[PATCH v4 3/4] s390x/css: Refactor IRB construction

[Eric Farman <farman@linux.ibm.com>]

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>
---
 hw/s390x/3270-ccw.c    |  1 +
 hw/s390x/css.c         | 45 +++++++++++++++++++++++++++---------------
 hw/s390x/virtio-ccw.c  |  1 +
 include/hw/s390x/css.h |  2 ++
 4 files changed, 33 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 a54e384566..736715e100 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;
diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
index bba7593d2e..7c23a13f3d 100644
--- a/include/hw/s390x/css.h
+++ b/include/hw/s390x/css.h
@@ -138,6 +138,7 @@ struct SubchDev {
     int (*ccw_cb) (SubchDev *, CCW1);
     void (*disable_cb)(SubchDev *);
     IOInstEnding (*do_subchannel_work) (SubchDev *);
+    void (*irb_cb)(SubchDev *, IRB *);
     SenseId id;
     void *driver_data;
 };
@@ -215,6 +216,7 @@ void css_clear_sei_pending(void);
 IOInstEnding s390_ccw_cmd_request(SubchDev *sch);
 IOInstEnding do_subchannel_work_virtual(SubchDev *sub);
 IOInstEnding do_subchannel_work_passthrough(SubchDev *sub);
+void build_irb_virtual(SubchDev *sch, IRB *irb);
 
 int s390_ccw_halt(SubchDev *sch);
 int s390_ccw_clear(SubchDev *sch);
-- 
2.25.1