linux-kernel - Re: [PATCH v2 03/18] KVM: x86/mmu: WARN if PAE roots linger after kvm_mmu

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Message-ID: <Yg/UCQggoKQ27pVm@google.com>
Date:   Fri, 18 Feb 2022 17:14:49 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v2 03/18] KVM: x86/mmu: WARN if PAE roots linger after
 kvm_mmu_unload

On Thu, Feb 17, 2022, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/mmu/mmu.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 296f8723f9ae..a67071ac80f3 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5086,12 +5086,21 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu)
>  	return r;
>  }
>  
> +static void __kvm_mmu_unload(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
> +{
> +	int i;
> +	kvm_mmu_free_roots(vcpu, mmu, KVM_MMU_ROOTS_ALL);
> +	WARN_ON(VALID_PAGE(mmu->root_hpa));
> +	if (mmu->pae_root) {
> +		for (i = 0; i < 4; ++i)
> +			WARN_ON(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
> +	}
> +}
> +
>  void kvm_mmu_unload(struct kvm_vcpu *vcpu)
>  {
> -	kvm_mmu_free_roots(vcpu, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL);
> -	WARN_ON(VALID_PAGE(vcpu->arch.root_mmu.root_hpa));
> -	kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL);
> -	WARN_ON(VALID_PAGE(vcpu->arch.guest_mmu.root_hpa));
> +	__kvm_mmu_unload(vcpu, &vcpu->arch.root_mmu);
> +	__kvm_mmu_unload(vcpu, &vcpu->arch.guest_mmu);

Can we just drop this one?  Checkpatch doesn't like it, and IMO the existing asserts
are unnecessary.  IIRC you said this one never actually fired?

WARNING: Missing commit description - Add an appropriate one

WARNING: Missing a blank line after declarations
#22: FILE: arch/x86/kvm/mmu/mmu.c:5092:
+	int i;
+	kvm_mmu_free_roots(vcpu, mmu, KVM_MMU_ROOTS_ALL);


>  }
>  
>  static bool need_remote_flush(u64 old, u64 new)
> -- 
> 2.31.1
> 
>