linux-kernel - Re: [PATCH v5 2/6] x86/sev-es: Make sure IRQs are disabled while GHCB is active

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Message-ID: <YMh06KmGITjU4eAf@8bytes.org>
Date:   Tue, 15 Jun 2021 11:37:44 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, Joerg Roedel <jroedel@...e.de>, hpa@...or.com,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Martin Radev <martin.b.radev@...il.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v5 2/6] x86/sev-es: Make sure IRQs are disabled while
 GHCB is active

On Mon, Jun 14, 2021 at 06:25:18PM +0200, Borislav Petkov wrote:
> Thoughts?

Okay, I tested a bit with this, it mostly works fine.

The lockdep_hardirqs_disabled() check in __sev_get/put_ghcb() was
problematic, because these functions are called also when no state is
set up yet. More specifically it is called from __sev_es_nmi_complete(),
which is called at the very beginning of do_nmi(), before the NMI
handler entered NMI mode. So this triggered a warning in the NMI
test-suite when booting up, I replaced these checks with a
WARN_ON(!irqs_disabled()) and also removed the BUG_ON()s.

With that it boots fine and without SEV-ES related warnings.

Regards,

	Joerg