linux-kernel - [PATCH 02/15] x86/resctrl: Remove hard-coded memory bandwidth event configuration

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Date:   Thu, 30 Nov 2023 18:57:07 -0600
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>
CC:     <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
        <rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
        <seanjc@...gle.com>, <kim.phillips@....com>, <babu.moger@....com>,
        <jmattson@...gle.com>, <ilpo.jarvinen@...ux.intel.com>,
        <jithu.joseph@...el.com>, <kan.liang@...ux.intel.com>,
        <nikunj@....com>, <daniel.sneddon@...ux.intel.com>,
        <pbonzini@...hat.com>, <rick.p.edgecombe@...el.com>,
        <rppt@...nel.org>, <maciej.wieczor-retman@...el.com>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <eranian@...gle.com>, <peternewman@...gle.com>, <dhagiani@....com>
Subject: [PATCH 02/15] x86/resctrl: Remove hard-coded memory bandwidth event configuration

If the BMEC (Bandwidth Monitoring Event Configuration) feature is
supported, the bandwidth events can be configured. Currently, the maximum
supported event bitmask is hard-coded. This information can be detected by
the CPUID_Fn80000020_ECX_x03.

CPUID_Fn80000020_ECX_x03 [Platform QoS Monitoring Bandwidth Event
Configuration] Read-only. Reset: 0000_007Fh.
Bits	Description
31:7	Reserved
 6:0	Identifies the bandwidth sources that can be tracked.

Remove the hardcoded value and detect using CPUID command.

The CPUID details are documentation in the PPR listed below [1].
[1] Processor Programming Reference (PPR) Vol 1.1 for AMD Family 19h Model
11h B1 - 55901 Rev 0.25.

Fixes: dc2a3e857981 ("x86/resctrl: Add interface to read mbm_total_bytes_config")
Signed-off-by: Babu Moger <babu.moger@....com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
---
 arch/x86/kernel/cpu/resctrl/internal.h |  4 +---
 arch/x86/kernel/cpu/resctrl/monitor.c  | 11 +++++++++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c |  4 ++--
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index d2979748fae4..524d8bec1439 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -50,9 +50,6 @@
 /* Dirty Victims to All Types of Memory */
 #define DIRTY_VICTIMS_TO_ALL_MEM	BIT(6)
 
-/* Max event bits supported */
-#define MAX_EVT_CONFIG_BITS		GENMASK(6, 0)
-
 struct rdt_fs_context {
 	struct kernfs_fs_context	kfc;
 	bool				enable_cdpl2;
@@ -117,6 +114,7 @@ extern bool rdt_alloc_capable;
 extern bool rdt_mon_capable;
 extern unsigned int rdt_mon_features;
 extern struct list_head resctrl_schema_all;
+extern unsigned int resctrl_max_evt_bitmask;
 
 enum rdt_group_type {
 	RDTCTRL_GROUP = 0,
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index f136ac046851..c611b16ba259 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -127,6 +127,11 @@ static const struct mbm_correction_factor_table {
 static u32 mbm_cf_rmidthreshold __read_mostly = UINT_MAX;
 static u64 mbm_cf __read_mostly;
 
+/*
+ * Identifies the list of QoS Bandwidth Sources to track
+ */
+unsigned int resctrl_max_evt_bitmask;
+
 static inline u64 get_corrected_mbm_count(u32 rmid, unsigned long val)
 {
 	/* Correct MBM value. */
@@ -813,6 +818,12 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 		return ret;
 
 	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);
+		resctrl_max_evt_bitmask = ecx;
+
 		if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
 			mbm_total_event.configurable = true;
 			mbm_config_rftype_init("mbm_total_bytes_config");
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 69a1de92384a..6c22718dbaa2 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1547,7 +1547,7 @@ static void mon_event_config_read(void *info)
 	rdmsrl(MSR_IA32_EVT_CFG_BASE + index, msrval);
 
 	/* Report only the valid event configuration bits */
-	mon_info->mon_config = msrval & MAX_EVT_CONFIG_BITS;
+	mon_info->mon_config = msrval & resctrl_max_evt_bitmask;
 }
 
 static void mondata_config_read(struct rdt_domain *d, struct mon_config_info *mon_info)
@@ -1621,7 +1621,7 @@ static int mbm_config_write_domain(struct rdt_resource *r,
 	int ret = 0;
 
 	/* mon_config cannot be more than the supported set of events */
-	if (val > MAX_EVT_CONFIG_BITS) {
+	if (val > resctrl_max_evt_bitmask) {
 		rdt_last_cmd_puts("Invalid event configuration\n");
 		return -EINVAL;
 	}
-- 
2.34.1