linux-kernel - [PATCH v15 21/34] x86/resctrl: Refactor resctrl_arch_rmid

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Message-ID: <7cab88ccc3e0e173271c9b12fce22785bbde9239.1752013061.git.babu.moger@amd.com>
Date: Tue, 8 Jul 2025 17:17:30 -0500
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <tony.luck@...el.com>, <reinette.chatre@...el.com>,
	<james.morse@....com>, <tglx@...utronix.de>, <mingo@...hat.com>,
	<bp@...en8.de>, <dave.hansen@...ux.intel.com>
CC: <Dave.Martin@....com>, <x86@...nel.org>, <hpa@...or.com>,
	<akpm@...ux-foundation.org>, <paulmck@...nel.org>, <rostedt@...dmis.org>,
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	<fvdl@...gle.com>, <seanjc@...gle.com>, <jpoimboe@...nel.org>,
	<pawan.kumar.gupta@...ux.intel.com>, <xin@...or.com>,
	<manali.shukla@....com>, <babu.moger@....com>, <tao1.su@...ux.intel.com>,
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	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<peternewman@...gle.com>, <eranian@...gle.com>
Subject: [PATCH v15 21/34] x86/resctrl: Refactor resctrl_arch_rmid_read()

resctrl_arch_rmid_read() modifies the value obtained from MSR_IA32_QM_CTR
to account for overflow. This adjustment is common to both
resctrl_arch_rmid_read() and resctrl_arch_cntr_read().

To prepare for the implementation of resctrl_arch_cntr_read(), refactor
this logic into a new function called mbm_corrected_val().

Signed-off-by: Babu Moger <babu.moger@....com>
---
v15: New patch to add arch calls resctrl_arch_cntr_read() and resctrl_arch_reset_cntr()
     with mbm_event mode.
     https://lore.kernel.org/lkml/b4b14670-9cb0-4f65-abd5-39db996e8da9@intel.com/
---
 arch/x86/kernel/cpu/resctrl/monitor.c | 38 ++++++++++++++++-----------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 017f3b8e28f9..a230d98e9d73 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -217,15 +217,33 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
 	return chunks >> shift;
 }
 
+static u64 mbm_corrected_val(struct rdt_resource *r, struct rdt_mon_domain *d,
+			     u32 rmid, enum resctrl_event_id eventid, u64 msr_val)
+{
+	struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+	struct arch_mbm_state *am;
+	u64 chunks;
+
+	am = get_arch_mbm_state(hw_dom, rmid, eventid);
+	if (am) {
+		am->chunks += mbm_overflow_count(am->prev_msr, msr_val,
+				hw_res->mbm_width);
+		chunks = get_corrected_mbm_count(rmid, am->chunks);
+		am->prev_msr = msr_val;
+	} else {
+		chunks = msr_val;
+	}
+
+	return chunks * hw_res->mon_scale;
+}
+
 int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_mon_domain *d,
 			   u32 unused, u32 rmid, enum resctrl_event_id eventid,
 			   u64 *val, void *ignored)
 {
-	struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
-	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 	int cpu = cpumask_any(&d->hdr.cpu_mask);
-	struct arch_mbm_state *am;
-	u64 msr_val, chunks;
+	u64 msr_val;
 	u32 prmid;
 	int ret;
 
@@ -236,17 +254,7 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_mon_domain *d,
 	if (ret)
 		return ret;
 
-	am = get_arch_mbm_state(hw_dom, rmid, eventid);
-	if (am) {
-		am->chunks += mbm_overflow_count(am->prev_msr, msr_val,
-						 hw_res->mbm_width);
-		chunks = get_corrected_mbm_count(rmid, am->chunks);
-		am->prev_msr = msr_val;
-	} else {
-		chunks = msr_val;
-	}
-
-	*val = chunks * hw_res->mon_scale;
+	*val = mbm_corrected_val(r, d, rmid, eventid, msr_val);
 
 	return 0;
 }
-- 
2.34.1