Commit 10605204 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Revert "KVM: x86/mmu: Remove is_obsolete() call" 



Now that the fast invalidate mechanism has been reintroduced, restore
the performance tweaks for fast invalidation that existed prior to its
removal.

Paraphrasing the original changelog (commit 5ff05683 was itself a
partial revert):

  Don't force reloading the remote mmu when zapping an obsolete page, as
  a MMU_RELOAD request has already been issued by kvm_mmu_zap_all_fast()
  immediately after incrementing mmu_valid_gen, i.e. after marking pages
  obsolete.

This reverts commit 5ff05683.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 31741eb1

arch/x86/kvm/mmu.c

+23 −6
Original line number Diff line number Diff line
@@ -2752,7 +2752,12 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, 
	} else {

		list_move(&sp->link, &kvm->arch.active_mmu_pages);



		if (!sp->role.invalid)

		/*

		 * Obsolete pages cannot be used on any vCPUs, see the comment

		 * in kvm_mmu_zap_all_fast().  Note, is_obsolete_sp() also

		 * treats invalid shadow pages as being obsolete.

		 */

		if (!is_obsolete_sp(kvm, sp))

			kvm_reload_remote_mmus(kvm);

	}
@@ -5675,7 +5680,6 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) 
static void kvm_zap_obsolete_pages(struct kvm *kvm)

{

	struct kvm_mmu_page *sp, *node;

	LIST_HEAD(invalid_list);

	int nr_zapped, batch = 0;



restart:
@@ -5708,8 +5712,8 @@ restart: 
			goto restart;

		}



		if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list,

					       &nr_zapped)) {

		if (__kvm_mmu_prepare_zap_page(kvm, sp,

				&kvm->arch.zapped_obsolete_pages, &nr_zapped)) {

			batch += nr_zapped;

			goto restart;

		}
@@ -5720,7 +5724,7 @@ restart: 
	 * KVM is not in the middle of a lockless shadow page table walk, which

	 * may reference the pages.

	 */

	kvm_mmu_commit_zap_page(kvm, &invalid_list);

	kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);

}



/*
@@ -5752,6 +5756,11 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) 
	spin_unlock(&kvm->mmu_lock);

}



static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)

{

	return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));

}



static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,

			struct kvm_memory_slot *slot,

			struct kvm_page_track_notifier_node *node)
@@ -6022,16 +6031,24 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 
		 * want to shrink a VM that only started to populate its MMU

		 * anyway.

		 */

		if (!kvm->arch.n_used_mmu_pages)

		if (!kvm->arch.n_used_mmu_pages &&

		    !kvm_has_zapped_obsolete_pages(kvm))

			continue;



		idx = srcu_read_lock(&kvm->srcu);

		spin_lock(&kvm->mmu_lock);



		if (kvm_has_zapped_obsolete_pages(kvm)) {

			kvm_mmu_commit_zap_page(kvm,

			      &kvm->arch.zapped_obsolete_pages);

			goto unlock;

		}



		if (prepare_zap_oldest_mmu_page(kvm, &invalid_list))

			freed++;

		kvm_mmu_commit_zap_page(kvm, &invalid_list);



unlock:

		spin_unlock(&kvm->mmu_lock);

		srcu_read_unlock(&kvm->srcu, idx);

arch/x86/kvm/x86.c

+1 −0
Original line number Diff line number Diff line
@@ -9425,6 +9425,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 


	INIT_HLIST_HEAD(&kvm->arch.mask_notifier_list);

	INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);

	INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);

	INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);

	atomic_set(&kvm->arch.noncoherent_dma_count, 0);

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