Re: [patch V4 02/41] cpu/SMT: Make SMT control more robust against enumeration failures

[Dave Hansen]

On 8/14/23 01:53, Thomas Gleixner wrote:
> -static inline bool cpu_smt_allowed(unsigned int cpu)
> +static inline bool cpu_bootable(unsigned int cpu)
>  {
>  	if (cpu_smt_control == CPU_SMT_ENABLED)
>  		return true;
>  
> +	if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
> +		return true;

I found this new pair of if()'s rather counterintuitive to read.

The first one reads like:

	"If SMT is not supported, the CPU is always bootable"

but "supported" could easily mean CONFIG_SMP==n (which is actually
covered in the next case).  Would this be better named:

	CPU_SMT_NOT_ENUMERATED
or
	CPU_SMT_NOT_DETECTED

?

	/* Every CPU is bootable on non-SMT systems: */
	if (cpu_smt_control == CPU_SMT_NOT_DETECTED)
		return true;

For the next one:

> +	if (cpu_smt_control == CPU_SMT_NOT_IMPLEMENTED)
> +		return true;

This reads a bit like "SMT is not implemented" rather than "SMT controls
are not implemented".  Maybe a comment would help:

	/* All CPUs are bootable if controls are not implemented: */