linux-kernel - Re: [PATCH] x86/paravirt: Fix build PARAVIRT_XXL=y without XEN

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Message-ID: <0f0b9784-1902-1526-2796-7d1a7ab17fb6@intel.com>
Date:   Wed, 17 Nov 2021 11:57:15 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>
Cc:     "Kirill A. Shutemov" <kirill@...temov.name>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Juergen Gross <jgross@...e.com>, Deep Shah <sdeep@...are.com>,
        "VMware, Inc." <pv-drivers@...are.com>
Subject: Re: [PATCH] x86/paravirt: Fix build PARAVIRT_XXL=y without XEN_PV

> TDX has a requirement to use HLT paravirt calls (which is currently
> listed under PARAVIRT_XXL). Once we submit a patch to move it
> under CONFIG_PARAVIRT, we will drop this dependency.

Taking a step back...

The basic requirement here is murky.  Why does TDX need to use these
paravirt hooks in the first place?  Why does TDX have "a requirement to
use HLT paravirt calls"?

If it really is just about idle, perhaps Peter's suggestion warrants
investigation.  But, we need to know the root cause instead of simply
tossing around "requirements".