linux-kernel - [RFC PATCH 03/12] Revert "KVM: x86/tdp_mmu: Add a helper function to walk down the TDP MMU"

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Message-ID: <20250827000522.4022426-4-seanjc@google.com>
Date: Tue, 26 Aug 2025 17:05:13 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Michael Roth <michael.roth@....com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Ira Weiny <ira.weiny@...el.com>, Vishal Annapurve <vannapurve@...gle.com>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: [RFC PATCH 03/12] Revert "KVM: x86/tdp_mmu: Add a helper function to
 walk down the TDP MMU"

Remove the helper and exports that were added to allow TDX code to reuse
kvm_tdp_map_page() for its gmem post-populated flow now that a dedicated
TDP MMU API is provided to install a mapping given a gfn+pfn pair.

This reverts commit 2608f105760115e94a03efd9f12f8fbfd1f9af4b.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu.h         |  2 --
 arch/x86/kvm/mmu/mmu.c     |  4 ++--
 arch/x86/kvm/mmu/tdp_mmu.c | 37 +++++--------------------------------
 3 files changed, 7 insertions(+), 36 deletions(-)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 697b90a97f43..dc6b965cea4f 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -257,8 +257,6 @@ extern bool tdp_mmu_enabled;
 #define tdp_mmu_enabled false
 #endif
 
-bool kvm_tdp_mmu_gpa_is_mapped(struct kvm_vcpu *vcpu, u64 gpa);
-int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code, u8 *level);
 int kvm_tdp_mmu_map_private_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn);
 
 static inline bool kvm_memslots_have_rmaps(struct kvm *kvm)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d3625e00baf9..f532beed9029 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4900,7 +4900,8 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	return direct_page_fault(vcpu, fault);
 }
 
-int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code, u8 *level)
+static int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code,
+			    u8 *level)
 {
 	int r;
 
@@ -4942,7 +4943,6 @@ int kvm_tdp_map_page(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code, u8 *level
 		return -EIO;
 	}
 }
-EXPORT_SYMBOL_GPL(kvm_tdp_map_page);
 
 long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,
 				    struct kvm_pre_fault_memory *range)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 7f3d7229b2c1..1b559a50db51 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1910,13 +1910,16 @@ bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm,
  *
  * Must be called between kvm_tdp_mmu_walk_lockless_{begin,end}.
  */
-static int __kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,
-				  struct kvm_mmu_page *root)
+int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,
+			 int *root_level)
 {
+	struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa);
 	struct tdp_iter iter;
 	gfn_t gfn = addr >> PAGE_SHIFT;
 	int leaf = -1;
 
+	*root_level = vcpu->arch.mmu->root_role.level;
+
 	for_each_tdp_pte(iter, vcpu->kvm, root, gfn, gfn + 1) {
 		leaf = iter.level;
 		sptes[leaf] = iter.old_spte;
@@ -1925,36 +1928,6 @@ static int __kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,
 	return leaf;
 }
 
-int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes,
-			 int *root_level)
-{
-	struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa);
-	*root_level = vcpu->arch.mmu->root_role.level;
-
-	return __kvm_tdp_mmu_get_walk(vcpu, addr, sptes, root);
-}
-
-bool kvm_tdp_mmu_gpa_is_mapped(struct kvm_vcpu *vcpu, u64 gpa)
-{
-	struct kvm *kvm = vcpu->kvm;
-	bool is_direct = kvm_is_addr_direct(kvm, gpa);
-	hpa_t root = is_direct ? vcpu->arch.mmu->root.hpa :
-				 vcpu->arch.mmu->mirror_root_hpa;
-	u64 sptes[PT64_ROOT_MAX_LEVEL + 1], spte;
-	int leaf;
-
-	lockdep_assert_held(&kvm->mmu_lock);
-	rcu_read_lock();
-	leaf = __kvm_tdp_mmu_get_walk(vcpu, gpa, sptes, root_to_sp(root));
-	rcu_read_unlock();
-	if (leaf < 0)
-		return false;
-
-	spte = sptes[leaf];
-	return is_shadow_present_pte(spte) && is_last_spte(spte, leaf);
-}
-EXPORT_SYMBOL_GPL(kvm_tdp_mmu_gpa_is_mapped);
-
 /*
  * Returns the last level spte pointer of the shadow page walk for the given
  * gpa, and sets *spte to the spte value. This spte may be non-preset. If no
-- 
2.51.0.268.g9569e192d0-goog