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Date: Wed, 25 Apr 2018 19:25:02 +0200
From: Borislav Petkov <bp@suse.de>
Subject: [MODERATED] Re: [PATCH v4 06/10] [PATCH v4 6/9] Linux Patch #6
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To: speck@linutronix.de
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On Wed, Apr 25, 2018 at 11:32:23AM -0400, speck for Konrad Rzeszutek Wilk wro=
te:
> We need two CPU bit flags. First to say:
>=20
>  1). I am able to mitigate. This will be via X86_FEATURE_RDS for both
>     AMD and Intel.
>=20
>  2). I _want_ to mitigate. This will be via X86_FEATURE_SPEC_STORE_BYPASS_D=
ISABLE
>    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.

--=20
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imend=C3=B6rffer, Jane Smithard, Graham Norton, HR=
B 21284 (AG N=C3=BCrnberg)
--=20