linux-kernel - Re: Hang when booting guest kernels compiled with clang after SRSO mitigations

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Message-ID: <20230811161225.GIZNZd6QfLUoZv9TLO@fat_crate.local>
Date:   Fri, 11 Aug 2023 18:12:25 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Nathan Chancellor <nathan@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: Hang when booting guest kernels compiled with clang after SRSO
 mitigations

On Fri, Aug 11, 2023 at 09:03:18AM -0700, Sean Christopherson wrote:
> Might be the flags bug that borks KVM's fastop() emulation.  If that fixes things,
> my guess is that bringing APs out of WFS somehow triggers emulation.

I was just about to connect you two guys, thanks Sean!

> https://lore.kernel.org/all/20230811155255.250835-1-seanjc@google.com

Nathan, if you could test, that would be cool.

Also, Nick has another patch for -mno-shared, it probably isn't fixing
yours but it would be good to test it too, just in case:

https://github.com/ClangBuiltLinux/linux/issues/1911#issuecomment-1674993796

Thx!

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette