Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot"

This reverts commit 4e103134.
Alex Williamson reported regressions with device assignment with
this patch.  Even though the bug is probably elsewhere and still
latent, this is needed to fix the regression.

Fixes: 4e103134 ("KVM: x86/mmu: Zap only the relevant pages when removing a memslot", 2019-02-05)
Reported-by: NAlex Willamson <alex.williamson@redhat.com>
Cc: stable@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -5653,38 +5653,7 @@ static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
 			struct kvm_memory_slot *slot,
 			struct kvm_page_track_notifier_node *node)
 {
-	struct kvm_mmu_page *sp;
-	LIST_HEAD(invalid_list);
-	unsigned long i;
-	bool flush;
-	gfn_t gfn;
-
-	spin_lock(&kvm->mmu_lock);
-
-	if (list_empty(&kvm->arch.active_mmu_pages))
-		goto out_unlock;
-
-	flush = slot_handle_all_level(kvm, slot, kvm_zap_rmapp, false);
-
-	for (i = 0; i < slot->npages; i++) {
-		gfn = slot->base_gfn + i;
-
-		for_each_valid_sp(kvm, sp, gfn) {
-			if (sp->gfn != gfn)
-				continue;
-
-			kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
-		}
-		if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
-			kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush);
-			flush = false;
-			cond_resched_lock(&kvm->mmu_lock);
-		}
-	}
-	kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush);
-
-out_unlock:
-	spin_unlock(&kvm->mmu_lock);
+	kvm_mmu_zap_all(kvm);
 }
 
 void kvm_mmu_init_vm(struct kvm *kvm)