linux-kernel - [PATCH v5 04/20] x86/resctrl: Detect Assignable Bandwidth Monitoring feature details

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Message-ID: <ea967681e5ed7a9c27771d60ef993616e7e1292e.1720043311.git.babu.moger@amd.com>
Date: Wed, 3 Jul 2024 16:48:15 -0500
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <fenghua.yu@...el.com>, <reinette.chatre@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
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	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
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Subject: [PATCH v5 04/20] x86/resctrl: Detect Assignable Bandwidth Monitoring feature details

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@....com>
---
v5: Name change num_cntrs to num_mbm_cntrs.
    Moved abmc_capable to resctrl_mon.

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 | 12 ++++++++++++
 include/linux/resctrl.h               |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 795fe91a8feb..87d40f149ebc 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -1229,6 +1229,18 @@ 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->mon.abmc_capable = true;
+			/*
+			 * Query CPUID_Fn80000020_EBX_x05 for number of
+			 * ABMC counters
+			 */
+			cpuid_count(0x80000020, 5, &eax, &ebx, &ecx, &edx);
+			r->mon.num_mbm_cntrs = (ebx & 0xFFFF) + 1;
+			if (WARN_ON(r->mon.num_mbm_cntrs > 64))
+				r->mon.num_mbm_cntrs = 64;
+		}
 	}
 
 	l3_mon_evt_init(r);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index e43fc5bb5a3a..62f0f002ef41 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -185,10 +185,14 @@ enum resctrl_scope {
 /**
  * struct resctrl_mon - Monitoring related data
  * @num_rmid:		Number of RMIDs available
+ * @num_mbm_cntrs:	Number of monitoring counters
+ * @abmc_capable:	Is system capable of supporting monitor assignment?
  * @evt_list:		List of monitoring events
  */
 struct resctrl_mon {
 	int			num_rmid;
+	int			num_mbm_cntrs;
+	bool			abmc_capable;
 	struct list_head	evt_list;
 };
 
-- 
2.34.1