RE: [PATCH v12 01/37] x86/cpufeatures: Add the cpu feature bit for WRMSRNS

[Li, Xin3]

> and if you had to be precise, the code should do:
> 
> 	if (cpu_feature_enabled(X86_FEATURE_FRED)) {
> 		if (cpu_feature_enabled(X86_FEATURE_WRMSRNS))
> 			wrmsrns(MSR_IA32_FRED_RSP0, (unsigned
> long)task_stack_page(task) + THREAD_SIZE);
> 		else
> 			wrmsr(MSR_IA32_FRED_RSP0, (unsigned
> long)task_stack_page(task) + THREAD_SIZE);
> 	}

This is exactly what tglx wanted to avoid.

And I love the idea "baseline", especially we have a ton of CPU features.

> 
> > Another patch set should replace WRMSR with WRMSRNS, with SERIALIZE
> > added when needed.
> 
> I sense someone wants to optimize MSR writes ... :-)

:-)