linux-kernel - Re: [PATCH] clarify how insecure CPU is

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Message-ID: <20180108230355.GA25349@amd>
Date:   Tue, 9 Jan 2018 00:03:55 +0100
From:   Pavel Machek <pavel@....cz>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, r.marek@...embler.cz,
        ricardo.neri-calderon@...ux.intel.com, rkrcmar@...hat.com,
        Janakarajan.Natarajan@....com, bp@...e.de, x86@...nel.org,
        hpa@...or.com, mingo@...hat.com,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] clarify how insecure CPU is

On Mon 2018-01-08 21:27:25, Thomas Gleixner wrote:
> On Mon, 8 Jan 2018, Pavel Machek wrote:
> 
> > 
> > First, what is going on with X86_BUG_AMD_E400 and X86_BUG_AMD_APIC_C1E
> > ? They seem to refer to the same bug, perhaps comment should mention
> > that? (Do we need two flags for one bug?)
> > 
> > Next, maybe X86_BUG_CPU_INSECURE is a bit too generic? This seems to
> > address "Meltdown" problem, but not "Spectre". Should it be limited to
> > PPro and newer Intel CPUs?
> > 
> > Should another erratum be added for "Spectre"? This is present even on
> > AMD CPUs, but should not be present in 486, maybe Pentium, and some
> > Atom chips?
> > 
> > Plus... is this reasonable interface?
> > 
> > bugs		: cpu_insecure
> 
> We've renamed it to meltdown already and added spectre_v1/v2 bits for the
> rest of the mess.

Could you explain (best with code comment) what is going on with
X86_BUG_AMD_E400 and X86_BUG_AMD_APIC_C1E ? They seem to refer to the
same bug.

Plus, as I explained: "bugs: meltdown, spectre" seems to be bad idea,
as userland application can not easily tell between "no bug" and "bug
not known to kernel".

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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