[MODERATED] Re: [PATCH v4 06/10] [PATCH v4 6/9] Linux Patch #6

[Borislav Petkov <bp@suse.de>]

On Wed, Apr 25, 2018 at 11:32:23AM -0400, speck for Konrad Rzeszutek Wilk wrote:
> We need two CPU bit flags. First to say:
> 
>  1). I am able to mitigate. This will be via X86_FEATURE_RDS for both
>     AMD and Intel.
> 
>  2). I _want_ to mitigate. This will be via X86_FEATURE_SPEC_STORE_BYPASS_DISABLE
>    to tell the init_amd_bd,init_amd_zn,init_amd_jg, and init_intel
>    to do its magic.

Lemme paste from my earlier mail:

"
X86_BUG_SPEC_STORE_BYPASS               - CPU is affected by bug
X86_FEATURE_SPEC_STORE_BYPASS_DISABLE   - CPU can disable store bypassing
X86_FEATURE_SPEC_STORE_BYPASS_IN_USE    - CPU has disabled store bypassing
"

So I meant to use X86_FEATURE_SPEC_STORE_BYPASS_DISABLE for "I am able
to mitigate".

You want to use it to denote "IN_USE". I think "IN_USE" is more telling:

	if (... X86_FEATURE_SPEC_STORE_BYPASS_IN_USE)
		disable MD

So we can do

X86_BUG_SPEC_STORE_BYPASS
X86_FEATURE_RDS
X86_FEATURE_SPEC_STORE_BYPASS_IN_USE

or

X86_BUG_SPEC_STORE_BYPASS
X86_FEATURE_RDS
X86_FEATURE_SPEC_STORE_BYPASS_DISABLE

as you want it.

Whatever - I'm all out of energy for bikeshedding so pick one and
document what it means.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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