linux-kernel - [tip: x86/cache] x86/resctrl: Refactor resctrl_arch_rmid

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Message-ID: <175793565346.709179.5878050433454885901.tip-bot2@tip-bot2>
Date: Mon, 15 Sep 2025 11:27:33 -0000
From: "tip-bot2 for Babu Moger" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Babu Moger <babu.moger@....com>, "Borislav Petkov (AMD)" <bp@...en8.de>,
 Reinette Chatre <reinette.chatre@...el.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/cache] x86/resctrl: Refactor resctrl_arch_rmid_read()

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     7c9ac605e202c4668e441fc8146a993577131ca1
Gitweb:        https://git.kernel.org/tip/7c9ac605e202c4668e441fc8146a993577131ca1
Author:        Babu Moger <babu.moger@....com>
AuthorDate:    Fri, 05 Sep 2025 16:34:20 -05:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 15 Sep 2025 12:28:21 +02:00

x86/resctrl: Refactor resctrl_arch_rmid_read()

resctrl_arch_rmid_read() adjusts the value obtained from MSR_IA32_QM_CTR to
account for the overflow for MBM events and apply counter scaling for all the
events. This logic is common to both reading an RMID and reading a hardware
counter directly.

Refactor the hardware value adjustment logic into get_corrected_val() to
prepare for support of reading a hardware counter.

Signed-off-by: Babu Moger <babu.moger@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.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 ed295a6..1f77fd5 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -217,24 +217,13 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
 	return chunks >> shift;
 }
 
-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)
+static u64 get_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);
-	int cpu = cpumask_any(&d->hdr.cpu_mask);
 	struct arch_mbm_state *am;
-	u64 msr_val, chunks;
-	u32 prmid;
-	int ret;
-
-	resctrl_arch_rmid_read_context_check();
-
-	prmid = logical_rmid_to_physical_rmid(cpu, rmid);
-	ret = __rmid_read_phys(prmid, eventid, &msr_val);
-	if (ret)
-		return ret;
+	u64 chunks;
 
 	am = get_arch_mbm_state(hw_dom, rmid, eventid);
 	if (am) {
@@ -246,7 +235,26 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_mon_domain *d,
 		chunks = msr_val;
 	}
 
-	*val = chunks * hw_res->mon_scale;
+	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)
+{
+	int cpu = cpumask_any(&d->hdr.cpu_mask);
+	u64 msr_val;
+	u32 prmid;
+	int ret;
+
+	resctrl_arch_rmid_read_context_check();
+
+	prmid = logical_rmid_to_physical_rmid(cpu, rmid);
+	ret = __rmid_read_phys(prmid, eventid, &msr_val);
+	if (ret)
+		return ret;
+
+	*val = get_corrected_val(r, d, rmid, eventid, msr_val);
 
 	return 0;
 }