Re: [PATCH v6 21/90] x86/cpuid: Split parser tables and add vendor-qualified parsing

On 2026-03-27 at 03:15:35 +0100, Ahmed S. Darwish wrote:
>diff --git a/arch/x86/kernel/cpu/cpuid_parser.h b/arch/x86/kernel/cpu/cpuid_parser.h
>index 3e11e13fa76c..a3f7dcc6c03f 100644
>--- a/arch/x86/kernel/cpu/cpuid_parser.h
>+++ b/arch/x86/kernel/cpu/cpuid_parser.h
>@@ -109,16 +110,63 @@ struct cpuid_parse_entry {
> 	__CPUID_PARSE_ENTRY(_leaf, __cpuid_leaf_first_subleaf(_leaf), n, _reader_fn)
> 
> /*
>- * CPUID parser table:
>+ * CPUID parser tables:
>  */
> 
>-#define CPUID_PARSE_ENTRIES									\
>+/*
>+ * Early-boot CPUID leaves (to be parsed before x86 vendor detection)
>+ *
>+ * These leaves must be parsed at early boot to identify the x86 vendor. The
>+ * parser treats them as universally valid across all vendors.
>+ *
>+ * At early boot, only leaves in this table must be parsed.  For all other
>+ * leaves, the CPUID parser will assume that "boot_cpu_data.x86_vendor" is
>+ * properly set beforehand.
>+ *
>+ * Note: If these entries are to be modified, please adapt the kernel-doc of
>+ * cpuid_scan_cpu_early() accordingly.
>+ */
>+#define CPUID_EARLY_ENTRIES									\
> 	/*			Leaf		Subleaf		Reader function */		\
> 	CPUID_PARSE_ENTRY   (	0x0,		0,		generic			),	\
> 	CPUID_PARSE_ENTRY   (	0x1,		0,		generic			),	\
>+
>+/*
>+ * Common CPUID leaves
>+ *
>+ * These leaves can be parsed once basic x86 vendor detection is in place.
>+ * Further vendor-agnostic leaves, which are not needed at early boot, are also
>+ * listed here.
>+ *
>+ * For vendor-specific leaves, a matching entry must be added to the CPUID leaf
>+ * vendor table later defined.  Leaves which are here, but without a matching
>+ * vendor entry, are treated by the CPUID parser as valid for all x86 vendors.
>+ */
>+#define CPUID_COMMON_ENTRIES									\
>+	/*			Leaf		Subleaf		Reader function */		\
> 	CPUID_PARSE_ENTRY   (	0x80000000,	0,		0x80000000		),	\
> 	CPUID_PARSE_ENTRY   (	0x80000002,	0,		generic			),	\
> 	CPUID_PARSE_ENTRY   (	0x80000003,	0,		generic			),	\
> 	CPUID_PARSE_ENTRY   (	0x80000004,	0,		generic			),	\

Isn't the general kernel coding style to put these multiline defines in curly
brackets? Then they're not needed when assigning the macro to a variable:

	-static const struct cpuid_parse_entry cpuid_parse_entries[] = {
	-	CPUID_PARSE_ENTRIES
	+static const struct cpuid_parse_entry cpuid_early_entries[] = CPUID_EARLY_ENTRIES

...
>+#define CPUID_VENDOR_ENTRY(_leaf, ...)							\
>+	{										\
>+		.leaf		= _leaf,						\
>+		.vendors	= { __VA_ARGS__ },					\
>+		.nvendors	= (sizeof((u8[]){__VA_ARGS__})/sizeof(u8)),		\
>+	}
>+
>+#define CPUID_VENDOR_ENTRIES								\
>+	/*		   Leaf		Vendor list		    */			\
>+
> #endif /* _ARCH_X86_CPUID_PARSER_H */

Same here?

-- 
Kind regards
Maciej Wieczór-Retman