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From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>
Subject: [PATCH v10 043/108] KVM: x86/mmu: Require TDP MMU for TDX
Date:   Sat, 29 Oct 2022 23:22:44 -0700
Message-Id: <82c25eec5a4c42e4b6a2038c7553bbaf56e87091.1667110240.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

Require the TDP MMU for guest TDs, the so called "shadow" MMU does not
support mapping guest private memory, i.e. does not support Secure-EPT.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index c6be76f9849c..1bf58288ea79 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -18,8 +18,12 @@ int kvm_mmu_init_tdp_mmu(struct kvm *kvm)
 {
 	struct workqueue_struct *wq;
 
+	/*
+	 * Because only the TDP MMU supports TDX, require the TDP MMU for guest
+	 * TDs.
+	 */
 	if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled))
-		return 0;
+		return kvm->arch.vm_type == KVM_X86_TDX_VM ? -EOPNOTSUPP : 0;
 
 	wq = alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0);
 	if (!wq)
-- 
2.25.1