linux-kernel - [PATCH v4 12/19] x86/resctrl: Remove MSR reading of event configuration value

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Date: Fri, 24 May 2024 07:23:31 -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>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <babu.moger@....com>, <kim.phillips@....com>,
	<lukas.bulwahn@...il.com>, <seanjc@...gle.com>, <jmattson@...gle.com>,
	<leitao@...ian.org>, <jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
	<kirill.shutemov@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kai.huang@...el.com>, <kan.liang@...ux.intel.com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<sandipan.das@....com>, <ilpo.jarvinen@...ux.intel.com>,
	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>, <james.morse@....com>
Subject: [PATCH v4 12/19] x86/resctrl: Remove MSR reading of event configuration value

The event configuration is domain specific and initialized during domain
initialization. It is not required to read the configuration register
every time user asks for it. Use the value stored in rdt_hw_domain instead.

Signed-off-by: Babu Moger <babu.moger@....com>
---
v4: New patch.
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 55 ++++++++++++--------------
 1 file changed, 25 insertions(+), 30 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index c176bacf7ba1..0e425c91fa46 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1618,46 +1618,30 @@ static inline unsigned int mon_event_config_index_get(u32 evtid)
 	}
 }
 
-static void mon_event_config_read(void *info)
-{
-	struct mon_config_info *mon_info = info;
-	unsigned int index;
-	u64 msrval;
-
-	index = mon_event_config_index_get(mon_info->evtid);
-	if (index == INVALID_CONFIG_INDEX) {
-		pr_warn_once("Invalid event id %d\n", mon_info->evtid);
-		return;
-	}
-	rdmsrl(MSR_IA32_EVT_CFG_BASE + index, msrval);
-
-	/* Report only the valid event configuration bits */
-	mon_info->mon_config = msrval & MAX_EVT_CONFIG_BITS;
-}
-
-static void mondata_config_read(struct rdt_domain *d, struct mon_config_info *mon_info)
-{
-	smp_call_function_any(&d->cpu_mask, mon_event_config_read, mon_info, 1);
-}
-
 static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid)
 {
-	struct mon_config_info mon_info = {0};
 	struct rdt_domain *dom;
 	bool sep = false;
+	u32 val;
 
 	cpus_read_lock();
 	mutex_lock(&rdtgroup_mutex);
 
 	list_for_each_entry(dom, &r->domains, list) {
+		struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(dom);
 		if (sep)
 			seq_puts(s, ";");
 
-		memset(&mon_info, 0, sizeof(struct mon_config_info));
-		mon_info.evtid = evtid;
-		mondata_config_read(dom, &mon_info);
+		if (evtid == QOS_L3_MBM_TOTAL_EVENT_ID) {
+			val = hw_dom->mbm_total_cfg;
+		} else if (evtid == QOS_L3_MBM_LOCAL_EVENT_ID) {
+			val = hw_dom->mbm_local_cfg;
+		} else {
+			pr_warn_once("Invalid event id %d\n", evtid);
+			break;
+		}
 
-		seq_printf(s, "%d=0x%02x", dom->id, mon_info.mon_config);
+		seq_printf(s, "%d=0x%02x", dom->id, val);
 		sep = true;
 	}
 	seq_puts(s, "\n");
@@ -1704,17 +1688,28 @@ static void mon_event_config_write(void *info)
 static void mbm_config_write_domain(struct rdt_resource *r,
 				    struct rdt_domain *d, u32 evtid, u32 val)
 {
+	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
 	struct mon_config_info mon_info = {0};
 
 	/*
 	 * Read the current config value first. If both are the same then
 	 * no need to write it again.
 	 */
-	mon_info.evtid = evtid;
-	mondata_config_read(d, &mon_info);
-	if (mon_info.mon_config == val)
+	switch (evtid) {
+	case QOS_L3_MBM_TOTAL_EVENT_ID:
+		if (val == hw_dom->mbm_total_cfg)
+			return;
+		break;
+	case QOS_L3_MBM_LOCAL_EVENT_ID:
+		if (val == hw_dom->mbm_local_cfg)
+			return;
+		break;
+	default:
+		pr_warn_once("Invalid event id %d\n", evtid);
 		return;
+	}
 
+	mon_info.evtid = evtid;
 	mon_info.mon_config = val;
 
 	/*
-- 
2.34.1