s390x/storage attributes: fix CMMA_BLOCK_SIZE usage

The macro CMMA_BLOCK_SIZE was defined but not used, and a hardcoded
value was instead used in the code.

This patch fixes the value of CMMA_BLOCK_SIZE and uses it in the
appropriate place in the code, and fixes another case of hardcoded
value in the KVM backend, replacing it with the more appropriate
constant KVM_S390_CMMA_SIZE_MAX.
Signed-off-by: NClaudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Message-Id: <1530787170-3101-1-git-send-email-imbrenda@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cohuck@redhat.com>

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,

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);