same static keys.
Cases where the static key implicitly tested if the resctrl filesystem was
mounted all have an explicit check now.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-20-james.morse@arm.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
