[PATCH v6 05/18] KVM: x86/mmu: Add an is_mirror member for union kvm_mmu_page_role

[Paolo Bonzini]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

Introduce a "is_mirror" member to the kvm_mmu_page_role union to identify
SPTEs associated with the mirrored EPT.

The TDX module maintains the private half of the EPT mapped in the TD in
its protected memory. KVM keeps a copy of the private GPAs in a mirrored
EPT tree within host memory. This "is_mirror" attribute enables vCPUs to
find and get the root page of mirrored EPT from the MMU root list for a
guest TD. This also allows KVM MMU code to detect changes in mirrored EPT
according to the "is_mirror" mmu page role and propagate the changes to
the private EPT managed by TDX module.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Message-ID: <20240718211230.1492011-6-rick.p.edgecombe@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/include/asm/kvm_host.h | 3 ++-
 arch/x86/kvm/mmu/mmu_internal.h | 5 +++++
 arch/x86/kvm/mmu/spte.h         | 5 +++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5f020b097922..cae88f023caf 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -349,7 +349,8 @@ union kvm_mmu_page_role {
 		unsigned ad_disabled:1;
 		unsigned guest_mode:1;
 		unsigned passthrough:1;
-		unsigned :5;
+		unsigned is_mirror:1;
+		unsigned :4;
 
 		/*
 		 * This is left at the top of the word so that
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index d9425064ecc5..ff00341f26a2 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -157,6 +157,11 @@ static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
 	return kvm_mmu_role_as_id(sp->role);
 }
 
+static inline bool is_mirror_sp(const struct kvm_mmu_page *sp)
+{
+	return sp->role.is_mirror;
+}
+
 static inline void kvm_mmu_alloc_external_spt(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 {
 	/*
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index af10bc0380a3..59746854c0af 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -276,6 +276,11 @@ static inline struct kvm_mmu_page *root_to_sp(hpa_t root)
 	return spte_to_child_sp(root);
 }
 
+static inline bool is_mirror_sptep(tdp_ptep_t sptep)
+{
+	return is_mirror_sp(sptep_to_sp(rcu_dereference(sptep)));
+}
+
 static inline bool is_mmio_spte(struct kvm *kvm, u64 spte)
 {
 	return (spte & shadow_mmio_mask) == kvm->arch.shadow_mmio_value &&
-- 
2.43.5