linux/fs/resctrl/ctrlmondata.c, branch v6.16

x86,fs/resctrl: Remove inappropriate references to cacheinfo in the resctrl subsystem

2025-06-16T19:06:12Z

In the resctrl subsystem's Sub-NUMA Cluster (SNC) mode, the rdt_mon_domain structure representing a NUMA node relies on the cacheinfo interface (rdt_mon_domain::ci) to store L3 cache information (e.g., shared_cpu_map) for monitoring. The L3 cache information of a SNC NUMA node determines which domains are summed for the "top level" L3-scoped events. rdt_mon_domain::ci is initialized using the first online CPU of a NUMA node. When this CPU goes offline, its shared_cpu_map is cleared to contain only the offline CPU itself. Subsequently, attempting to read counters via smp_call_on_cpu(offline_cpu) fails (and error ignored), returning zero values for "top-level events" without any error indication. Replace the cacheinfo references in struct rdt_mon_domain and struct rmid_read with the cacheinfo ID (a unique identifier for the L3 cache). rdt_domain_hdr::cpu_mask contains the online CPUs associated with that domain. When reading "top-level events", select a CPU from rdt_domain_hdr::cpu_mask and utilize its L3 shared_cpu_map to determine valid CPUs for reading RMID counter via the MSR interface. Considering all CPUs associated with the L3 cache improves the chances of picking a housekeeping CPU on which the counter reading work can be queued, avoiding an unnecessary IPI. Fixes: 328ea68874642 ("x86/resctrl: Prepare for new Sub-NUMA Cluster (SNC) monitor files") Signed-off-by: Qinyun Tan Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Tested-by: Tony Luck Link: https://lore.kernel.org/20250530182053.37502-2-qinyuntan@linux.alibaba.com

x86,fs/resctrl: Move the resctrl filesystem code to live in /fs/resctrl

2025-05-16T12:36:09Z

Resctrl is a filesystem interface to hardware that provides cache allocation policy and bandwidth control for groups of tasks or CPUs. To support more than one architecture, resctrl needs to live in /fs/. Move the code that is concerned with the filesystem interface to /fs/resctrl. Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Reviewed-by: Fenghua Yu Tested-by: Fenghua Yu Tested-by: Tony Luck Link: https://lore.kernel.org/20250515165855.31452-25-james.morse@arm.com

fs/resctrl: Add boiler plate for external resctrl code

2025-05-16T09:05:40Z

Add Makefile and Kconfig for fs/resctrl. Add ARCH_HAS_CPU_RESCTRL for the common parts of the resctrl interface and make X86_CPU_RESCTRL select this. Adding an include of asm/resctrl.h to linux/resctrl.h allows the /fs/resctrl files to switch over to using this header instead. 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: Fenghua Yu Reviewed-by: Reinette Chatre Tested-by: Fenghua Yu 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 Tested-by: Tony Luck Link: https://lore.kernel.org/20250515165855.31452-16-james.morse@arm.com