linux-kernel - [PATCH 6/6] cacheinfo: Add cacheinfo_get_cache

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Message-Id: <20211216233125.1130793-7-robh@kernel.org>
Date:   Thu, 16 Dec 2021 17:31:25 -0600
From:   Rob Herring <robh@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        James Morse <james.morse@....com>,
        Jeremy Linton <jeremy.linton@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sudeep Holla <sudeep.holla@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, devicetree@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: [PATCH 6/6] cacheinfo: Add cacheinfo_get_cache_affinity() function

Add a cacheinfo_get_cache_affinity() function to retrieve the CPU affinity
mask for a given cache identified by level and cache id.

This is needed by Arm MPAM to get the CPU affinity of MPAM enabled caches.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>
Signed-off-by: Rob Herring <robh@...nel.org>
---
 include/linux/cacheinfo.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 37652cfdd8dc..5e72420cdc75 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -123,4 +123,28 @@ static inline int get_cpu_cacheinfo_id(int cpu, int level)
 	return -1;
 }
 
+/*
+ * Get the CPU affinity of the cache associated with @cpu at level @level and
+ * with identifier @id.
+ * cpuhp lock must be held.
+ */
+static inline int cacheinfo_get_cache_affinity(int cpu, int level, int id,
+					       cpumask_t *mask)
+{
+	struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
+	int i;
+
+	for (i = 0; ci->info_list && i < ci->num_leaves; i++) {
+		if ((ci->info_list[i].level == level) &&
+		    (ci->info_list[i].attributes & CACHE_ID) &&
+		    (ci->info_list[i].id == id)) {
+			cpumask_copy(mask, &ci->info_list[i].cpu_affinity_map);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+
 #endif /* _LINUX_CACHEINFO_H */
-- 
2.32.0