Re: [PATCH 4/5] x86/cpuid: Standardize on u32 in <asm/cpuid/api.h>

[Xin Li]

On 3/17/2025 3:18 PM, Ingo Molnar wrote:
> Convert all uses of 'unsigned int' to 'u32' in <asm/cpuid/api.h>.
>
> This is how a lot of the call sites are doing it, and the two
> types are equivalent in the C sense - but 'u32' better expresses
> that these are expressions of an immutable hardware ABI.
>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Ahmed S. Darwish <darwi@xxxxxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
> Cc: x86-cpuid@xxxxxxxxxxxxxxx
> Link: https://lore.kernel.org/r/20250317164745.4754-3-darwi@xxxxxxxxxxxxx
> ---
>   arch/x86/include/asm/cpuid/api.h | 40 ++++++++++++++++++++--------------------
>   1 file changed, 20 insertions(+), 20 deletions(-)
>
> diff --git a/arch/x86/include/asm/cpuid/api.h b/arch/x86/include/asm/cpuid/api.h
> index f26926ba5289..356db1894588 100644
> --- a/arch/x86/include/asm/cpuid/api.h
> +++ b/arch/x86/include/asm/cpuid/api.h
> @@ -22,8 +22,8 @@ static inline bool have_cpuid_p(void)
>   }
>   #endif
>   
> -static inline void native_cpuid(unsigned int *eax, unsigned int *ebx,
> -				unsigned int *ecx, unsigned int *edx)
> +static inline void native_cpuid(u32 *eax, u32 *ebx,
> +				u32 *ecx, u32 *edx)
>   {
>   	/* ecx is often an input as well as an output. */
>   	asm volatile("cpuid"
> @@ -36,9 +36,9 @@ static inline void native_cpuid(unsigned int *eax, unsigned int *ebx,
>   }
>   
>   #define NATIVE_CPUID_REG(reg)					\
> -static inline unsigned int native_cpuid_##reg(unsigned int op)	\
> +static inline u32 native_cpuid_##reg(u32 op)	\
>   {								\
> -	unsigned int eax = op, ebx, ecx = 0, edx;		\
> +	u32 eax = op, ebx, ecx = 0, edx;		\
>   								\
>   	native_cpuid(&eax, &ebx, &ecx, &edx);			\
>   								\
> @@ -65,9 +65,9 @@ NATIVE_CPUID_REG(edx)
>    * Clear ECX since some CPUs (Cyrix MII) do not set or clear ECX
>    * resulting in stale register contents being returned.
>    */
> -static inline void cpuid(unsigned int op,
> -			 unsigned int *eax, unsigned int *ebx,
> -			 unsigned int *ecx, unsigned int *edx)
> +static inline void cpuid(u32 op,
> +			 u32 *eax, u32 *ebx,
> +			 u32 *ecx, u32 *edx)
>   {
>   	*eax = op;
>   	*ecx = 0;
> @@ -75,9 +75,9 @@ static inline void cpuid(unsigned int op,
>   }
>   
>   /* Some CPUID calls want 'count' to be placed in ECX */
> -static inline void cpuid_count(unsigned int op, int count,
> -			       unsigned int *eax, unsigned int *ebx,
> -			       unsigned int *ecx, unsigned int *edx)
> +static inline void cpuid_count(u32 op, int count,
> +			       u32 *eax, u32 *ebx,
> +			       u32 *ecx, u32 *edx)
>   {
>   	*eax = op;
>   	*ecx = count;
> @@ -88,43 +88,43 @@ static inline void cpuid_count(unsigned int op, int count,
>    * CPUID functions returning a single datum:
>    */
>   
> -static inline unsigned int cpuid_eax(unsigned int op)
> +static inline u32 cpuid_eax(u32 op)
>   {
> -	unsigned int eax, ebx, ecx, edx;
> +	u32 eax, ebx, ecx, edx;
>   
>   	cpuid(op, &eax, &ebx, &ecx, &edx);
>   
>   	return eax;
>   }
>   
> -static inline unsigned int cpuid_ebx(unsigned int op)
> +static inline u32 cpuid_ebx(u32 op)
>   {
> -	unsigned int eax, ebx, ecx, edx;
> +	u32 eax, ebx, ecx, edx;
>   
>   	cpuid(op, &eax, &ebx, &ecx, &edx);
>   
>   	return ebx;
>   }
>   
> -static inline unsigned int cpuid_ecx(unsigned int op)
> +static inline u32 cpuid_ecx(u32 op)
>   {
> -	unsigned int eax, ebx, ecx, edx;
> +	u32 eax, ebx, ecx, edx;
>   
>   	cpuid(op, &eax, &ebx, &ecx, &edx);
>   
>   	return ecx;
>   }
>   
> -static inline unsigned int cpuid_edx(unsigned int op)
> +static inline u32 cpuid_edx(u32 op)
>   {
> -	unsigned int eax, ebx, ecx, edx;
> +	u32 eax, ebx, ecx, edx;
>   
>   	cpuid(op, &eax, &ebx, &ecx, &edx);
>   
>   	return edx;
>   }
>   
> -static inline void __cpuid_read(unsigned int leaf, unsigned int subleaf, u32 *regs)
> +static inline void __cpuid_read(u32 leaf, u32 subleaf, u32 *regs)
>   {
>   	regs[CPUID_EAX] = leaf;
>   	regs[CPUID_ECX] = subleaf;
> @@ -141,7 +141,7 @@ static inline void __cpuid_read(unsigned int leaf, unsigned int subleaf, u32 *re
>   	__cpuid_read(leaf, 0, (u32 *)(regs));		\
>   }
>   
> -static inline void __cpuid_read_reg(unsigned int leaf, unsigned int subleaf,
> +static inline void __cpuid_read_reg(u32 leaf, u32 subleaf,
>   				    enum cpuid_regs_idx regidx, u32 *reg)
>   {
>   	u32 regs[4];

A nice move to set the standard.

When refactoring the MSR code, I also converted all unsigned int to u32.

Reviewed-by: Xin Li (Intel) <xin@xxxxxxxxx>