linux-kernel - Re: [PATCH 25/62] x86/head/64: Install boot GDT

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Message-ID: <20200212122052.GF20066@8bytes.org>
Date:   Wed, 12 Feb 2020 13:20:52 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 25/62] x86/head/64: Install boot GDT

On Tue, Feb 11, 2020 at 02:29:24PM -0800, Andy Lutomirski wrote:
> On Tue, Feb 11, 2020 at 5:53 AM Joerg Roedel <joro@...tes.org> wrote:
> > +       /* GDT loaded - switch to __KERNEL_CS so IRET works reliably */
> > +       pushq   $__KERNEL_CS
> > +       leaq    .Lon_kernel_cs(%rip), %rax
> > +       pushq   %rax
> > +       lretq
> > +
> > +.Lon_kernel_cs:
> > +       UNWIND_HINT_EMPTY
> 
> I would suggest fixing at least SS as well.

You are right, that is cleaner. Initialized DS, ES, and SS to
__KERNEL_DS here too.

Regards,

	Joerg