[PATCH 7/9] KVM: MMU: introduce kvm_zap_gfn_range()

[guangrong.xiao@linux.intel.com]

From: Xiao Guangrong <guangrong.xiao@linux.intel.com>

It is used to zap all the rmaps of the specified gfn range and will
be used by the later patch

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 arch/x86/kvm/mmu.c | 30 ++++++++++++++++++++++++++++++
 arch/x86/kvm/mmu.h |  1 +
 2 files changed, 31 insertions(+)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5d90a22..aa9aad0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4520,6 +4520,36 @@ slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot,
 				 PT_PAGE_TABLE_LEVEL, lock_flush_tlb);
 }
 
+void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	bool flush = false;
+
+	slots = kvm_memslots(kvm);
+
+	spin_lock(&kvm->mmu_lock);
+	kvm_for_each_memslot(memslot, slots) {
+		gfn_t start, end;
+
+		start = max(gfn_start, memslot->base_gfn);
+		end = min(gfn_end, memslot->base_gfn + memslot->npages);
+		if (start >= end)
+			continue;
+
+		flush |= slot_handle_level_range(kvm, memslot, kvm_zap_rmapp,
+			      PT_PAGE_TABLE_LEVEL,
+			      PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES - 1,
+			      start, end - 1, true);
+	}
+
+	if (flush)
+		kvm_flush_remote_tlbs(kvm);
+	spin_unlock(&kvm->mmu_lock);
+
+}
+EXPORT_SYMBOL_GPL(kvm_zap_gfn_range);
+
 static bool slot_rmap_write_protect(struct kvm *kvm, unsigned long *rmapp)
 {
 	return __rmap_write_protect(kvm, rmapp, false);
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index c7d6563..44b75f3 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -170,4 +170,5 @@ static inline bool permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 }
 
 void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm);
+void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
 #endif
-- 
1.9.3