linux-kernel - Re: [PATCH] x86/kvm: Override default caching mode for SEV-SNP and TDX

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Message-ID: <87da3d70-5906-4778-bba9-c5df26ae8e02@suse.com>
Date: Tue, 15 Oct 2024 16:00:18 +0200
From: Juergen Gross <jgross@...e.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Dave Hansen <dave.hansen@...el.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
 Vitaly Kuznetsov <vkuznets@...hat.com>, Thomas Gleixner
 <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, Binbin Wu <binbin.wu@...el.com>,
 Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [PATCH] x86/kvm: Override default caching mode for SEV-SNP and
 TDX

On 15.10.24 15:54, Kirill A. Shutemov wrote:
> On Tue, Oct 15, 2024 at 06:14:29AM -0700, Dave Hansen wrote:
>> On 10/15/24 03:12, Jürgen Groß wrote:
>>>>
>>>> +    /* Set WB as the default cache mode for SEV-SNP and TDX */
>>>> +    mtrr_overwrite_state(NULL, 0, MTRR_TYPE_WRBACK);
>>>
>>> Do you really want to do this for _all_ KVM guests?
>>>
>>> I'd expect this call to be conditional on TDX or SEV-SNP.
>>
>> I was confused by this as well.
>>
>> Shouldn't mtrr_overwrite_state() be named something more like:
>>
>> 	guest_force_mtrr_state()
>>
>> or something?
>>
>> The mtrr_overwrite_state() comment is pretty good, but it looks quite
>> confusing from the caller.
> 
> I can submit a following up patch with rename if it is fine.
> 

Fine with me.

Juergen

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