linux-kernel - [PATCH v5 31/35] x86/cacheinfo: Use parsed CPUID(0x80000006)

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Message-ID: <20250905121515.192792-32-darwi@linutronix.de>
Date: Fri,  5 Sep 2025 14:15:11 +0200
From: "Ahmed S. Darwish" <darwi@...utronix.de>
To: Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Sean Christopherson <seanjc@...gle.com>,
	David Woodhouse <dwmw2@...radead.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Sohil Mehta <sohil.mehta@...el.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 v5 31/35] x86/cacheinfo: Use parsed CPUID(0x80000006)

For the AMD cacheinfo logic, use parsed CPUID(0x80000006) access instead
of a direct CPUID query.

Beside the CPUID parser centralization benefits, this allows using the
auto-generated <asm/cpuid/leaf_types.h> data types, and their full C99
bitfields, instead of doing ugly bitwise operations on CPUID register
output.

For testing L3 cache availability, just check if CPUID(0x80000006) EDX
l3_assoc output is not zero.  Per AMD manuals, an L3 associativity of
zero implies the absence of an L3 cache on the CPU.

Since cpuid_amd_hygon_has_l3_cache() is now using the CPUID parser API,
move its definition under the header file section: "Convenience leaf
specific functions (using parsed CPUID data)"

Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
---
 arch/x86/include/asm/cpuid/api.h | 18 +++++++++---------
 arch/x86/kernel/amd_nb.c         |  3 ++-
 arch/x86/kernel/cpu/cacheinfo.c  |  6 +++---
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/cpuid/api.h b/arch/x86/include/asm/cpuid/api.h
index 2989a0c83ab0..c8efbd013504 100644
--- a/arch/x86/include/asm/cpuid/api.h
+++ b/arch/x86/include/asm/cpuid/api.h
@@ -213,15 +213,6 @@ static inline u32 cpuid_base_hypervisor(const char *sig, u32 leaves)
 	return 0;
 }
 
-/*
- * CPUID(0x80000006) parsing:
- */
-
-static inline bool cpuid_amd_hygon_has_l3_cache(void)
-{
-	return cpuid_edx(0x80000006);
-}
-
 /*
  * 'struct cpuid_leaves' accessors (without sanity checks):
  *
@@ -538,6 +529,15 @@ static inline bool cpuid_amd_hygon_has_l3_cache(void)
 	     _ptr < &((union leaf_0x2_regs *)(_regs))->desc[16] && (_desc = &cpuid_0x2_table[*_ptr]);\
 	     _ptr++)
 
+/*
+ * CPUID(0x80000006)
+ */
+
+static inline bool cpuid_amd_hygon_has_l3_cache(struct cpuinfo_x86 *c)
+{
+	return cpuid_leaf(c, 0x80000006)->l3_assoc;
+}
+
 /*
  * CPUID parser exported APIs:
  */
diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index c1acead6227a..04a1965f10fe 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -16,6 +16,7 @@
 
 #include <asm/amd/nb.h>
 #include <asm/cpuid/api.h>
+#include <asm/processor.h>
 
 static u32 *flush_words;
 
@@ -93,7 +94,7 @@ static int amd_cache_northbridges(void)
 	if (amd_gart_present())
 		amd_northbridges.flags |= AMD_NB_GART;
 
-	if (!cpuid_amd_hygon_has_l3_cache())
+	if (!cpuid_amd_hygon_has_l3_cache(&boot_cpu_data))
 		return 0;
 
 	/*
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 7033baa94276..c5c6b0740e0d 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -235,7 +235,7 @@ static unsigned int get_cache_id(u32 apicid, const struct _cpuid4_info *id4)
 
 void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, u16 die_id)
 {
-	if (!cpuid_amd_hygon_has_l3_cache())
+	if (!cpuid_amd_hygon_has_l3_cache(c))
 		return;
 
 	if (c->x86 < 0x17) {
@@ -262,7 +262,7 @@ void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, u16 die_id)
 
 void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c)
 {
-	if (!cpuid_amd_hygon_has_l3_cache())
+	if (!cpuid_amd_hygon_has_l3_cache(c))
 		return;
 
 	/*
@@ -278,7 +278,7 @@ void init_amd_cacheinfo(struct cpuinfo_x86 *c)
 
 	ci->num_leaves = boot_cpu_has(X86_FEATURE_TOPOEXT) ?
 		cpuid_subleaf_count(c, 0x8000001d) :
-		cpuid_leaf(c, 0x80000006)->l3_assoc ? 4 : 3;
+		cpuid_amd_hygon_has_l3_cache(c) ? 4 : 3;
 }
 
 void init_hygon_cacheinfo(struct cpuinfo_x86 *c)
-- 
2.50.1