linux-kernel - Re: efi boot failures due to PTI with 32 bit builds and Intel CPUs

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Message-ID: <CA+55aFzQwC59pkeA+T3E0G4SZe4dQsYcmnf1eKGYnYpcPTKhSQ@mail.gmail.com>
Date:   Thu, 30 Aug 2018 11:21:49 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Michal Hocko <mhocko@...e.com>,
        Andi Kleen <ak@...ux.intel.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Pavel Machek <pavel@....cz>
Subject: Re: efi boot failures due to PTI with 32 bit builds and Intel CPUs

On Thu, Aug 30, 2018 at 11:08 AM Joerg Roedel <jroedel@...e.de> wrote:
>
> Without a mapped GDT the #PF and #DF handlers also can't be started, so
> the machine triple-faults. Below diff fixes it for me, I'll send a
> proper patch tomorrow.

Hmm. Is there any reason why this code doesn't just use

        load_fixmap_gdt(0);

and shouldn't it do it after loading the new %cr3?

               Linus