linux-kernel - [RFC PATCH v2 07/18] KVM: TDX: Fold tdx_sept_drop_private_spte() into tdx_sept_remove_private

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Message-ID: <20250829000618.351013-8-seanjc@google.com>
Date: Thu, 28 Aug 2025 17:06:07 -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, 
	Ira Weiny <ira.weiny@...el.com>, Kai Huang <kai.huang@...el.com>, 
	Michael Roth <michael.roth@....com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, 
	Ackerley Tng <ackerleytng@...gle.com>
Subject: [RFC PATCH v2 07/18] KVM: TDX: Fold tdx_sept_drop_private_spte() into tdx_sept_remove_private_spte()

Fold tdx_sept_drop_private_spte() into tdx_sept_remove_private_spte() to
avoid having to differnatiate between "zap", "drop", and "remove", and to
eliminate dead code due to redundant checks, e.g. on an HKID being
assigned.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/tdx.c | 90 +++++++++++++++++++-----------------------
 1 file changed, 40 insertions(+), 50 deletions(-)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 50a9d81dad53..8cb6a2627eb2 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1651,55 +1651,6 @@ static int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
 	return tdx_mem_page_record_premap_cnt(kvm, gfn, level, pfn);
 }
 
-static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn,
-				      enum pg_level level, struct page *page)
-{
-	int tdx_level = pg_level_to_tdx_sept_level(level);
-	struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
-	gpa_t gpa = gfn_to_gpa(gfn);
-	u64 err, entry, level_state;
-
-	/* TODO: handle large pages. */
-	if (KVM_BUG_ON(level != PG_LEVEL_4K, kvm))
-		return -EIO;
-
-	if (KVM_BUG_ON(!is_hkid_assigned(kvm_tdx), kvm))
-		return -EIO;
-
-	/*
-	 * When zapping private page, write lock is held. So no race condition
-	 * with other vcpu sept operation.
-	 * Race with TDH.VP.ENTER due to (0-step mitigation) and Guest TDCALLs.
-	 */
-	err = tdh_mem_page_remove(&kvm_tdx->td, gpa, tdx_level, &entry,
-				  &level_state);
-
-	if (unlikely(tdx_operand_busy(err))) {
-		/*
-		 * The second retry is expected to succeed after kicking off all
-		 * other vCPUs and prevent them from invoking TDH.VP.ENTER.
-		 */
-		tdx_no_vcpus_enter_start(kvm);
-		err = tdh_mem_page_remove(&kvm_tdx->td, gpa, tdx_level, &entry,
-					  &level_state);
-		tdx_no_vcpus_enter_stop(kvm);
-	}
-
-	if (KVM_BUG_ON(err, kvm)) {
-		pr_tdx_error_2(TDH_MEM_PAGE_REMOVE, err, entry, level_state);
-		return -EIO;
-	}
-
-	err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, page);
-
-	if (KVM_BUG_ON(err, kvm)) {
-		pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);
-		return -EIO;
-	}
-	tdx_clear_page(page);
-	return 0;
-}
-
 static int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
 				     enum pg_level level, void *private_spt)
 {
@@ -1861,7 +1812,11 @@ static int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
 static int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
 					enum pg_level level, kvm_pfn_t pfn)
 {
+	int tdx_level = pg_level_to_tdx_sept_level(level);
+	struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
 	struct page *page = pfn_to_page(pfn);
+	gpa_t gpa = gfn_to_gpa(gfn);
+	u64 err, entry, level_state;
 	int ret;
 
 	/*
@@ -1872,6 +1827,10 @@ static int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
 	if (KVM_BUG_ON(!is_hkid_assigned(to_kvm_tdx(kvm)), kvm))
 		return -EIO;
 
+	/* TODO: handle large pages. */
+	if (KVM_BUG_ON(level != PG_LEVEL_4K, kvm))
+		return -EIO;
+
 	ret = tdx_sept_zap_private_spte(kvm, gfn, level, page);
 	if (ret <= 0)
 		return ret;
@@ -1882,7 +1841,38 @@ static int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
 	 */
 	tdx_track(kvm);
 
-	return tdx_sept_drop_private_spte(kvm, gfn, level, page);
+	/*
+	 * When zapping private page, write lock is held. So no race condition
+	 * with other vcpu sept operation.
+	 * Race with TDH.VP.ENTER due to (0-step mitigation) and Guest TDCALLs.
+	 */
+	err = tdh_mem_page_remove(&kvm_tdx->td, gpa, tdx_level, &entry,
+				  &level_state);
+
+	if (unlikely(tdx_operand_busy(err))) {
+		/*
+		 * The second retry is expected to succeed after kicking off all
+		 * other vCPUs and prevent them from invoking TDH.VP.ENTER.
+		 */
+		tdx_no_vcpus_enter_start(kvm);
+		err = tdh_mem_page_remove(&kvm_tdx->td, gpa, tdx_level, &entry,
+					  &level_state);
+		tdx_no_vcpus_enter_stop(kvm);
+	}
+
+	if (KVM_BUG_ON(err, kvm)) {
+		pr_tdx_error_2(TDH_MEM_PAGE_REMOVE, err, entry, level_state);
+		return -EIO;
+	}
+
+	err = tdh_phymem_page_wbinvd_hkid((u16)kvm_tdx->hkid, page);
+	if (KVM_BUG_ON(err, kvm)) {
+		pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);
+		return -EIO;
+	}
+
+	tdx_clear_page(page);
+	return 0;
 }
 
 void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
-- 
2.51.0.318.gd7df087d1a-goog