linux-kernel - Re: [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: <12601cb031b7a19dfc00463e6d6948dfa6187172.camel@intel.com>
Date: Thu, 30 Oct 2025 22:17:18 +0000
From: "Huang, Kai" <kai.huang@...el.com>
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Subject: Re: [PATCH v4 05/28] KVM: x86/mmu: WARN if KVM attempts to map into
 an invalid TDP MMU root

On Thu, 2025-10-30 at 13:09 -0700, Sean Christopherson wrote:
> 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>

Reviewed-by: Kai Huang <kai.huang@...el.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