linux-kernel - [RFC PATCH v5 058/104] KVM: x86/mmu: Focibly use TDP MMU for TDX

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Date:   Fri,  4 Mar 2022 11:49:14 -0800
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [RFC PATCH v5 058/104] KVM: x86/mmu: Focibly use TDP MMU for TDX

From: Isaku Yamahata <isaku.yamahata@...el.com>

At this point, TDX supports TDP MMU and doesn't support legacy MMU.
Forcibly use TDP MMU for TDX irrelevant of kernel parameter to disable
TDP MMU.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index b33ace3d4456..9df6aa4da202 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -16,7 +16,12 @@ module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644);
 /* Initializes the TDP MMU for the VM, if enabled. */
 bool kvm_mmu_init_tdp_mmu(struct kvm *kvm)
 {
-	if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled))
+	/*
+	 *  Because TDX supports only TDP MMU, forcibly use TDP MMU in the case
+	 *  of TDX.
+	 */
+	if (kvm->arch.vm_type != KVM_X86_TDX_VM &&
+		(!tdp_enabled || !READ_ONCE(tdp_mmu_enabled)))
 		return false;
 
 	/* This should not be changed for the lifetime of the VM. */
-- 
2.25.1