linux-kernel - Re: [RFC PATCH V3 2/4] KVM: X86: Introduce role.glevel for level expanded pagetable

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Message-ID: <CAJhGHyBajHJ8hDy--7mofH=25Ji6L2+jUvfZ1oTQ2gcqqupyFA@mail.gmail.com>
Date:   Thu, 31 Mar 2022 00:01:12 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Lai Jiangshan <jiangshan.ljs@...group.com>,
        Jonathan Corbet <corbet@....net>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        linux-doc@...r.kernel.org
Subject: Re: [RFC PATCH V3 2/4] KVM: X86: Introduce role.glevel for level
 expanded pagetable

On Wed, Mar 30, 2022 at 9:21 PM Lai Jiangshan <jiangshanlai@...il.com> wrote:

> @@ -1713,7 +1721,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, gfn_t gfn,
>
>         sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
>         sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
> -       if (!role.direct)
> +       if (role.glevel == role.level)
>                 sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
>         set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
>
> @@ -2054,6 +2062,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
>                 quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
>                 role.quadrant = quadrant;
>         }
> +       if (level < role.glevel)
> +               role.glevel = level;

missing:

if (direct)
   role.glevel = 0;

>
>         sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
>         for_each_valid_sp(vcpu->kvm, sp, sp_list) {