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x86,fs/resctrl: Detect Assignable Bandwidth Monitoring feature details

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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 ABMC feature details are documented in APM [1] available from [2].

  [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.

Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537 # [2]
This commit is contained in:
Babu Moger 2025-09-05 16:34:07 -05:00 committed by Borislav Petkov (AMD)
parent 5ad68c8f96
commit 13390861b4
4 changed files with 24 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

7
arch/x86/kernel/cpu/resctrl/core.c
View file

@ -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;
@ -978,7 +980,7 @@ static enum cpuhp_state rdt_online;
/* Runs once on the BSP during boot. */
void resctrl_cpu_detect(struct cpuinfo_x86 *c)
{
if (!cpu_has(c, X86_FEATURE_CQM_LLC)) {
if (!cpu_has(c, X86_FEATURE_CQM_LLC) && !cpu_has(c, X86_FEATURE_ABMC)) {
c->x86_cache_max_rmid = -1;
c->x86_cache_occ_scale = -1;
c->x86_cache_mbm_width_offset = -1;
@ -990,7 +992,8 @@ void resctrl_cpu_detect(struct cpuinfo_x86 *c)
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 */

11
arch/x86/kernel/cpu/resctrl/monitor.c
View file

@ -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;
}
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;
}
r->mon_capable = true;
return 0;

7
fs/resctrl/monitor.c
View file

@ -922,6 +922,13 @@ int resctrl_mon_resource_init(void)
else if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
mba_mbps_default_event = QOS_L3_MBM_TOTAL_EVENT_ID;
if (r->mon.mbm_cntr_assignable) {
if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
}
return 0;
}

4
include/linux/resctrl.h
View file

@ -260,10 +260,14 @@ enum resctrl_schema_fmt {
* @num_rmid: Number of RMIDs available.
* @mbm_cfg_mask: Memory transactions that can be tracked when bandwidth
* monitoring events can be configured.
* @num_mbm_cntrs: Number of assignable counters.
* @mbm_cntr_assignable:Is system capable of supporting counter assignment?
*/
struct resctrl_mon {
int num_rmid;
unsigned int mbm_cfg_mask;
int num_mbm_cntrs;
bool mbm_cntr_assignable;
};
/**