[PATCH v4 1/4] s390x/css: Introduce an ESW struct

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

The Interrupt Response Block is comprised of several other
structures concatenated together, but only the 12-byte
Subchannel-Status Word (SCSW) is defined as a proper struct.
Everything else is a simple array of 32-bit words.

Let's define a proper struct for the 20-byte Extended-Status
Word (ESW) so that we can make good decisions about the sense
data that would go into the ECW area for virtual vs
passthrough devices.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 hw/s390x/css.c            | 19 +++++++++++++------
 include/hw/s390x/ioinst.h | 12 +++++++++++-
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index bed46f5ec3..59d935570e 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -1335,6 +1335,14 @@ static void copy_schib_to_guest(SCHIB *dest, const SCHIB *src)
     }
 }
 
+static void copy_esw_to_guest(ESW *dest, const ESW *src)
+{
+    dest->word0 = cpu_to_be32(src->word0);
+    dest->erw = cpu_to_be32(src->erw);
+    dest->f_addr = cpu_to_be64(src->f_addr);
+    dest->s_addr = cpu_to_be32(src->s_addr);
+}
+
 IOInstEnding css_do_stsch(SubchDev *sch, SCHIB *schib)
 {
     int ret;
@@ -1604,9 +1612,8 @@ static void copy_irb_to_guest(IRB *dest, const IRB *src, const PMCW *pmcw,
 
     copy_scsw_to_guest(&dest->scsw, &src->scsw);
 
-    for (i = 0; i < ARRAY_SIZE(dest->esw); i++) {
-        dest->esw[i] = cpu_to_be32(src->esw[i]);
-    }
+    copy_esw_to_guest(&dest->esw, &src->esw);
+
     for (i = 0; i < ARRAY_SIZE(dest->ecw); i++) {
         dest->ecw[i] = cpu_to_be32(src->ecw[i]);
     }
@@ -1655,9 +1662,9 @@ int css_do_tsch_get_irb(SubchDev *sch, IRB *target_irb, int *irb_len)
                         SCSW_CSTAT_CHN_CTRL_CHK |
                         SCSW_CSTAT_INTF_CTRL_CHK)) {
             irb.scsw.flags |= SCSW_FLAGS_MASK_ESWF;
-            irb.esw[0] = 0x04804000;
+            irb.esw.word0 = 0x04804000;
         } else {
-            irb.esw[0] = 0x00800000;
+            irb.esw.word0 = 0x00800000;
         }
         /* If a unit check is pending, copy sense data. */
         if ((schib->scsw.dstat & SCSW_DSTAT_UNIT_CHECK) &&
@@ -1670,7 +1677,7 @@ int css_do_tsch_get_irb(SubchDev *sch, IRB *target_irb, int *irb_len)
             for (i = 0; i < ARRAY_SIZE(irb.ecw); i++) {
                 irb.ecw[i] = be32_to_cpu(irb.ecw[i]);
             }
-            irb.esw[1] = 0x01000000 | (sizeof(sch->sense_data) << 8);
+            irb.esw.erw = ESW_ERW_SENSE | (sizeof(sch->sense_data) << 8);
         }
     }
     /* Store the irb to the guest. */
diff --git a/include/hw/s390x/ioinst.h b/include/hw/s390x/ioinst.h
index c6737a30d4..e7ab401781 100644
--- a/include/hw/s390x/ioinst.h
+++ b/include/hw/s390x/ioinst.h
@@ -123,10 +123,20 @@ typedef struct SCHIB {
     uint8_t mda[4];
 } QEMU_PACKED SCHIB;
 
+/* format-0 extended-status word */
+typedef struct ESW {
+   uint32_t word0;
+   uint32_t erw;
+   uint64_t f_addr;     /* Zeros for other ESW formats */
+   uint32_t s_addr;     /* Zeros for other ESW formats */
+} QEMU_PACKED ESW;
+
+#define ESW_ERW_SENSE 0x01000000
+
 /* interruption response block */
 typedef struct IRB {
     SCSW scsw;
-    uint32_t esw[5];
+    ESW esw;
     uint32_t ecw[8];
     uint32_t emw[8];
 } IRB;
-- 
2.25.1