linux-kernel - Re: [PATCH v3 70/75] x86/head/64: Setup TSS early for secondary CPUs

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Message-ID: <20200602154611.GC11634@zn.tnic>
Date:   Tue, 2 Jun 2020 17:46:11 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        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>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Joerg Roedel <jroedel@...e.de>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v3 70/75] x86/head/64: Setup TSS early for secondary CPUs

On Tue, Apr 28, 2020 at 05:17:20PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> The #VC exception will trigger very early in head_64.S, when the first
> CPUID instruction is executed. When secondary CPUs boot, they already
> load the real system IDT, which has the #VC handler configured to be
> using an IST stack. IST stacks require a TSS to be loaded, to set up the
> TSS early for bringing up the secondary CPUs. Use the RW version of
> early, until cpu_init() switches to the RO mapping.

I think you wanna say "Use the read-write version of the per-CPU TSS struct
early." here.

-- 
Regards/Gruss,
    Boris.

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