Re: [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature

[Dave Hansen]

On 01/05/2018 06:12 PM, Tim Chen wrote:
>  .macro ENABLE_IBRS
> -	ALTERNATIVE "jmp .Lskip_\@", "", X86_FEATURE_SPEC_CTRL
> +	testl	$1, dynamic_ibrs
> +	jz	.Lskip_\@

There was an earlier suggestion to use STATIC_JUMP_IF_... here.  That's
a good suggestion, but we encountered some issues with it either
crashing the kernel at boot or not properly turning on/off.

We would love to do that minor really soon, but we figured everyone
would rather see this version than wait for us to debug such a minor tweak.