s390: use correct input data address for setup_randomness

commit 4920e3cf upstream.

The current implementation of setup_randomness uses the stack address
and therefore the pointer to the SYSIB 3.2.2 block as input data
address. Furthermore the length of the input data is the number of
virtual-machine description blocks which is typically one.

This means that typically a single zero byte is fed to
add_device_randomness.

Fix both of these and use the address of the first virtual machine
description block as input data address and also use the correct
length.

Fixes: bcfcbb6b ("s390: add system information as device randomness")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/s390/kernel/setup.c

@@ -821,7 +821,7 @@ static void __init setup_randomness(void)
 
 	vmms = (struct sysinfo_3_2_2 *) memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 	if (stsi(vmms, 3, 2, 2) == 0 && vmms->count)
-		add_device_randomness(&vmms, vmms->count);
+		add_device_randomness(&vmms->vm, sizeof(vmms->vm[0]) * vmms->count);
 	memblock_free((unsigned long) vmms, PAGE_SIZE);
 }