linux-kernel - Re: [PATCH v9 01/24] virt: sev-guest: Use AES GCM crypto library

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Message-ID: <20240612171710.GDZmnYFizmJoS5nMS1@fat_crate.local>
Date: Wed, 12 Jun 2024 19:17:10 +0200
From: Borislav Petkov <bp@...en8.de>
To: Nikunj A Dadhania <nikunj@....com>
Cc: linux-kernel@...r.kernel.org, thomas.lendacky@....com, x86@...nel.org,
	kvm@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
	dave.hansen@...ux.intel.com, pgonda@...gle.com, seanjc@...gle.com,
	pbonzini@...hat.com
Subject: Re: [PATCH v9 01/24] virt: sev-guest: Use AES GCM crypto library

On Fri, May 31, 2024 at 10:00:15AM +0530, Nikunj A Dadhania wrote:
> The sev-guest driver encryption code uses Crypto API for SNP guest
> messaging to interact with AMD Security processor. For enabling SecureTSC,
> SEV-SNP guests need to send a TSC_INFO request guest message before the
> smpboot phase starts. Details from the TSC_INFO response will be used to
> program the VMSA before the secondary CPUs are brought up. The Crypto API
> is not available this early in the boot phase.
> 
> In preparation of moving the encryption code out of sev-guest driver to
> support SecureTSC and make reviewing the diff easier, start using AES GCM
> library implementation instead of Crypto API.
> 
> Drop __enc_payload() and dec_payload() helpers as both are pretty small and
> can be moved to the respective callers.

Please use this streamlined commit message for your next submission:

"The sev-guest driver encryption code uses the crypto API for SNP guest messaging
with the AMD Security processor. In order to enable secure TSC, SEV-SNP guests
need to send such a TSC_INFO message before the APs are booted. Details from the 
TSC_INFO response will then be used to program the VMSA before the APs are 
brought up.

However, the crypto API is not available this early in the boot process.

In preparation for moving the encryption code out of sev-guest to support secure
TSC and to ease review, switch to using the AES GCM library implementation
instead.

Drop __enc_payload() and dec_payload() helpers as both are small and can be
moved to the respective callers."

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette