[PATCH v4 04/19] x86/resctrl: Detect Assignable Bandwidth Monitoring feature details

Babu Moger
2024-05-24T12:24:25Z

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).

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v4: Removed resctrl_arch_has_abmc(). Added all the code inline. We dont
need to separate this as arch code.

v3: Removed changes related to mon_features.
Moved rdt_cpu_has to core.c and added new function resctrl_arch_has_abmc.
Also moved the fields mbm_assign_capable and mbm_assign_cntrs to
rdt_resource. (James)

v2: Changed the field name to mbm_assign_capable from abmc_capable.
---
arch/x86/kernel/cpu/resctrl/monitor.c | 14 ++++++++++++++
include/linux/resctrl.h | 4 ++++
2 files changed, 18 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index b35d04fc761b..1602b58ba23d 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -1066,6 +1066,20 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
mbm_local_event.configurable = true;
mbm_config_rftype_init("mbm_local_bytes_config");
}
+
+ if (rdt_cpu_has(X86_FEATURE_ABMC)) {
+ r->abmc_capable = true;
+ /*
+ * Query CPUID_Fn80000020_EBX_x05 for number of
+ * ABMC counters
+ */
+ cpuid_count(0x80000020, 5, &eax, &ebx, &ecx, &edx);
+ r->mon.num_cntrs = (ebx & 0xFFFF) + 1;
+ if (r->mon.num_cntrs > 64) {
+ WARN(1, "Cannot support more than 64 ABMC counters\n");
+ r->mon.num_cntrs = 64;
+ }
+ }
}

l3_mon_evt_init(r);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index bf99eb9c6ce4..24087e6efbb6 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -153,10 +153,12 @@ struct resctrl_schema;
/**
* struct resctrl_mon - Monitoring related data
* @num_rmid: Number of RMIDs available
+ * @num_cntrs: Maximum number of abmc counters
* @evt_list: List of monitoring events
*/
struct resctrl_mon {
int num_rmid;
+ int num_cntrs;
struct list_head evt_list;
};

@@ -177,6 +179,7 @@ struct resctrl_mon {
* @parse_ctrlval: Per resource function pointer to parse control values
* @fflags: flags to choose base and info files
* @cdp_capable: Is the CDP feature available on this resource
+ * @abmc_capable: Is system capable of supporting monitor assignment?
*/
struct rdt_resource {
int rid;
@@ -196,6 +199,7 @@ struct rdt_resource {
struct rdt_domain *d);
unsigned long fflags;
bool cdp_capable;
+ bool abmc_capable;
};

/**
--
2.34.1