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    Subject[PATCH 08/10] KVM: x86: MMU: Use for_each_rmap_spte macro instead of pte_list_walk()
    kvm_mmu_mark_parents_unsync() alone uses pte_list_walk(), witch does
    nearly the same as the for_each_rmap_spte macro. The only difference
    is that is_shadow_present_pte() checks cannot be placed there because
    kvm_mmu_mark_parents_unsync() can be called with a new parent pointer
    whose entry is not set yet.

    By calling mark_unsync() separately for the parent and adding the parent
    pointer to the parent_ptes chain later in kvm_mmu_get_page(), the macro
    works with no problem.

    Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
    ---
    arch/x86/kvm/mmu.c | 36 +++++++++++++-----------------------
    1 file changed, 13 insertions(+), 23 deletions(-)

    diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    index 7f46e3e..4e29d9a 100644
    --- a/arch/x86/kvm/mmu.c
    +++ b/arch/x86/kvm/mmu.c
    @@ -1007,26 +1007,6 @@ static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head)
    }
    }

    -typedef void (*pte_list_walk_fn) (u64 *spte);
    -static void pte_list_walk(struct kvm_rmap_head *rmap_head, pte_list_walk_fn fn)
    -{
    - struct pte_list_desc *desc;
    - int i;
    -
    - if (!rmap_head->val)
    - return;
    -
    - if (!(rmap_head->val & 1))
    - return fn((u64 *)rmap_head->val);
    -
    - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
    - while (desc) {
    - for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
    - fn(desc->sptes[i]);
    - desc = desc->more;
    - }
    -}
    -
    static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level,
    struct kvm_memory_slot *slot)
    {
    @@ -1749,7 +1729,12 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct
    static void mark_unsync(u64 *spte);
    static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
    {
    - pte_list_walk(&sp->parent_ptes, mark_unsync);
    + u64 *sptep;
    + struct rmap_iterator iter;
    +
    + for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) {
    + mark_unsync(sptep);
    + }
    }

    static void mark_unsync(u64 *spte)
    @@ -2119,12 +2104,17 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
    if (sp->unsync && kvm_sync_page_transient(vcpu, sp))
    break;

    - mmu_page_add_parent_pte(vcpu, sp, parent_pte);
    if (sp->unsync_children) {
    kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
    kvm_mmu_mark_parents_unsync(sp);
    - } else if (sp->unsync)
    + if (parent_pte)
    + mark_unsync(parent_pte);
    + } else if (sp->unsync) {
    kvm_mmu_mark_parents_unsync(sp);
    + if (parent_pte)
    + mark_unsync(parent_pte);
    + }
    + mmu_page_add_parent_pte(vcpu, sp, parent_pte);

    __clear_sp_write_flooding_count(sp);
    trace_kvm_mmu_get_page(sp, false);
    --
    2.1.0


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