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>

3 files changed, 31 insertions, 16 deletions

diff --git a/hw/s390x/3270-ccw.c b/hw/s390x/3270-ccw.c
index 13e93d8d8f..69e6783ade 100644
--- a/hw/s390x/3270-ccw.c
+++ b/hw/s390x/3270-ccw.c
@@ -129,6 +129,7 @@ static void emulated_ccw_3270_realize(DeviceState *ds, Error **errp)
                                 EMULATED_CCW_3270_CHPID_TYPE);
     sch->do_subchannel_work = do_subchannel_work_virtual;
     sch->ccw_cb = emulated_ccw_3270_cb;
+    sch->irb_cb = build_irb_virtual;
 
     ck->init(dev, &err);
     if (err) {
diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 26bd01458f..1a3aad5163 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);
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 220b9efcf9..d68888fccd 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -753,6 +753,7 @@ static void virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
     sch->id.reserved = 0xff;
     sch->id.cu_type = VIRTIO_CCW_CU_TYPE;
     sch->do_subchannel_work = do_subchannel_work_virtual;
+    sch->irb_cb = build_irb_virtual;
     ccw_dev->sch = sch;
     dev->indicators = NULL;
     dev->revision = -1;