[patch V4 23/41] x86/cpu: Provide cpuid_read() et al.

Thomas Gleixner
2023-08-14T08:56:08Z

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@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>

---
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, regs + 1, regs + 2, regs + 3);
+}
+
+#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) {