s390x/css: Refactor IRB construction

Currently, all subchannel types have "sense data" copied into
the IRB.ECW space, and a couple flags enabled in the IRB.SCSW
and IRB.ESW. But for passthrough (vfio-ccw) subchannels,
this data isn't populated in the first place, so enabling
those flags leads to unexpected behavior if the guest tries to
process the sense data (zeros) in the IRB.ECW.

Let's add a subchannel callback that builds these portions of
the IRB, and move the existing code into a routine for those
virtual subchannels. The passthrough subchannels will be able
to piggy-back onto this later.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20210617232537.1337506-4-farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

1 files changed, 29 insertions, 16 deletions

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 26bd014..1a3aad5 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -1650,6 +1650,30 @@ static void build_irb_sense_data(SubchDev *sch, IRB *irb)
     }
 }
 
+void build_irb_virtual(SubchDev *sch, IRB *irb)
+{
+    SCHIB *schib = &sch->curr_status;
+    uint16_t stctl = schib->scsw.ctrl & SCSW_CTRL_MASK_STCTL;
+
+    if (stctl & SCSW_STCTL_STATUS_PEND) {
+        if (schib->scsw.cstat & (SCSW_CSTAT_DATA_CHECK |
+                        SCSW_CSTAT_CHN_CTRL_CHK |
+                        SCSW_CSTAT_INTF_CTRL_CHK)) {
+            irb->scsw.flags |= SCSW_FLAGS_MASK_ESWF;
+            irb->esw.word0 = 0x04804000;
+        } else {
+            irb->esw.word0 = 0x00800000;
+        }
+        /* If a unit check is pending, copy sense data. */
+        if ((schib->scsw.dstat & SCSW_DSTAT_UNIT_CHECK) &&
+            (schib->pmcw.chars & PMCW_CHARS_MASK_CSENSE)) {
+            irb->scsw.flags |= SCSW_FLAGS_MASK_ESWF | SCSW_FLAGS_MASK_ECTL;
+            build_irb_sense_data(sch, irb);
+            irb->esw.erw = ESW_ERW_SENSE | (sizeof(sch->sense_data) << 8);
+        }
+    }
+}
+
 int css_do_tsch_get_irb(SubchDev *sch, IRB *target_irb, int *irb_len)
 {
     SCHIB *schib = &sch->curr_status;
@@ -1668,23 +1692,12 @@ int css_do_tsch_get_irb(SubchDev *sch, IRB *target_irb, int *irb_len)
 
     /* Copy scsw from current status. */
     irb.scsw = schib->scsw;
-    if (stctl & SCSW_STCTL_STATUS_PEND) {
-        if (schib->scsw.cstat & (SCSW_CSTAT_DATA_CHECK |
-                        SCSW_CSTAT_CHN_CTRL_CHK |
-                        SCSW_CSTAT_INTF_CTRL_CHK)) {
-            irb.scsw.flags |= SCSW_FLAGS_MASK_ESWF;
-            irb.esw.word0 = 0x04804000;
-        } else {
-            irb.esw.word0 = 0x00800000;
-        }
-        /* If a unit check is pending, copy sense data. */
-        if ((schib->scsw.dstat & SCSW_DSTAT_UNIT_CHECK) &&
-            (schib->pmcw.chars & PMCW_CHARS_MASK_CSENSE)) {
-            irb.scsw.flags |= SCSW_FLAGS_MASK_ESWF | SCSW_FLAGS_MASK_ECTL;
-            build_irb_sense_data(sch, &irb);
-            irb.esw.erw = ESW_ERW_SENSE | (sizeof(sch->sense_data) << 8);
-        }
+
+    /* Build other IRB data, if necessary */
+    if (sch->irb_cb) {
+        sch->irb_cb(sch, &irb);
     }
+
     /* Store the irb to the guest. */
     p = schib->pmcw;
     copy_irb_to_guest(target_irb, &irb, &p, irb_len);