KVM: VMX: Use kvm_mmu_page role to construct EPTP, not current vCPU state

KVM: VMX: Use kvm_mmu_page role to construct EPTP, not current vCPU state

Use the role for the to-be-loaded/invalidated EPT root to compute the
root's level and A/D enablement instead of pulling the information from
the vCPU (e.g. by passing in the root level and querying vmcs12).  Not
making unnecessary assumptions about the root will allow invalidating
arbitrary EPT roots (which sadly requires a full EPTP) at any given time.

No functional change intended (the end result should be the same).

Link: https://lore.kernel.org/r/20250919005955.1366256-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>