diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index ad6f837..fd0956f 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -230,6 +230,24 @@ int kvm_remove_breakpoint(CPUState *cpu, target_ulong addr,
                           target_ulong len, int type);
 void kvm_remove_all_breakpoints(CPUState *cpu);
 int kvm_update_guest_debug(CPUState *cpu, unsigned long reinject_trap);
+
+/**
+ * tighten_guest_free_page_bmap - process the free page bitmap from
+ *         guest to get a tight page bitmap which does not contain
+ *         holes.
+ * @bmap: undressed guest free page bitmap
+ * Returns: a tight guest free page bitmap, the n th bit in the
+ *         returned bitmap and the n th bit in the migration bitmap
+ *         should correspond to the same guest RAM page.
+ */
+unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap);
+
+/**
+ * get_guest_max_pfn - get the max pfn of guest
+ * Returns: the max pfn of guest
+ */
+unsigned long get_guest_max_pfn(void);
+
 #ifndef _WIN32
 int kvm_set_signal_mask(CPUState *cpu, const sigset_t *sigset);
 #endif
diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 5c2bd7a..1cfccb3 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c
@@ -626,3 +626,17 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     return (data - 32) & 0xffff;
 }
+
+unsigned long get_guest_max_pfn(void)
+{
+    /* To be done */
+
+    return 0;
+}
+
+unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
+{
+    /* To be done */
+
+    return bmap;
+}
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 9327523..f0503dd 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -3378,3 +3378,40 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     abort();
 }
+
+#define _4G (1ULL << 32)
+
+unsigned long get_guest_max_pfn(void)
+{
+    PCMachineState *pcms = PC_MACHINE(current_machine);
+    ram_addr_t above_4g_mem = pcms->above_4g_mem_size;
+    unsigned long max_pfn;
+
+    if (above_4g_mem) {
+        max_pfn = (_4G + above_4g_mem) >> TARGET_PAGE_BITS;
+    } else {
+        max_pfn = pcms->below_4g_mem_size >> TARGET_PAGE_BITS;
+    }
+
+    return max_pfn;
+}
+
+unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
+{
+    PCMachineState *pcms = PC_MACHINE(current_machine);
+    ram_addr_t above_4g_mem = pcms->above_4g_mem_size;
+
+    if (above_4g_mem) {
+        unsigned long *src, *dst, len, pos;
+        ram_addr_t below_4g_mem = pcms->below_4g_mem_size;
+        src = bmap + (_4G >> TARGET_PAGE_BITS) / BITS_PER_LONG;
+        dst = bmap + (below_4g_mem >> TARGET_PAGE_BITS) / BITS_PER_LONG;
+        bitmap_move(dst, src, above_4g_mem >> TARGET_PAGE_BITS);
+
+        pos = (above_4g_mem + below_4g_mem) >> TARGET_PAGE_BITS;
+        len = (_4G - below_4g_mem) >> TARGET_PAGE_BITS;
+        bitmap_clear(bmap, pos, len);
+    }
+
+    return bmap;
+}
diff --git a/target-mips/kvm.c b/target-mips/kvm.c
index f3f832d..ba39827 100644
--- a/target-mips/kvm.c
+++ b/target-mips/kvm.c
@@ -1047,3 +1047,17 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     abort();
 }
+
+unsigned long get_guest_max_pfn(void)
+{
+    /* To be done */
+
+    return 0;
+}
+
+unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
+{
+    /* To be done */
+
+    return bmap;
+}
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 884d564..ff67b3e 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -2630,3 +2630,17 @@ int kvmppc_enable_hwrng(void)
 
     return kvmppc_enable_hcall(kvm_state, H_RANDOM);
 }
+
+unsigned long get_guest_max_pfn(void)
+{
+    /* To be done */
+
+    return 0;
+}
+
+unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
+{
+    /* To be done */
+
+    return bmap;
+}
diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index 2991bff..2e5c763 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -2271,3 +2271,17 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     abort();
 }
+
+unsigned long get_guest_max_pfn(void)
+{
+    /* To be done */
+
+    return 0;
+}
+
+unsigned long *tighten_guest_free_page_bmap(unsigned long *bmap)
+{
+    /* To be done */
+
+    return bmap;
+}
