linux-kernel - [RFC PATCH v5 07/45] KVM: x86/mmu: Plumb the SPTE _pointer_ into the TDP MMU's handle_changed

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Message-ID: <20260129011517.3545883-8-seanjc@google.com>
Date: Wed, 28 Jan 2026 17:14:39 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	Kiryl Shutsemau <kas@...nel.org>, Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	kvm@...r.kernel.org, Kai Huang <kai.huang@...el.com>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Ackerley Tng <ackerleytng@...gle.com>, 
	Sagi Shahar <sagis@...gle.com>, Binbin Wu <binbin.wu@...ux.intel.com>, 
	Xiaoyao Li <xiaoyao.li@...el.com>, Isaku Yamahata <isaku.yamahata@...el.com>
Subject: [RFC PATCH v5 07/45] KVM: x86/mmu: Plumb the SPTE _pointer_ into the
 TDP MMU's handle_changed_spte()

Plumb the SPTE pointer into handle_changed_spte() so that remove leaf
mirror entries can be forwarded to TDX in handle_changed_spte(), instead
of effectively requiring callers to manually do so.  Relying on each
caller to invoke .remove_external_spte() is confusing and brittle, e.g.
subtly relies tdp_mmu_set_spte_atomic() never removing SPTEs.  This will
also allow consolidating all S-EPT updates into a single kvm_x86_ops hook.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 6fb48b217f5b..8743cd020d12 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -320,9 +320,9 @@ void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu, bool mirror)
 	}
 }
 
-static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
-				u64 old_spte, u64 new_spte, int level,
-				bool shared);
+static void handle_changed_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
+				gfn_t gfn, u64 old_spte, u64 new_spte,
+				int level, bool shared);
 
 static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
@@ -471,7 +471,7 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
 			old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte,
 							  FROZEN_SPTE, level);
 		}
-		handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn,
+		handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), sptep, gfn,
 				    old_spte, FROZEN_SPTE, level, shared);
 
 		if (is_mirror_sp(sp)) {
@@ -499,6 +499,7 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
  * handle_changed_spte - handle bookkeeping associated with an SPTE change
  * @kvm: kvm instance
  * @as_id: the address space of the paging structure the SPTE was a part of
+ * @sptep: pointer to the SPTE
  * @gfn: the base GFN that was mapped by the SPTE
  * @old_spte: The value of the SPTE before the change
  * @new_spte: The value of the SPTE after the change
@@ -511,9 +512,9 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)
  * dirty logging updates are handled in common code, not here (see make_spte()
  * and fast_pf_fix_direct_spte()).
  */
-static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
-				u64 old_spte, u64 new_spte, int level,
-				bool shared)
+static void handle_changed_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
+				gfn_t gfn, u64 old_spte, u64 new_spte,
+				int level, bool shared)
 {
 	bool was_present = is_shadow_present_pte(old_spte);
 	bool is_present = is_shadow_present_pte(new_spte);
@@ -685,8 +686,8 @@ static inline int __must_check tdp_mmu_set_spte_atomic(struct kvm *kvm,
 	if (ret)
 		return ret;
 
-	handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
-			    new_spte, iter->level, true);
+	handle_changed_spte(kvm, iter->as_id, iter->sptep, iter->gfn,
+			    iter->old_spte, new_spte, iter->level, true);
 
 	return 0;
 }
@@ -720,7 +721,7 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep,
 
 	old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte, new_spte, level);
 
-	handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false);
+	handle_changed_spte(kvm, as_id, sptep, gfn, old_spte, new_spte, level, false);
 
 	/*
 	 * Users that do non-atomic setting of PTEs don't operate on mirror
-- 
2.53.0.rc1.217.geba53bf80e-goog