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SubjectRe: [PATCH 09/10 RFC] KVM: x86: MMU: Move parent_pte handling from kvm_mmu_get_page() to link_shadow_page()
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On 11/12/2015 07:56 PM, Takuya Yoshikawa wrote:
> Every time kvm_mmu_get_page() is called with a non-NULL parent_pte
> argument, link_shadow_page() follows that to set the parent entry so
> that the new mapping will point to the returned page table.
>
> Moving parent_pte handling there allows to clean up the code because
> parent_pte is passed to kvm_mmu_get_page() just for mark_unsync() and
> mmu_page_add_parent_pte().
>
> Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
> ---
> arch/x86/kvm/mmu.c | 21 ++++++++-------------
> arch/x86/kvm/paging_tmpl.h | 6 ++----
> 2 files changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 9273cd4..33fe720 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2108,14 +2108,9 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
> if (sp->unsync_children) {
> kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
> kvm_mmu_mark_parents_unsync(sp);
> - 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);
> @@ -2127,7 +2122,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
> sp = kvm_mmu_alloc_page(vcpu, direct);
>
> sp->parent_ptes.val = 0;
> - mmu_page_add_parent_pte(vcpu, sp, parent_pte);
>
> sp->gfn = gfn;
> sp->role = role;
> @@ -2196,7 +2190,8 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
> return __shadow_walk_next(iterator, *iterator->sptep);
> }
>
> -static void link_shadow_page(u64 *sptep, struct kvm_mmu_page *sp, bool accessed)
> +static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
> + struct kvm_mmu_page *sp, bool accessed)
> {
> u64 spte;
>
> @@ -2210,6 +2205,11 @@ static void link_shadow_page(u64 *sptep, struct kvm_mmu_page *sp, bool accessed)
> spte |= shadow_accessed_mask;
>
> mmu_spte_set(sptep, spte);
> +
> + if (sp->unsync_children || sp->unsync)
> + mark_unsync(sptep);

Why are these needed?



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