linux-kernel - Re: kexec reboot fails with extra wbinvd introduced for AME SME

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Date:   Wed, 17 Jan 2018 12:10:49 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Dave Young <dyoung@...hat.com>
Cc:     Yu Chen <yu.c.chen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Juergen Gross <jgross@...e.com>,
        Tony Luck <tony.luck@...el.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Borislav Petkov <bp@...en8.de>,
        Rui Zhang <rui.zhang@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        Kexec Mailing List <kexec@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ebiederm@...hat.com, Tom Lendacky <thomas.lendacky@....com>,
        Baoquan He <bhe@...hat.com>
Subject: Re: kexec reboot fails with extra wbinvd introduced for AME SME

On Wed, Jan 17, 2018 at 11:42 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
>  [ .. ]        Some of the errata
> around SME have been about machine check exceptions or something.

That should be "some of the errata around wbinvd". I have no idea if
there have been SME issues.

That said, the really bad old wbinvd bug (which hung the system iirc)
was for some old PPro CPU's. Googling around, the errata I find seem
either irrelevant (eip corruption in 16-bit mode) or fairly mild (odd
behavior wrt parity errors).

So I have this memory of wbinvd having problems, but that memory does
seem to be largely historical. But Dave Young clearly sees *something*
odd going on.

               Linus