kernel.git/arch/x86/kernel/cpu/resctrl/rdtgroup.c, branch linux-6.15.y

x86/resctrl: Fix rdtgroup_mkdir()'s unlocked use of kernfs_node::name

2025-04-09T09:35:08Z

Since 741c10b096bc ("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: | | 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: 741c10b096bc ("kernfs: Use RCU to access kernfs_node::name.") Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Acked-by: Ingo Molnar Link: https://lore.kernel.org/r/20250407124637.2433230-1-james.morse@arm.com

Merge tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2025-04-01T18:02:03Z

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' ...

x86/resctrl: Move get_{mon,ctrl}_domain_from_cpu() to live with their callers

2025-03-12T11:24:58Z

Each of get_{mon,ctrl}_domain_from_cpu() only has one caller. Once the filesystem code is moved to /fs/, there is no equivalent to core.c. Move these functions to each live next to their caller. This allows them to be made static and the header file entries to be removed. Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Fenghua Yu Reviewed-by: Reinette Chatre Reviewed-by: Babu Moger Reviewed-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Shaopeng Tan Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-31-james.morse@arm.com

x86/resctrl: Handle throttle_mode for SMBA resources

2025-03-12T11:24:46Z

Now that the visibility of throttle_mode is being managed by resctrl, it should consider resources other than MBA that may have a throttle_mode. SMBA is one such resource. Extend thread_throttle_mode_init() to check SMBA for a throttle_mode. Adding support for multiple resources means it is possible for a platform with both MBA and SMBA, but an undefined throttle_mode on one of them to make the file visible. Add the 'undefined' case to rdt_thread_throttle_mode_show(). Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Reviewed-by: Babu Moger Reviewed-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Shaopeng Tan Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-29-james.morse@arm.com

x86/resctrl: Move RFTYPE flags to be managed by resctrl

2025-03-12T11:24:37Z

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 Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Reviewed-by: Babu Moger Reviewed-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Shaopeng Tan Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-28-james.morse@arm.com

x86/resctrl: Allow an architecture to disable pseudo lock

2025-03-12T11:24:25Z

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 Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Shaopeng Tan Reviewed-by: Tony Luck Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Reviewed-by: Babu Moger Tested-by: Carl Worth # arm64 Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-25-james.morse@arm.com

x86/resctrl: Move mbm_cfg_mask to struct rdt_resource

2025-03-12T11:24:09Z

The mbm_cfg_mask field lists the bits that user-space can set when configuring an event. This value is output via the last_cmd_status file. Once the filesystem parts of resctrl are moved to live in /fs/, the struct rdt_hw_resource is inaccessible to the filesystem code. Because this value is output to user-space, it has to be accessible to the filesystem code. Move it to struct rdt_resource. Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Shaopeng Tan Reviewed-by: Tony Luck Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Reviewed-by: Babu Moger Tested-by: Carl Worth # arm64 Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-23-james.morse@arm.com

x86/resctrl: Change mon_event_config_{read,write}() to be arch helpers

2025-03-12T11:23:49Z

mon_event_config_{read,write}() are called via IPI and access model specific registers to do their work. To support another architecture, this needs abstracting. Rename mon_event_config_{read,write}() to have a "resctrl_arch_" prefix, and move their struct mon_config_info parameter into . This allows another architecture to supply an implementation of these. As struct mon_config_info is now exposed globally, give it a 'resctrl_' prefix. MPAM systems need access to the domain to do this work, add the resource and domain to struct resctrl_mon_config_info. Co-developed-by: Dave Martin Signed-off-by: Dave Martin Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Shaopeng Tan Reviewed-by: Tony Luck Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Reviewed-by: Babu Moger Tested-by: Carl Worth # arm64 Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-21-james.morse@arm.com

x86/resctrl: Move the is_mbm_*_enabled() helpers to asm/resctrl.h

2025-03-12T11:23:33Z

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 Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tony Luck Reviewed-by: Fenghua Yu Reviewed-by: Reinette Chatre Reviewed-by: Babu Moger Reviewed-by: Shaopeng Tan Tested-by: Carl Worth # arm64 Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-19-james.morse@arm.com

x86/resctrl: Move monitor init work to a resctrl init call

2025-03-12T11:23:21Z

rdt_get_mon_l3_config() is called from the arch's resctrl_arch_late_init(), and initialises both architecture specific fields, such as hw_res->mon_scale and resctrl filesystem fields by calling dom_data_init(). To separate the filesystem and architecture parts of resctrl, this function needs splitting up. Add resctrl_mon_resource_init() to do the filesystem specific work, and call it from resctrl_init(). This runs later, but is still before the filesystem is mounted and the rmid_ptrs[] array can be used. [ bp: Massage commit message. ] Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Shaopeng Tan Reviewed-by: Tony Luck Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Reviewed-by: Babu Moger Tested-by: Carl Worth # arm64 Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Amit Singh Tomar # arm64 Tested-by: Shanker Donthineni # arm64 Tested-by: Babu Moger Link: https://lore.kernel.org/r/20250311183715.16445-17-james.morse@arm.com