linux-kernel - Re: [BUG net-next] arch/x86/kernel/cpu/bugs.c:2935: "Unpatched return thunk in use. This should not happen!" [STACKTRACE]

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Date: Wed, 20 Mar 2024 02:28:57 +0100
From: Mirsad Todorovac <mirsad.todorovac@....unizg.hr>
To: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org, Sean Christopherson <seanjc@...gle.com>,
 Paolo Bonzini <pbonzini@...hat.com>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
 Fuad Tabba <tabba@...gle.com>, Marc Zyngier <maz@...nel.org>,
 Shaoqin Huang <shahuang@...hat.com>, David Matlack <dmatlack@...gle.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 Peter Zijlstra <peterz@...radead.org>, Breno Leitao <leitao@...ian.org>,
 kvm@...r.kernel.org
Subject: Re: [BUG net-next] arch/x86/kernel/cpu/bugs.c:2935: "Unpatched return
 thunk in use. This should not happen!" [STACKTRACE]

On 3/18/24 21:21, Borislav Petkov wrote:
> On Mon, Mar 18, 2024 at 08:47:26PM +0100, Mirsad Todorovac wrote:
>> With the latest net-next v6.8-5204-g237bb5f7f7f5 kernel, while running kselftest, there was this
>> trap and stacktrace:
> 
> Send your kernel .config and how exactly you're triggering it, please.
> 
> Thx.

Hi,

Please find the kernel .config attached.

I got another one of these "Unpatched thunk" and it seems connected with selftest/kvm.

But running selftests/kvm one by one did not trigger the bug.

Best regards,
Mirsad Todorovac
Download attachment "config-6.8.0-net-next-km-05204-g237bb5f7f7f5-dirty.xz" of type "application/x-xz" (59464 bytes)

View attachment "unpatched-return-thunk-decoded-02.log" of type "text/x-log" (10573 bytes)