Hi Babu, On 5/15/25 3:51 PM, 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 monitoring counters supported. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > --- ... > --- > arch/x86/kernel/cpu/resctrl/monitor.c | 9 +++++++-- > include/linux/resctrl.h | 4 ++++ > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c > index aeb2a9283069..fd2761d9f3f7 100644 > --- a/arch/x86/kernel/cpu/resctrl/monitor.c > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c > @@ -345,6 +345,7 @@ 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(); > > @@ -375,13 +376,17 @@ 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; > - > /* 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; > } > > + if (rdt_cpu_has(X86_FEATURE_ABMC)) { > + r->mon.mbm_cntr_assignable = true; > + cpuid_count(0x80000020, 5, &eax, &ebx, &ecx, &edx); > + r->mon.num_mbm_cntrs = (ebx & GENMASK(15, 0)) + 1; > + } > + Shouldn't ABMC detection also include enumeration of which configurations are supported? From what I can tell, looking ahead patch #18 hardcodes definitions of all known "bandwidth types" (which term to use TBD) and then patch #20 allows *any* of these types to be configured irrespective of whether system supports it. AMD spec mentions "The types of L3 transactions that ABMC can track are configurable and identified by CPUID Fn8000_0020_ECX_x3." It thus looks like the enumeration of r->mon.mbm_cfg_mask when BMEC is enabled is required for ABMC also and used by this implementation. > r->mon_capable = true; > > return 0; > diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h > index 2a8fa454d3e6..065fb6e38933 100644 > --- a/include/linux/resctrl.h > +++ b/include/linux/resctrl.h > @@ -260,11 +260,15 @@ enum resctrl_schema_fmt { > * @num_rmid: Number of RMIDs available > * @mbm_cfg_mask: Bandwidth sources that can be tracked when bandwidth > * monitoring events can be configured. > + * @num_mbm_cntrs: Number of assignable monitoring counters > + * @mbm_cntr_assignable:Is system capable of supporting monitor assignment? "monitor assignment" has not been used so far, was this intended to be "counter assignment"? Reinette
