[PATCH v2 1/1] s390/ipl: sync back loadparm

[Halil Pasic <pasic@linux.ibm.com>]

We expose loadparm as a r/w machine property, but if loadparm is set by
the guest via DIAG 308, we don't update the property. Having a
disconnect between the guest view and the QEMU property is not nice in
itself, but things get even worse for SCSI, where under certain
circumstances (see 789b5a401b "s390: Ensure IPL from SCSI works as
expected" for details) we call s390_gen_initial_iplb() on resets
effectively overwriting the guest/user supplied loadparm with the stale
value.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Fixes: 7104bae9de ("hw/s390x: provide loadparm property for the machine")
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Viktor Mihajlovski <mihajlov@linux.ibm.com>
Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
---
v1 --> v2:
* tweaked the Fixes tag (Connie)
* s/mo/machine/ (David)
* We decided to not abort if the setter fails. It is not clear where
  do the validation logic come from in the first place. For now lets put
  out a warning if things go wrong.
  The warning we get looks something like:
  qemu-system-s390x: warning: LOADPARM: invalid character '?' (ASCII 0x3f)
* I keept the r-b's and the tested-by as the changes are minor. Please
  shout at me if you object.
---
 hw/s390x/ipl.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index 9c1ecd423c..8bd50de44c 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -538,6 +538,30 @@ static bool is_virtio_scsi_device(IplParameterBlock *iplb)
     return is_virtio_ccw_device_of_type(iplb, VIRTIO_ID_SCSI);
 }
 
+static void update_machine_ipl_properties(IplParameterBlock *iplb)
+{
+    Object *machine = qdev_get_machine();
+    Error *err = NULL;
+
+    /* Sync loadparm */
+    if (iplb->flags & DIAG308_FLAGS_LP_VALID) {
+        char ascii_loadparm[8];
+        int i;
+        uint8_t *ebcdic_loadparm = iplb->loadparm;
+
+        for (i = 0; i < 8 && ebcdic_loadparm[i]; i++) {
+            ascii_loadparm[i] = ebcdic2ascii[(uint8_t) ebcdic_loadparm[i]];
+        }
+        ascii_loadparm[i] = 0;
+        object_property_set_str(machine, ascii_loadparm, "loadparm", &err);
+    } else {
+        object_property_set_str(machine, "", "loadparm", &err);
+    }
+    if (err) {
+        warn_report_err(err);
+    }
+}
+
 void s390_ipl_update_diag308(IplParameterBlock *iplb)
 {
     S390IPLState *ipl = get_ipl_device();
@@ -545,6 +569,7 @@ void s390_ipl_update_diag308(IplParameterBlock *iplb)
     ipl->iplb = *iplb;
     ipl->iplb_valid = true;
     ipl->netboot = is_virtio_net_device(iplb);
+    update_machine_ipl_properties(iplb);
 }
 
 IplParameterBlock *s390_ipl_get_iplb(void)

base-commit: 67f17e23baca5dd545fe98b01169cc351a70fe35
-- 
2.17.1