[PATCH v1 29/40] x86/cpu: Use enums for TLB descriptor types

Ahmed S. Darwish
2025-03-04T08:53:42Z

The leaf 0x2 one-byte TLB descriptor types:

TLB_INST_4K
TLB_INST_4M
TLB_INST_2M_4M
...

are just discriminators to be used within the intel_tlb_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 intel_tlb_table[] size do not go out of hand.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
---
arch/x86/include/asm/cpuid/types.h | 26 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/intel.c | 28 +++-------------------------
2 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/arch/x86/include/asm/cpuid/types.h b/arch/x86/include/asm/cpuid/types.h
index 0051d8c2b9ee..2a4653af2ba2 100644
--- a/arch/x86/include/asm/cpuid/types.h
+++ b/arch/x86/include/asm/cpuid/types.h
@@ -90,4 +90,30 @@ enum _cache_table_type {
} __packed;
static_assert(sizeof(enum _cache_table_type) == 1);

+/*
+ * Leaf 0x2 1-byte descriptors' TLB types
+ * To be used for their mappings at intel_tlb_table[]
+ */
+enum _tlb_table_type {
+ TLB_INST_4K,
+ TLB_INST_4M,
+ TLB_INST_2M_4M,
+ TLB_INST_ALL,
+
+ TLB_DATA_4K,
+ TLB_DATA_4M,
+ TLB_DATA_2M_4M,
+ TLB_DATA_4K_4M,
+ TLB_DATA_1G,
+ TLB_DATA_1G_2M_4M,
+
+ TLB_DATA0_4K,
+ TLB_DATA0_4M,
+ TLB_DATA0_2M_4M,
+
+ STLB_4K,
+ STLB_4K_2M,
+} __packed;
+static_assert(sizeof(enum _tlb_table_type) == 1);
+
#endif /* _ASM_X86_CPUID_TYPES_H */
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 57e170ffe3ba..884cd1b1e4ff 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -626,28 +626,6 @@ static unsigned int intel_size_cache(struct cpuinfo_x86 *c, unsigned int size)
}
#endif

-#define TLB_INST_4K 0x01
-#define TLB_INST_4M 0x02
-#define TLB_INST_2M_4M 0x03
-
-#define TLB_INST_ALL 0x05
-#define TLB_INST_1G 0x06
-
-#define TLB_DATA_4K 0x11
-#define TLB_DATA_4M 0x12
-#define TLB_DATA_2M_4M 0x13
-#define TLB_DATA_4K_4M 0x14
-
-#define TLB_DATA_1G 0x16
-#define TLB_DATA_1G_2M_4M 0x17
-
-#define TLB_DATA0_4K 0x21
-#define TLB_DATA0_4M 0x22
-#define TLB_DATA0_2M_4M 0x23
-
-#define STLB_4K 0x41
-#define STLB_4K_2M 0x42
-
/*
* All of leaf 0x2's one-byte TLB descriptors implies the same number of
* entries for their respective TLB types. The 0x63 descriptor is an
@@ -660,7 +638,7 @@ static unsigned int intel_size_cache(struct cpuinfo_x86 *c, unsigned int size)

struct _tlb_table {
unsigned char descriptor;
- char tlb_type;
+ enum _tlb_table_type type;
unsigned int entries;
};

@@ -718,11 +696,11 @@ static void intel_tlb_lookup(const unsigned char desc)
intel_tlb_table[k].descriptor != 0; k++)
;

- if (intel_tlb_table[k].tlb_type == 0)
+ if (intel_tlb_table[k].type == 0)
return;

entries = intel_tlb_table[k].entries;
- switch (intel_tlb_table[k].tlb_type) {
+ switch (intel_tlb_table[k].type) {
case STLB_4K:
tlb_lli_4k = max(tlb_lli_4k, entries);
tlb_lld_4k = max(tlb_lld_4k, entries);
--
2.48.1