s390x/css: fence off MIDA

MIDA (modified indirect data addressing) is an optional facility, and
we (currently) don't support it. Let's post an operand exception if
the guest tries to set it in the orb and a channel program check
if it is set in a ccw, as specified in the Principles of Operation.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

hw/s390x/css.c

@@ -433,6 +433,11 @@ static int css_interpret_ccw(SubchDev *sch, hwaddr ccw_addr,
         return -EINVAL;
     }
 
+    /* We don't support MIDA. */
+    if (ccw.flags & CCW_FLAG_MIDA) {
+        return -EINVAL;
+    }
+
     if (ccw.flags & CCW_FLAG_SUSPEND) {
         return suspend_allowed ? -EINPROGRESS : -EINVAL;
     }

include/hw/s390x/ioinst.h

@@ -182,6 +182,7 @@ typedef struct CCW1 {
 #define CCW_FLAG_PCI             0x08
 #define CCW_FLAG_IDA             0x04
 #define CCW_FLAG_SUSPEND         0x02
+#define CCW_FLAG_MIDA            0x01
 
 #define CCW_CMD_NOOP             0x03
 #define CCW_CMD_BASIC_SENSE      0x04

target/s390x/ioinst.c

@@ -201,6 +201,10 @@ static int ioinst_orb_valid(ORB *orb)
         (orb->ctrl1 & ORB_CTRL1_MASK_INVALID)) {
         return 0;
     }
+    /* We don't support MIDA. */
+    if (orb->ctrl1 & ORB_CTRL1_MASK_MIDAW) {
+        return 0;
+    }
     if ((orb->cpa & HIGH_ORDER_BIT) != 0) {
         return 0;
     }