linux-kernel - Re: [Question PATCH kernel] x86/amd/sev/nmi+vc: Fix stack handling (why is this happening?)

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Message-ID: <Y9OpcoSacyOkPkvl@8bytes.org>
Date:   Fri, 27 Jan 2023 11:37:38 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Alexey Kardashevskiy <aik@....com>, kvm@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Jiri Kosina <jkosina@...e.cz>, Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [Question PATCH kernel] x86/amd/sev/nmi+vc: Fix stack handling
 (why is this happening?)

On Fri, Jan 27, 2023 at 10:08:14AM +0100, Peter Zijlstra wrote:
> Welcome to the wonderful shit show that is x86 exceptions :/
> 
> I thought sev_es_*() is supposed to fix this. Joerg, any clue?

Hmm, no, not yet, the stack-trace doesn't make much sense to me. The
sev_es_* function calls in the NMI path are for re-enabling NMI and
adjusting the #VC IST stack to allow nested VCs.

Alexey, can you try to get a more stable backtrace? For example by
building the kernel with frame pointers?

Regards,

	Joerg