s390x: refactor error handling for MSCH handler

Simplify the error handling of the MSCH.  Let the code detecting the
condition tell (in a less ambiguous way) how it's to be handled. No
changes in behavior.
Signed-off-by: NHalil Pasic <pasic@linux.vnet.ibm.com>
Message-Id: <20171017140453.51099-8-pasic@linux.vnet.ibm.com>
[CH: fix return code for fctl != 0]
Reviewed-by: NDong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cohuck@redhat.com>

hw/s390x/css.c

@@ -1347,28 +1347,24 @@ static void copy_schib_from_guest(SCHIB *dest, const SCHIB *src)
     }
 }
 
-int css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
+IOInstEnding css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
 {
     SCSW *s = &sch->curr_status.scsw;
     PMCW *p = &sch->curr_status.pmcw;
     uint16_t oldflags;
-    int ret;
     SCHIB schib;
 
     if (!(sch->curr_status.pmcw.flags & PMCW_FLAGS_MASK_DNV)) {
-        ret = 0;
-        goto out;
+        return IOINST_CC_EXPECTED;
     }
 
     if (s->ctrl & SCSW_STCTL_STATUS_PEND) {
-        ret = -EINPROGRESS;
-        goto out;
+        return IOINST_CC_STATUS_PRESENT;
     }
 
     if (s->ctrl &
         (SCSW_FCTL_START_FUNC|SCSW_FCTL_HALT_FUNC|SCSW_FCTL_CLEAR_FUNC)) {
-        ret = -EBUSY;
-        goto out;
+        return IOINST_CC_BUSY;
     }
 
     copy_schib_from_guest(&schib, orig_schib);
@@ -1395,11 +1391,7 @@ int css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
         && (p->flags & PMCW_FLAGS_MASK_ENA) == 0) {
         sch->disable_cb(sch);
     }
-
-    ret = 0;
-
-out:
-    return ret;
+    return IOINST_CC_EXPECTED;
 }
 
 IOInstEnding css_do_xsch(SubchDev *sch)

include/hw/s390x/css.h

@@ -239,7 +239,7 @@ bool css_subch_visible(SubchDev *sch);
 void css_conditional_io_interrupt(SubchDev *sch);
 int css_do_stsch(SubchDev *sch, SCHIB *schib);
 bool css_schid_final(int m, uint8_t cssid, uint8_t ssid, uint16_t schid);
-int css_do_msch(SubchDev *sch, const SCHIB *schib);
+IOInstEnding css_do_msch(SubchDev *sch, const SCHIB *schib);
 IOInstEnding css_do_xsch(SubchDev *sch);
 IOInstEnding css_do_csch(SubchDev *sch);
 IOInstEnding css_do_hsch(SubchDev *sch);

target/s390x/ioinst.c

@@ -111,8 +111,6 @@ void ioinst_handle_msch(S390CPU *cpu, uint64_t reg1, uint32_t ipb)
     SubchDev *sch;
     SCHIB schib;
     uint64_t addr;
-    int ret = -ENODEV;
-    int cc;
     CPUS390XState *env = &cpu->env;
     uint8_t ar;
 
@@ -131,24 +129,11 @@ void ioinst_handle_msch(S390CPU *cpu, uint64_t reg1, uint32_t ipb)
     }
     trace_ioinst_sch_id("msch", cssid, ssid, schid);
     sch = css_find_subch(m, cssid, ssid, schid);
-    if (sch && css_subch_visible(sch)) {
-        ret = css_do_msch(sch, &schib);
-    }
-    switch (ret) {
-    case -ENODEV:
-        cc = 3;
-        break;
-    case -EBUSY:
-        cc = 2;
-        break;
-    case 0:
-        cc = 0;
-        break;
-    default:
-        cc = 1;
-        break;
+    if (!sch || !css_subch_visible(sch)) {
+        setcc(cpu, 3);
+        return;
     }
-    setcc(cpu, cc);
+    setcc(cpu, css_do_msch(sch, &schib));
 }
 
 static void copy_orb_from_guest(ORB *dest, const ORB *src)