diff --git a/hw/s390x/s390-stattrib-kvm.c b/hw/s390x/s390-stattrib-kvm.c
index 480551c3db..c7e1f35524 100644
--- a/hw/s390x/s390-stattrib-kvm.c
+++ b/hw/s390x/s390-stattrib-kvm.c
@@ -105,7 +105,8 @@ static void kvm_s390_stattrib_synchronize(S390StAttribState *sa)
     KVMS390StAttribState *sas = KVM_S390_STATTRIB(sa);
     MachineState *machine = MACHINE(qdev_get_machine());
     unsigned long max = machine->maxram_size / TARGET_PAGE_SIZE;
-    unsigned long cx, len = 1 << 19;
+    /* We do not need to reach the maximum buffer size allowed */
+    unsigned long cx, len = KVM_S390_SKEYS_MAX / 2;
     int r;
     struct kvm_s390_cmma_log clog = {
         .flags = 0,
diff --git a/hw/s390x/s390-stattrib.c b/hw/s390x/s390-stattrib.c
index 5161a1659b..766f2015a4 100644
--- a/hw/s390x/s390-stattrib.c
+++ b/hw/s390x/s390-stattrib.c
@@ -21,7 +21,8 @@
 #include "qapi/error.h"
 #include "qapi/qmp/qdict.h"
 
-#define CMMA_BLOCK_SIZE  (1 * KiB)
+/* 512KiB cover 2GB of guest memory */
+#define CMMA_BLOCK_SIZE  (512 * KiB)
 
 #define STATTR_FLAG_EOS     0x01ULL
 #define STATTR_FLAG_MORE    0x02ULL
@@ -203,7 +204,7 @@ static int cmma_save(QEMUFile *f, void *opaque, int final)
     S390StAttribClass *sac = S390_STATTRIB_GET_CLASS(sas);
     uint8_t *buf;
     int r, cx, reallen = 0, ret = 0;
-    uint32_t buflen = 1 << 19;   /* 512kB cover 2GB of guest memory */
+    uint32_t buflen = CMMA_BLOCK_SIZE;
     uint64_t start_gfn = sas->migration_cur_gfn;
 
     buf = g_try_malloc(buflen);