Hi Reinette, On 7/30/25 14:49, Reinette Chatre wrote: > Hi Babu, > > On 7/25/25 11:29 AM, Babu Moger wrote: >> ABMC feature details are reported via CPUID Fn8000_0020_EBX_x5. >> Bits Description >> 15:0 MAX_ABMC Maximum Supported Assignable Bandwidth >> Monitoring Counter ID + 1 >> >> The feature details are documented in APM listed below [1]. >> [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming >> Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth >> Monitoring (ABMC). >> >> Detect the feature and number of assignable counters supported. For >> backward compatibility, upon detecting the assignable counter feature, >> enable the mbm_total_bytes and mbm_local_bytes events that users are >> familiar with as part of original L3 MBM support. >> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 >> Signed-off-by: Babu Moger <babu.moger@xxxxxxx> >> --- > > ... > >> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c >> index 267e9206a999..09cb5a70b1cb 100644 >> --- a/arch/x86/kernel/cpu/resctrl/core.c >> +++ b/arch/x86/kernel/cpu/resctrl/core.c >> @@ -883,6 +883,8 @@ static __init bool get_rdt_mon_resources(void) >> resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID); >> ret = true; >> } >> + if (rdt_cpu_has(X86_FEATURE_ABMC)) >> + ret = true; >> >> if (!ret) >> return false; >> @@ -990,7 +992,8 @@ void resctrl_cpu_detect(struct cpuinfo_x86 *c) >> > > To complement the change below, shouldn't the snippet that precedes it look like: > if (!cpu_has(c, X86_FEATURE_CQM_LLC) && !cpu_has(c, X86_FEATURE_ABMC)) { > ... > return; > } Sure. Added now. > >> if (cpu_has(c, X86_FEATURE_CQM_OCCUP_LLC) || >> cpu_has(c, X86_FEATURE_CQM_MBM_TOTAL) || >> - cpu_has(c, X86_FEATURE_CQM_MBM_LOCAL)) { >> + cpu_has(c, X86_FEATURE_CQM_MBM_LOCAL) || >> + cpu_has(c, X86_FEATURE_ABMC)) { >> u32 eax, ebx, ecx, edx; >> >> /* QoS sub-leaf, EAX=0Fh, ECX=1 */ >> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c >> index 2558b1bdef8b..0a695ce68f46 100644 >> --- a/arch/x86/kernel/cpu/resctrl/monitor.c >> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c >> @@ -339,6 +339,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r) >> unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset; >> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); >> unsigned int threshold; >> + u32 eax, ebx, ecx, edx; >> >> snc_nodes_per_l3_cache = snc_get_config(); >> >> @@ -368,14 +369,18 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r) >> */ >> resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(threshold); >> >> - if (rdt_cpu_has(X86_FEATURE_BMEC)) { >> - u32 eax, ebx, ecx, edx; >> - >> + if (rdt_cpu_has(X86_FEATURE_BMEC) || rdt_cpu_has(X86_FEATURE_ABMC)) { >> /* Detect list of bandwidth sources that can be tracked */ >> cpuid_count(0x80000020, 3, &eax, &ebx, &ecx, &edx); >> r->mon.mbm_cfg_mask = ecx & MAX_EVT_CONFIG_BITS; > > I interpret this mbm_cfg_mask initialization that an ABMC system will report which of > the memory transactions can be monitored. > In patch #15 "fs/resctrl: Introduce event configuration field in struct mon_evt" > the event configurations of memory transactions that should be monitored are hardcoded > as below without taking into account what the system supports: > > resctrl_mon_resource_init() { > ... > mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = MAX_EVT_CONFIG_BITS; > mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg = READS_TO_LOCAL_MEM | > READS_TO_LOCAL_S_MEM | > NON_TEMP_WRITE_TO_LOCAL_MEM; > ... > } That is correct. Changed the assignment. mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = r->mon.mbm_cfg_mask; mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg = r->mon.mbm_cfg_mask & (READS_TO_LOCAL_MEM | READS_TO_LOCAL_S_MEM | NON_TEMP_WRITE_TO_LOCAL_MEM); > > It may thus be that a system may not support all memory transactions it is configured to > monitor. It seems to me that the initialization done in resctrl_mon_resource_init() needs > to take r->mon.mbm_cfg_mask (what the system supports) into account? If so, then > the same hardcoding done by patch #32 in resctrl_mbm_assign_mode_write() should > also be changed. Yes. Sure. -- Thanks Babu Moger
