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Date: Wed, 17 Jun 2026 15:25:34 +0200
From: =?utf-8?B?SsO2cmcgUsO2ZGVs?= <joro@8bytes.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, x86@kernel.org, 
	Tom Lendacky <thomas.lendacky@amd.com>, Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org, 
	linux-kernel@vger.kernel.org, coconut-svsm@lists.linux.dev, 
	Joerg Roedel <joerg.roedel@amd.com>, Jethro Beekman <jethro@fortanix.com>
Subject: Re: [PATCH 4/4] kvm: svm: Support KVM_SEV_SNP_PAGE_TYPE_VMSA at
 SNP_LAUNCH_UPDATE
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On Wed, Jun 17, 2026 at 06:00:39AM -0700, Sean Christopherson wrote:
> On Wed, Jun 17, 2026, Jörg Rödel wrote:
> > With the current code KVM will create its own VMSA for each created VCPU and
> > measure it into the guests initial image. This makes predicting the initial
> > launch measurement difficult (as it depends on KVM internals) and fragile because
> > KVM-internal changes always carry a risk to change the launch measurement
> 
> The same holds true for userspace.

Right, but if user-space breaks the launch measurement it must be a problem in
the IGVM loader, as the IGVM-file contains all necessary state from which the
launch measurement can be derived, including the initial VMSA for the BSP.

> > (which has happened a couple of times already).
> 
> Examples?  The SEV features thing jumps to mind, but I don't recall any others
> off the top of my head.

I was referring to KVM-induced changes to SEV features, but thought this
happened more than once?


-Joerg