linux-kernel - Re: [PATCH v1 04/26] x86/sev: Add the host SEV-SNP initialization support

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Date: Mon, 8 Jan 2024 18:04:18 +0100
From: Borislav Petkov <bp@...en8.de>
To: Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>
Cc: Michael Roth <michael.roth@....com>, x86@...nel.org,
	kvm@...r.kernel.org, linux-coco@...ts.linux.dev, linux-mm@...ck.org,
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, mingo@...hat.com, jroedel@...e.de,
	thomas.lendacky@....com, hpa@...or.com, ardb@...nel.org,
	pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
	jmattson@...gle.com, luto@...nel.org, dave.hansen@...ux.intel.com,
	slp@...hat.com, pgonda@...gle.com, peterz@...radead.org,
	srinivas.pandruvada@...ux.intel.com, rientjes@...gle.com,
	tobin@....com, vbabka@...e.cz, kirill@...temov.name,
	ak@...ux.intel.com, tony.luck@...el.com,
	sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
	jarkko@...nel.org, ashish.kalra@....com, nikunj.dadhania@....com,
	pankaj.gupta@....com, liam.merwick@...cle.com, zhi.a.wang@...el.com,
	Brijesh Singh <brijesh.singh@....com>
Subject: Re: [PATCH v1 04/26] x86/sev: Add the host SEV-SNP initialization
 support

On Mon, Jan 08, 2024 at 05:49:01PM +0100, Jeremi Piotrowski wrote:
> What I wrote: "allow for the kernel to allocate the rmptable".

What?!

"15.36.5 Hypervisor RMP Management

...

Because the RMP is initialized by the AMD-SP to prevent direct access to
the RMP, the hypervisor must use the RMPUPDATE instruction to alter the
entries of the RMP. RMPUPDATE allows the hypervisor to alter the
Guest_Physical_Address, Assigned, Page_Size, Immutable, and ASID fields
of an RMP entry."

What you want is something that you should keep far and away from the
upstream kernel.

-- 
Regards/Gruss,
    Boris.

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