linux-next.git/arch/x86/kernel/cpu/resctrl, branch master

Merge branch into tip/master: 'x86/cache'

2026-08-03T05:45:33+00:00

# New commits in x86/cache: 854db793d407 ("fs/resctrl: Inform user space when status buffer overflowed") bb38d4571964 ("fs/resctrl: Communicate resource group deleted error via last_cmd_status") b37678cfe51c ("fs/resctrl: Add last_cmd_status support for writes to max_threshold_occupancy") 242c0ab4d51d ("fs/resctrl: Change last_cmd_status custom during input parsing") 7a8c45106b68 ("fs/resctrl: Use accurate and symmetric exit flows") cc2ca4296f72 ("fs/resctrl: Pass error reading event through to user space") 6cf4970e9d02 ("fs/resctrl: Use accurate type for rdt_resource::rid") b3d683bf761d ("fs/resctrl: Change pattern used to track number of entries in enum resctrl_conf_type") 097d3f227bbd ("x86/resctrl: Protect against bad shift") f20bed0cc8da ("fs/resctrl: Use correct format specifier for printing error pointers") 2566b5cd6a27 ("fs/resctrl: Fix UAF from worker threads when domains are removed") 25afd838fb2a ("x86/resctrl: Ensure domain fully initialized before placed on RCU list") 2d77f9768850 ("fs/resctrl: Prevent deadlock and use-after-free in info file handlers") f5bcf539484d ("fs/resctrl: Prevent use-after-free in rdtgroup_kn_put()") 4f6db8caa19d ("fs/resctrl: Fix deadlock on errors during mount") 09e9ae67e622 ("fs/resctrl: Move functions to avoid forward references in subsequent fixes") 11b57be8e406 ("x86,fs/resctrl: Document safe RCU list traversal") Signed-off-by: Ingo Molnar

Merge branch 'x86/msr' into x86/merge, to aid CI testing

2026-07-28T08:08:22+00:00

Signed-off-by: Ingo Molnar

x86/resctrl: Protect against bad shift

2026-07-22T21:38:18+00:00

The size of the bandwidth field is enumerated from AMD hardware. resctrl uses this field width to determine the maximum bandwidth supported that is stored in resctrl_membw::max_bw. User space allocation requests ("control values") are compared against this maximum for validity before being programmed to hardware. resctrl filesystem and resctrl x86 architecture code only support u32 control values: resctrl_membw::max_bw is a u32, the control value provided by user space is parsed into u32 local variables, and after validity checks, the control value is staged into the u32 resctrl_staged_config::new_ctrl for architecture consumption. The resctrl x86 architecture code in turn caches the new control value into the u32 array rdt_hw_ctrl_domain::ctrl_val[]. The AMD bandwidth field to which control values are written can be up to 64 bits wide. While not an issue with current hardware (bandwidths that require more than a u32, more than 536870911.875 GB/s, seem unreasonable today), it is theoretically possible that enumeration of maximum bandwidth field width will return values that are according to specification but cannot be supported by resctrl. Static checkers complain about this size mismatch. Fix the static checker complaint by explicitly encoding the fact that resctrl is unable to support all values that the hardware specification allows. Switch to BIT() instead of open-coding the bitshift to avoid signed integer overflow if the number of bits is a valid 31. Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tony Luck Link: https://patch.msgid.link/dd9fc3505c0ed250c5f14898b0ed6d7460a3cb82.1784753375.git.reinette.chatre@intel.com

