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Subject: Re: [RFC v2 01/32] x86/paravirt: Introduce CONFIG_PARAVIRT_XL
To:     Borislav Petkov <bp@alien8.de>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
        Raj Ashok <ashok.raj@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        linux-kernel@vger.kernel.org
References: <cover.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com>
 <4f8c9559dd04d8e8485c419c5ebc9471613f7928.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com>
 <YIhKXcNuinL0ar0O@zn.tnic>
From:   Juergen Gross <jgross@suse.com>
Message-ID: <f62354fe-e202-ad38-5466-03e79954f757@suse.com>
Date:   Mon, 10 May 2021 10:07:53 +0200
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From: Juergen Gross <jgross@suse.com>
To: Borislav Petkov <bp@alien8.de>,
 Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Andy Lutomirski <luto@kernel.org>,
 Dave Hansen <dave.hansen@intel.com>, Dan Williams
 <dan.j.williams@intel.com>, Tony Luck <tony.luck@intel.com>,
 Andi Kleen <ak@linux.intel.com>,
 Kirill Shutemov <kirill.shutemov@linux.intel.com>,
 Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
 Raj Ashok <ashok.raj@intel.com>, Sean Christopherson <seanjc@google.com>,
 linux-kernel@vger.kernel.org
Message-ID: <f62354fe-e202-ad38-5466-03e79954f757@suse.com>
Subject: Re: [RFC v2 01/32] x86/paravirt: Introduce CONFIG_PARAVIRT_XL
References: <cover.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com>
 <4f8c9559dd04d8e8485c419c5ebc9471613f7928.1619458733.git.sathyanarayanan.kuppuswamy@linux.intel.com>
 <YIhKXcNuinL0ar0O@zn.tnic>
In-Reply-To: <YIhKXcNuinL0ar0O@zn.tnic>

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On 27.04.21 19:31, Borislav Petkov wrote:
> + J=C3=BCrgen.
>=20
> On Mon, Apr 26, 2021 at 11:01:28AM -0700, Kuppuswamy Sathyanarayanan wr=
ote:
>> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>>
>> Split off halt paravirt calls from CONFIG_PARAVIRT_XXL into
>> a separate config option. It provides a middle ground for
>> not-so-deep paravirtulized environments.
>=20
> Please introduce a spellchecker into your patch creation workflow.
>=20
> Also, what does "not-so-deep" mean?
>=20
>> CONFIG_PARAVIRT_XL will be used by TDX that needs couple of paravirt
>> calls that were hidden under CONFIG_PARAVIRT_XXL, but the rest of the
>> config would be a bloat for TDX.
>=20
> Used how? Why is it bloat for TDX?

Is there any major downside to move the halt related pvops functions
from CONFIG_PARAVIRT_XXL to CONFIG_PARAVIRT?

I'd rather introduce a new PARAVIRT level only in case of multiple
pvops functions needed for a new guest type, or if a real hot path
would be affected.


Juergen

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