linux-kernel - Re: [PATCH v3 0/8] Support ACPI PSP on Hyper-V

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20230322181541.GEZBtFzRAMcH9BAzUe@fat_crate.local>
Date:   Wed, 22 Mar 2023 19:15:41 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
Cc:     linux-kernel@...r.kernel.org,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        "Kalra, Ashish" <ashish.kalra@....com>,
        linux-crypto@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Subject: Re: [PATCH v3 0/8] Support ACPI PSP on Hyper-V

On Wed, Mar 22, 2023 at 06:33:37PM +0100, Jeremi Piotrowski wrote:
> What this does is it allows a normal (non-SNP) VM to host confidential (SNP)
> VMs. I say "normal" but not every VM is going to be able to do this, it needs

If you say "non-SNP" VM then this sounds like purely for development.
Because I cannot see how you're going to give the confidentiality
guarantee to the SNP guests if the lower level is unencrypted, non-SNP
and so on...

> to be running on AMD hardware and configured to have access to
> VirtualizationExtensions, a "HardwareIsolation" capability, and given a number
> of "hardware isolated guests" that it is allowed to spawn. In practice this
> will result in the VM seeing a PSP device, SEV-SNP related CPUID
> leafs, and have access to additional memory management instructions
> (rmpadjust/psmash).  This allows the rest of the of KVM-SNP support to
> work.

So why don't you emulate the PSP in KVM instead of doing some BIOS hack?
And multiplex the access to it between all the parties needing it?

-- 
Regards/Gruss,
    Boris.

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