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Date: Fri, 20 Apr 2018 19:42:42 +0200
From: Borislav Petkov <bp@suse.de>
Subject: [MODERATED] Re: [patch 07/11] [PATCH v2 07/10] Linux Patch #7
Message-ID: <20180420174242.GO13977@pd.tnic>
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To: speck@linutronix.de
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On Thu, Apr 19, 2018 at 10:25:47PM -0400, speck for konrad.wilk_at_oracle.com=
 wrote:
> x86/cpu: Add fix_this_cpu to be called _after_ check_bugs and at BSP.
>=20
> We do a lot of things in the check_bugs() - one of the first
> things we do is identify_boot_cpu() which calls identify_cpu()
> which calls this_cpu->init.
>=20
> Once identify_boot_cpu() is done _then_ it walks through the
> spectre_v2_select_mitigation() and alternative_assembler().
>=20
> If there are some CPU fix ups _after_ spectre_v2 is done
> we can't activate those on the BSP as we have already
> called 'this_cpu->init'. Hence add a new function to
> fixup CPUs.

Konrad, this is still unnecessary and adding superfluous complexity to
an already crazy early boot path. Let me clarify the flow:

First you are on the BSP:

setup_arch()
|-> early_cpu_init
|-> early_identify_cpu
|-> cpu_set_bug_bits

now you have all the X86_BUG bits set so that you can test them in the
functions later.

Then, you're still on the BSP and can do check_bugs() with all cmdline
options picking apart etc etc.

setup_arch()
|-> check_bugs()
|-> ssb_select_mitigation()
|-> identify_boot_cpu()			<--- HERE you call ->c_init() on the BSP
|-> spectre_v2_select_mitigation

In that order!

So, all you wanna do works without adding this new function pointer.

--=20
Regards/Gruss,
    Boris.

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