linux-kernel - Re: [PATCHv2 16/29] x86/boot: Add a trampoline for booting APs via firmware handoff

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Message-ID: <20220216141009.ymmjduf5doqnhnqy@black.fi.intel.com>
Date:   Wed, 16 Feb 2022 17:10:09 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        tglx@...utronix.de, mingo@...hat.com, dave.hansen@...el.com,
        luto@...nel.org, peterz@...radead.org, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Kai Huang <kai.huang@...el.com>
Subject: Re: [PATCHv2 16/29] x86/boot: Add a trampoline for booting APs via
 firmware handoff

On Wed, Feb 16, 2022 at 11:07:15AM +0100, Borislav Petkov wrote:
> On Wed, Feb 16, 2022 at 12:36:24AM +0300, Kirill A. Shutemov wrote:
> > How can signle trampoline_start cover all cases?
> 
> All I'm saying is that the real mode header should have a single
> 
> 	u32     trampoline_start;
> 
> instead of:
> 
> 	u32     trampoline_start;
> 	u32     sev_es_trampoline_start;
> 	u32     trampoline_start64;
> 
> which all are the same thing on a single system.

But these are generated at build time, no?

As far as I can see it is initialized in arch/x86/realmode/rm/header.S by
linker.

I'm confused.

-- 
 Kirill A. Shutemov