x86/resctrl: Ensure domain fully initialized before placed on RCU list

2026-07-13T20:58:30+00:00

A resctrl domain consists of the domain structure self that includes pointers to dynamically allocated filesystem as well as architecture specific data. For example, the L3 monitoring domain structure consists of the architecture specific struct rdt_hw_l3_mon_domain that contains the dynamically allocated rdt_hw_l3_mon_domain::arch_mbm_states architectural state and the embedded struct rdt_l3_mon_domain contains the dynamically allocated rdt_l3_mon_domain::mbm_states resctrl fs state. The domains are added to and removed from an RCU protected list while cpus_write_lock() is held so that readers could access domains via cpus_read_lock() or from an RCU read-side critical section. A reader accessing a domain via the RCU list expects that the domain and all its dynamically allocated data is accessible. Only place the domain on the RCU list when all its dynamically allocated data is ready, similarly unlink it from RCU list (again with cpus_write_lock() held) before removing any of its dynamically allocated data. Calling resctrl_online_mon_domain() before adding the domain to the RCU list creates the kernfs files that expose the domain's monitoring data to user space before adding the domain to the RCU list. This is safe because rdtgroup_mondata_show() acquires cpus_read_lock() before it traverses the RCU list and will thus block until the domain is added to the RCU list. There are no readers accessing a domain via RCU list. Ensure safety of access when such a reader arrives. Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tony Luck Reviewed-by: Chen Yu Link: https://patch.msgid.link/31ae67084c983e8cb8c5ef2c65e1096de5e8f9b0.1783963505.git.reinette.chatre@intel.com

x86,fs/resctrl: Document safe RCU list traversal

2026-07-13T18:35:50+00:00

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 Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/d9373f8da8ffde667740e186ffc96ab69628ac9a.1783963505.git.reinette.chatre@intel.com

x86/resctrl: Stop using 32-bit MSR interfaces

2026-07-02T09:54:52+00:00

The 32-bit MSR interfaces rdmsr() and wrmsr() are planned to be removed. Use the related 64-bit variants instead. Signed-off-by: Juergen Gross Signed-off-by: Ingo Molnar Acked-by: Reinette Chatre Link: https://patch.msgid.link/20260629060526.3638272-18-jgross@suse.com

x86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled

2026-07-01T20:15:02+00:00

The architecture updates the cpu_mask in a domain's header to track which online CPUs are associated with the domain. When this mask becomes empty the architecture initiates offline of the domain that includes calling on resctrl fs to offline the domain. If it is a monitoring domain in which LLC occupancy is tracked resctrl fs forces the limbo handler to clear all busy RMID state associated with the domain. The limbo handler always reads the current event value associated with a busy RMID irrespective of it being checked as part of regular "is it still busy" check or whether it will be forced released anyway. When reading an RMID on a system with SNC enabled the "logical RMID" is converted to the "physical RMID" and this conversion requires the NUMA node ID of the resctrl monitoring domain that is in turn determined by querying the NUMA node ID of any CPU belonging to the monitoring domain. When the monitoring domain is going offline its cpu_mask is empty causing the NUMA node ID query via cpu_to_node() to be done with "nr_cpu_ids" as argument resulting in an out-of-bounds access. Refactor the limbo handler to skip reading the RMID when the RMID will just be forced to no longer be dirty in the domain anyway. Add a safety check to the architecture's RMID reader to protect against this scenario. Fixes: e13db55b5a0d ("x86/resctrl: Introduce snc_nodes_per_l3_cache") Closes: https://sashiko.dev/#/patchset/cover.1780456704.git.reinette.chatre%40intel.com?part=9 Reported-by: Sashiko Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov (AMD) Cc: Link: https://patch.msgid.link/16137433df42f85013b2f7a53626795cbd6637b9.1781029125.git.reinette.chatre@intel.com

Merge tag 'x86_cache_for_v7.2_rc1' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

2026-06-16T00:05:40+00:00

Pull x86 resource control updates from Borislav Petkov: "Preparatory work for MPAM counter assignment: - Simplify the error handling path when creating monitor group event configuration directories - Make the MBM event filter configurable only on architectures that support it and expose this with the respective file modes in the event config - Disallow the MBA software controller on systems where MBM counters are assignable, as it requires continuous bandwidth measurement that assignable counters do not guarantee - Replace a compile-time Kconfig option for fixed counter assignment with a per-architecture runtime property, and expose whether the counter assignment mode is changeable to userspace - Continue counter allocation across all domains instead of aborting at the first failure - Document that automatic MBM counter assignment is best effort and may not assign counters to all domains - Document the behavior of task ID 0 and idle tasks in the resctrl tasks file" * tag 'x86_cache_for_v7.2_rc1' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: fs/resctrl: Document tasks file behaviour for task id 0 and idle tasks fs/resctrl: Document that automatic counter assignment is best effort fs/resctrl: Continue counter allocation after failure fs/resctrl: Add monitor property 'mbm_cntr_assign_fixed' fs/resctrl: Disallow the software controller when MBM counters are assignable x86,fs/resctrl: Create 'event_filter' files read only if they're not configurable fs/resctrl: Tidy up the error path in resctrl_mkdir_event_configs()

