linux-kernel - [PATCH v2 18/29] x86/cacheinfo: Use enums for cache descriptor types

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Message-ID: <20250317164745.4754-19-darwi@linutronix.de>
Date: Mon, 17 Mar 2025 17:47:34 +0100
From: "Ahmed S. Darwish" <darwi@...utronix.de>
To: Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	John Ogness <john.ogness@...utronix.de>,
	x86@...nel.org,
	x86-cpuid@...ts.linux.dev,
	LKML <linux-kernel@...r.kernel.org>,
	"Ahmed S. Darwish" <darwi@...utronix.de>
Subject: [PATCH v2 18/29] x86/cacheinfo: Use enums for cache descriptor types

The leaf 0x2 one-byte cache descriptor types:

	CACHE_L1_INST
	CACHE_L1_DATA
	CACHE_L2
	CACHE_L3

are just discriminators to be used within the cache_table[] mapping.
Their specific values are irrelevant.

Use enums for such types.

Make the enum packed and static assert that its values remain within a
single byte so that the cache_table[] array size do not go out of hand.

Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
---
 arch/x86/include/asm/cpuid/types.h | 13 +++++++++++++
 arch/x86/kernel/cpu/cacheinfo.c    |  9 ++-------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/cpuid/types.h b/arch/x86/include/asm/cpuid/types.h
index 864047113e37..a66192f9df4c 100644
--- a/arch/x86/include/asm/cpuid/types.h
+++ b/arch/x86/include/asm/cpuid/types.h
@@ -2,6 +2,7 @@
 #ifndef _ASM_X86_CPUID_TYPES_H
 #define _ASM_X86_CPUID_TYPES_H
 
+#include <linux/build_bug.h>
 #include <linux/types.h>
 
 /*
@@ -42,4 +43,16 @@ union leaf_0x2_regs {
 	u8			desc[16];
 };
 
+/*
+ * Leaf 0x2 1-byte descriptors' cache types
+ * To be used for their mappings at cache_table[]
+ */
+enum _cache_table_type {
+	CACHE_L1_INST,
+	CACHE_L1_DATA,
+	CACHE_L2,
+	CACHE_L3
+} __packed;
+static_assert(sizeof(enum _cache_table_type) == 1);
+
 #endif /* _ASM_X86_CPUID_TYPES_H */
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 777f95c86e03..9f5bf57fd4fc 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -23,11 +23,6 @@
 
 #include "cpu.h"
 
-#define CACHE_L1_INST	1
-#define CACHE_L1_DATA	2
-#define CACHE_L2	3
-#define CACHE_L3	4
-
 /* Shared last level cache maps */
 DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
 
@@ -41,7 +36,7 @@ unsigned int memory_caching_control __ro_after_init;
 
 struct _cache_table {
 	unsigned char descriptor;
-	char cache_type;
+	enum _cache_table_type type;
 	short size;
 };
 
@@ -517,7 +512,7 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c)
 			if (!entry)
 				continue;
 
-			switch (entry->cache_type) {
+			switch (entry->type) {
 			case CACHE_L1_INST:	l1i += entry->size; break;
 			case CACHE_L1_DATA:	l1d += entry->size; break;
 			case CACHE_L2:		l2  += entry->size; break;
-- 
2.48.1