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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3ae51aac-085a-44f6-9f6f-565c7c5687ad@intel.com>
Date: Tue, 15 Oct 2024 06:14:29 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Jürgen Groß <jgross@...e.com>,
 "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 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>
Cc: 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 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.