Merge tag 'x86-cpu-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

2026-06-15T09:55:17+00:00

Pull x86 cpuid updates from Ingo Molnar: - CPUID API updates (Ahmed S. Darwish): - Introduce a centralized CPUID parser - Introduce a centralized CPUID data model - Introduce - Rename cpuid_leaf()/cpuid_subleaf() APIs - treewide: Explicitly include the x86 CPUID headers - Update to x86-cpuid-db v3.1 (Maciej Wieczor-Retman) - Continued removal of pre-i586 support and related simplifications (Ingo Molnar) - Add Intel CPU model number for rugged Panther Lake (Tony Luck) - Misc fixes, updates and cleanups by Arnd Bergmann, Chao Gao, Lukas Bulwahn, Sohil Mehta, Maciej Wieczor-Retman. * tag 'x86-cpu-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (25 commits) x86/cpu: Make CONFIG_X86_CX8 unconditional x86/cpu: Remove unused !CONFIG_X86_TSC code x86/cpuid: Update bitfields to x86-cpuid-db v3.1 tools/x86/kcpuid: Update bitfields to x86-cpuid-db v3.1 x86/cpu: Make CONFIG_X86_TSC unconditional MAINTAINERS: Drop obsolete FPU EMULATOR section x86/cpu: Fix a F00F bug warning and clean up surrounding code x86/cpu: Add Intel CPU model number for rugged Panther Lake x86/cpuid: Introduce a centralized CPUID parser x86/cpu: Introduce a centralized CPUID data model x86/cpuid: Introduce x86/cpuid: Rename cpuid_leaf()/cpuid_subleaf() APIs x86/cpu: Do not include the CPUID API header in asm/processor.h Documentation: core-api/cpu_hotplug: Remove stale cpu0_hotplug docs x86/cpu, cpufreq: Remove AMD ELAN support x86/fpu: Remove the math-emu/ FPU emulation library x86/fpu: Remove the 'no387' boot option x86/fpu: Remove MATH_EMULATION and related glue code treewide: Explicitly include the x86 CPUID headers x86/cpu: Remove the CONFIG_X86_INVD_BUG quirk ...

Merge tag 'x86-msr-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

2026-06-15T09:38:14+00:00

Pull x86/msr updates from Ingo Molnar: - Large series to reorganize the rdmsr/wrmsr APIs to remove 32-bit variants and convert to 64-bit variants (Juergen Gross) - Fix W=1 warning (HyeongJun An) * tag 'x86-msr-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: x86/msr: Remove wrmsrl() x86/msr: Switch wrmsrl() users to wrmsrq() x86/msr: Remove rdmsrl() x86/msr: Switch rdmsrl() users to rdmsrq() x86/msr: Remove wrmsr_safe_on_cpu() x86/msr: Switch wrmsr_safe_on_cpu() users to wrmsrq_safe_on_cpu() x86/msr: Remove rdmsr_safe_on_cpu() x86/msr: Switch rdmsr_safe_on_cpu() users to rdmsrq_safe_on_cpu() x86/msr: Don't use rdmsr_safe_on_cpu() in rdmsrq_safe_on_cpu() x86/msr: Remove wrmsr_on_cpu() x86/msr: Switch wrmsr_on_cpu() users to wrmsrq_on_cpu() x86/msr: Remove rdmsr_on_cpu() x86/msr: Switch rdmsr_on_cpu() users to rdmsrq_on_cpu() x86/msr: Remove rdmsrl_on_cpu() x86/msr: Switch rdmsrl_on_cpu() user to rdmsrq_on_cpu() x86/process: Convert rdmsr() to rdmsrq() in arch_post_acpi_subsys_init() to address W=1 warning