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From: Tom Lendacky <thomas.lendacky@amd.com>
To: Wei Huang <wei.huang2@amd.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, pbonzini@redhat.com,
	vkuznets@redhat.com, seanjc@google.com, wanpengli@tencent.com,
	jmattson@google.com, joro@8bytes.org, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com
Subject: Re: [PATCH v3 2/3] KVM: x86: Handle the case of 5-level shadow page table
Date: Wed, 18 Aug 2021 13:00:14 -0500	[thread overview]
Message-ID: <49f37adb-973c-aec6-9b9e-30699113af18@amd.com> (raw)
In-Reply-To: <20210818165549.3771014-3-wei.huang2@amd.com>

On 8/18/21 11:55 AM, Wei Huang wrote:
> When the 5-level page table CPU flag is exposed, KVM code needs to handle
> this case by pointing mmu->root_hpa to a properly-constructed 5-level page
> table.
> 
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> ---

...

>  	pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT);
> -	if (!pml4_root) {
> -		free_page((unsigned long)pae_root);
> -		return -ENOMEM;
> +	if (!pml4_root)
> +		goto err_pml4;
> +
> +	if (mmu->shadow_root_level > PT64_ROOT_4LEVEL) {
> +		pml5_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT);
> +		if (!pml5_root)
> +			goto err_pml5;
>  	}
>  
>  	mmu->pae_root = pae_root;
>  	mmu->pml4_root = pml4_root;
> +	mmu->pml5_root = pml5_root;

It looks like pml5_root could be used uninitialized here. You should
initialize it to NULL or set it to NULL as an else path of the new check
above.

Thanks,
Tom

>  
>  	return 0;
> +err_pml5:
> +	free_page((unsigned long)pml4_root);
> +err_pml4:
> +	free_page((unsigned long)pae_root);
> +	return -ENOMEM;
>  }
>  
>  void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
> @@ -5364,6 +5377,7 @@ static void free_mmu_pages(struct kvm_mmu *mmu)
>  		set_memory_encrypted((unsigned long)mmu->pae_root, 1);
>  	free_page((unsigned long)mmu->pae_root);
>  	free_page((unsigned long)mmu->pml4_root);
> +	free_page((unsigned long)mmu->pml5_root);
>  }
>  
>  static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
> 

  parent reply	other threads:[~2021-08-18 18:00 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18 16:55 [PATCH v3 0/3] SVM 5-level page table support Wei Huang
2021-08-18 16:55 ` [PATCH v3 1/3] KVM: x86: Allow CPU to force vendor-specific TDP level Wei Huang
2021-08-18 16:55 ` [PATCH v3 2/3] KVM: x86: Handle the case of 5-level shadow page table Wei Huang
2021-08-18 17:15   ` Sean Christopherson
2021-08-19 16:36     ` Paolo Bonzini
2021-08-18 18:00   ` Tom Lendacky [this message]
2021-08-18 16:55 ` [PATCH v3 3/3] KVM: SVM: Add 5-level page table support for SVM Wei Huang
2021-08-18 17:32   ` Sean Christopherson
2021-08-19 16:38     ` Paolo Bonzini
2021-08-19 16:43 ` [PATCH v3 0/3] SVM 5-level page table support Paolo Bonzini
2021-08-23  9:20   ` Maxim Levitsky
2021-08-23 15:15     ` Wei Huang
2021-08-23 16:10       ` Sean Christopherson
2021-08-23 18:10         ` Maxim Levitsky
2021-08-23 18:06       ` Maxim Levitsky

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