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    Subject[PATCH 5.10 095/126] KVM: x86/mmu: Factor out functions to add/remove TDP MMU pages
    Date
    From: Ben Gardon <bgardon@google.com>

    [ Upstream commit a9442f594147f95307f691cfba0c31e25dc79b9d ]

    Move the work of adding and removing TDP MMU pages to/from "secondary"
    data structures to helper functions. These functions will be built on in
    future commits to enable MMU operations to proceed (mostly) in parallel.

    No functional change expected.

    Signed-off-by: Ben Gardon <bgardon@google.com>
    Message-Id: <20210202185734.1680553-20-bgardon@google.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kvm/mmu/tdp_mmu.c | 47 +++++++++++++++++++++++++++++++-------
    1 file changed, 39 insertions(+), 8 deletions(-)

    diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
    index 136311be5890..14d69c01c710 100644
    --- a/arch/x86/kvm/mmu/tdp_mmu.c
    +++ b/arch/x86/kvm/mmu/tdp_mmu.c
    @@ -262,6 +262,39 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
    }
    }

    +/**
    + * tdp_mmu_link_page - Add a new page to the list of pages used by the TDP MMU
    + *
    + * @kvm: kvm instance
    + * @sp: the new page
    + * @account_nx: This page replaces a NX large page and should be marked for
    + * eventual reclaim.
    + */
    +static void tdp_mmu_link_page(struct kvm *kvm, struct kvm_mmu_page *sp,
    + bool account_nx)
    +{
    + lockdep_assert_held_write(&kvm->mmu_lock);
    +
    + list_add(&sp->link, &kvm->arch.tdp_mmu_pages);
    + if (account_nx)
    + account_huge_nx_page(kvm, sp);
    +}
    +
    +/**
    + * tdp_mmu_unlink_page - Remove page from the list of pages used by the TDP MMU
    + *
    + * @kvm: kvm instance
    + * @sp: the page to be removed
    + */
    +static void tdp_mmu_unlink_page(struct kvm *kvm, struct kvm_mmu_page *sp)
    +{
    + lockdep_assert_held_write(&kvm->mmu_lock);
    +
    + list_del(&sp->link);
    + if (sp->lpage_disallowed)
    + unaccount_huge_nx_page(kvm, sp);
    +}
    +
    /**
    * handle_removed_tdp_mmu_page - handle a pt removed from the TDP structure
    *
    @@ -281,10 +314,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, u64 *pt)

    trace_kvm_mmu_prepare_zap_page(sp);

    - list_del(&sp->link);
    -
    - if (sp->lpage_disallowed)
    - unaccount_huge_nx_page(kvm, sp);
    + tdp_mmu_unlink_page(kvm, sp);

    for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
    old_child_spte = READ_ONCE(*(pt + i));
    @@ -704,15 +734,16 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,

    if (!is_shadow_present_pte(iter.old_spte)) {
    sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level);
    - list_add(&sp->link, &vcpu->kvm->arch.tdp_mmu_pages);
    child_pt = sp->spt;
    +
    + tdp_mmu_link_page(vcpu->kvm, sp,
    + huge_page_disallowed &&
    + req_level >= iter.level);
    +
    new_spte = make_nonleaf_spte(child_pt,
    !shadow_accessed_mask);

    trace_kvm_mmu_get_page(sp, true);
    - if (huge_page_disallowed && req_level >= iter.level)
    - account_huge_nx_page(vcpu->kvm, sp);
    -
    tdp_mmu_set_spte(vcpu->kvm, &iter, new_spte);
    }
    }
    --
    2.30.1


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