linux-kernel - [patch V6a 01/19] x86/cpu: Provide cpuid

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Date: Wed, 14 Feb 2024 21:29:39 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org, Tom Lendacky <thomas.lendacky@....com>, Andrew Cooper
 <andrew.cooper3@...rix.com>, Arjan van de Ven <arjan@...ux.intel.com>,
 Huang Rui <ray.huang@....com>, Juergen Gross <jgross@...e.com>, Dimitri
 Sivanich <dimitri.sivanich@....com>, Sohil Mehta <sohil.mehta@...el.com>,
 K Prateek Nayak <kprateek.nayak@....com>, Kan Liang
 <kan.liang@...ux.intel.com>, Zhang Rui <rui.zhang@...el.com>, "Paul E.
 McKenney" <paulmck@...nel.org>, Feng Tang <feng.tang@...el.com>, Andy
 Shevchenko <andy@...radead.org>, Michael Kelley <mhklinux@...look.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, Wang Wendy
 <wendy.wang@...el.com>
Subject: [patch V6a 01/19] x86/cpu: Provide cpuid_read() et al.

Provide a few helper functions to read CPUID leafs or individual registers
into a data structure without requiring unions.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Juergen Gross <jgross@...e.com>
Tested-by: Sohil Mehta <sohil.mehta@...el.com>
Tested-by: Michael Kelley <mhklinux@...look.com>
Tested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: Zhang Rui <rui.zhang@...el.com>
Tested-by: Wang Wendy <wendy.wang@...el.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
V6a: Use CPUID_E*X instead of hardcoded numbers - Borislav
---
 arch/x86/include/asm/cpuid.h |   36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
---

--- a/arch/x86/include/asm/cpuid.h
+++ b/arch/x86/include/asm/cpuid.h
@@ -127,6 +127,42 @@ static inline unsigned int cpuid_edx(uns
 	return edx;
 }

+static inline void __cpuid_read(unsigned int leaf, unsigned int subleaf, u32 *regs)
+{
+	regs[CPUID_EAX] = leaf;
+	regs[CPUID_ECX] = subleaf;
+	__cpuid(regs + CPUID_EAX, regs + CPUID_EBX, regs + CPUID_ECX, regs + CPUID_EDX);
+}
+
+#define cpuid_subleaf(leaf, subleaf, regs) {		\
+	BUILD_BUG_ON(sizeof(*(regs)) != 16);		\
+	__cpuid_read(leaf, subleaf, (u32 *)(regs));	\
+}
+
+#define cpuid_leaf(leaf, regs) {			\
+	BUILD_BUG_ON(sizeof(*(regs)) != 16);		\
+	__cpuid_read(leaf, 0, (u32 *)(regs));		\
+}
+
+static inline void __cpuid_read_reg(unsigned int leaf, unsigned int subleaf,
+				    enum cpuid_regs_idx regidx, u32 *reg)
+{
+	u32 regs[4];
+
+	__cpuid_read(leaf, subleaf, regs);
+	*reg = regs[regidx];
+}
+
+#define cpuid_subleaf_reg(leaf, subleaf, regidx, reg) {		\
+	BUILD_BUG_ON(sizeof(*(reg)) != 4);			\
+	__cpuid_read_reg(leaf, subleaf, regidx, (u32 *)(reg));	\
+}
+
+#define cpuid_leaf_reg(leaf, regidx, reg) {			\
+	BUILD_BUG_ON(sizeof(*(reg)) != 4);			\
+	__cpuid_read_reg(leaf, 0, regidx, (u32 *)(reg));	\
+}
+
 static __always_inline bool cpuid_function_is_indexed(u32 function)
 {
 	switch (function) {