linux-kernel - Re: [PATCH v6 1/2] x86/sev: Make sure IRQs are disabled while GHCB is active

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Date:   Fri, 18 Jun 2021 10:25:06 +0200
From:   Joerg Roedel <jroedel@...e.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Joerg Roedel <joro@...tes.org>, x86@...nel.org, hpa@...or.com,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        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 v6 1/2] x86/sev: Make sure IRQs are disabled while GHCB
 is active

On Thu, Jun 17, 2021 at 05:00:48PM +0200, Peter Zijlstra wrote:
> I think this is broken, at this point RCU is quite dead on this CPU and
> local_irq_save/restore include tracing and all sorts.
> 
> Also, shouldn't IRQs already be disabled by the time we get here?

Yes it is, I removed these calls, made __sev_get/put_ghcb() noinstr
instead of __always_inline and put instrumentation_begin()/end() around
the panic() call in __sev_get_ghcb().

Regards,

	Joerg