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No way is KVM going to rely on userspace to opt-in to > preventing the guest from enabling features. > 2: Backwards compatilibity if KVM unconditionally enforces ALLOWED_SEV_FEATURES. > Although maybe there's nothing to do here? I vaguely recall all of the gated > features being unsupported, or something... This contradicts your review comment from the previous version of the series [1]. If KVM enforces ALLOWED_SEV_FEATURES, it can break existing VMs, thus the explicit userspace allowed-sev-features=on opt-in [2]. Thanks, Kim [1] https://lore.kernel.org/kvm/ZsfKYHFkWA-Rh23C@google.com/ [2] https://lore.kernel.org/kvm/20250207233327.130770-1-kim.phillips@amd.com/