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

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Date:   Tue, 9 Jan 2018 00:44:30 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Pavel Machek <pavel@....cz>
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 Tue, 9 Jan 2018, Pavel Machek wrote:

> 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.

Sorry, that;s really not the time for this.

> 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".

https://lkml.kernel.org/r/20180107214913.096657732@linutronix.de
https://lkml.kernel.org/r/20180107214913.177414879@linutronix.de

Thanks,

	tglx