linux-kernel - [PATCH v4 05/28] KVM: x86/mmu: WARN if KVM attempts to map into an invalid TDP MMU root

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Message-ID: <20251030200951.3402865-6-seanjc@google.com>
Date: Thu, 30 Oct 2025 13:09:28 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, Sean Christopherson <seanjc@...gle.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, "Kirill A. Shutemov" <kas@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, x86@...nel.org, linux-coco@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, Ira Weiny <ira.weiny@...el.com>, 
	Kai Huang <kai.huang@...el.com>, Binbin Wu <binbin.wu@...ux.intel.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: [PATCH v4 05/28] KVM: x86/mmu: WARN if KVM attempts to map into an
 invalid TDP MMU root

When mapping into the TDP MMU, WARN (if KVM_PROVE_MMU=y) if the root is
invalid, e.g. if KVM is attempting to insert a mapping without checking if
the information and MMU context is fresh.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index c5734ca5c17d..440fd8f80397 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1273,6 +1273,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	struct kvm_mmu_page *sp;
 	int ret = RET_PF_RETRY;
 
+	KVM_MMU_WARN_ON(!root || root->role.invalid);
+
 	kvm_mmu_hugepage_adjust(vcpu, fault);
 
 	trace_kvm_mmu_spte_requested(fault);
-- 
2.51.1.930.gacf6e81ea2-goog