From: Sean Christopherson <seanjc@google.com>
To: Wei Huang <wei.huang2@amd.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, vkuznets@redhat.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 v2 2/3] KVM: x86: Handle the case of 5-level shadow page table
Date: Mon, 9 Aug 2021 15:17:12 +0000 [thread overview]
Message-ID: <YRFG+NDkjVK0myDn@google.com> (raw)
In-Reply-To: <20210808192658.2923641-3-wei.huang2@amd.com>
On Sun, Aug 08, 2021, Wei Huang wrote:
> @@ -3457,10 +3457,19 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
> mmu->pae_root[i] = root | pm_mask;
> }
>
> - if (mmu->shadow_root_level == PT64_ROOT_4LEVEL)
> + /*
> + * Depending on the shadow_root_level, build the root_hpa table by
> + * chaining either pml5->pml4->pae or pml4->pae.
> + */
> + mmu->root_hpa = __pa(mmu->pae_root);
> + if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL) {
> + mmu->pml4_root[0] = mmu->root_hpa | pm_mask;
> mmu->root_hpa = __pa(mmu->pml4_root);
> - else
> - mmu->root_hpa = __pa(mmu->pae_root);
> + }
> + if (mmu->shadow_root_level == PT64_ROOT_5LEVEL) {
> + mmu->pml5_root[0] = mmu->root_hpa | pm_mask;
> + mmu->root_hpa = __pa(mmu->pml5_root);
> + }
I still really dislike this approach, it requires visually connecting multiple
statements to understand the chain. I don't see any advantage (the 6-level paging
comment was 99.9% a joke) of rewriting root_hpa other than that's how it's done today.
In the future, please give reviewers ample opportunity to respond before sending
a new version if there's disagreement, otherwise the conversation gets carried
over into a different thread and loses the original context.
>
> set_root_pgd:
> mmu->root_pgd = root_pgd;
next prev parent reply other threads:[~2021-08-09 15:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-08 19:26 [PATCH v2 0/3] SVM 5-level page table support Wei Huang
2021-08-08 19:26 ` [PATCH v2 1/3] KVM: x86: Allow CPU to force vendor-specific TDP level Wei Huang
2021-08-09 3:58 ` Yu Zhang
2021-08-09 4:11 ` Wei Huang
2021-08-09 4:27 ` Yu Zhang
2021-08-09 4:33 ` Wei Huang
2021-08-09 6:42 ` Yu Zhang
2021-08-09 15:30 ` Sean Christopherson
2021-08-09 21:49 ` Jim Mattson
2021-08-10 9:23 ` Paolo Bonzini
2021-08-10 7:40 ` Yu Zhang
2021-08-10 9:25 ` Paolo Bonzini
2021-08-10 11:00 ` Yu Zhang
2021-08-10 12:47 ` Paolo Bonzini
2021-08-10 14:37 ` Yu Zhang
2021-08-08 19:26 ` [PATCH v2 2/3] KVM: x86: Handle the case of 5-level shadow page table Wei Huang
2021-08-09 15:17 ` Sean Christopherson [this message]
2021-08-09 17:03 ` Wei Huang
2021-08-08 19:26 ` [PATCH v2 3/3] KVM: SVM: Add 5-level page table support for SVM Wei Huang
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