s390x/sclp: fix maxram calculation

We clamp down ram_size to match the sclp increment size. We do
not do the same for maxram_size, which means for large guests
with some sizes (e.g. -m 50000) maxram_size differs from ram_size.
This can break other code (e.g. CMMA migration) which uses maxram_size
to calculate the number of pages and then throws some errors.

Fixes: 82fab5c5 ("s390x/sclp: remove memory hotplug support")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
CC: qemu-stable@nongnu.org
CC: David Hildenbrand <david@redhat.com>
Message-Id: <1532959766-53343-1-git-send-email-borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

hw/s390x/sclp.c

@@ -320,6 +320,7 @@ static void sclp_memory_init(SCLPDevice *sclp)
     initial_mem = initial_mem >> increment_size << increment_size;
 
     machine->ram_size = initial_mem;
+    machine->maxram_size = initial_mem;
     /* let's propagate the changed ram size into the global variable. */
     ram_size = initial_mem;
 }