diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 54864c259c5e..c24c869e7703 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -126,12 +126,11 @@
 /*
  * KVM does only support memory slots up to KVM_MEM_MAX_NR_PAGES pages
  * as the dirty bitmap must be managed by bitops that take an int as
- * position indicator. If we have a guest beyond that we will split off
- * new subregions. The split must happen on a segment boundary (1MB).
+ * position indicator. This would end at an unaligned  address
+ * (0x7fffff00000). As future variants might provide larger pages
+ * and to make all addresses properly aligned, let us split at 4TB.
  */
-#define KVM_MEM_MAX_NR_PAGES ((1ULL << 31) - 1)
-#define SEG_MSK (~0xfffffULL)
-#define KVM_SLOT_MAX_BYTES ((KVM_MEM_MAX_NR_PAGES * TARGET_PAGE_SIZE) & SEG_MSK)
+#define KVM_SLOT_MAX_BYTES (4UL * TiB)
 
 static CPUWatchpoint hw_watchpoint;
 /*