Re: [PATCH V2 03/14] x86/set_memory: Add x86_set_memory_enc static call support

Tianyu Lan
2021-08-05T15:52:04Z

On 8/5/2021 10:29 PM, Dave Hansen wrote:
> On 8/5/21 7:23 AM, Peter Zijlstra wrote:
>> This is assuming any of this is actually performance critical, based off
>> of this using static_call() to begin with.
>
> This code is not performance critical.
>
> I think I sent folks off on a wild goose chase when I asked that we make
> an effort to optimize code that does:
>
> if (some_hyperv_check())
> foo();
>
> if (some_amd_feature_check())
> bar();
>
> with checks that will actually compile away when Hyper-V or
> some_amd_feature() is disabled. That's less about performance and just
> about good hygiene. I *wanted* to see
> cpu_feature_enabled(X86_FEATURE...) checks.
>
> Someone suggested using static calls, and off we went...
>
> Could we please just use cpu_feature_enabled()?
>

Yes, cpu_feature_enabled() works. The target is just to run platform
code after platform check. I will update this in the next version.