s390x/ipl: Extend the IplParameterBlock struct

The IplParameterBlock struct currently has only 200 bytes filled, but it
can be up to 4K.

This patch converts the struct to union with a fully populated struct
inside it and second struct with old values.

For compatibility reasons we disable migration of the extended iplb
field for pre-2.7 machines. Also a guest still can read/write only the
first 200 bytes of IPLB for now.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/target-s390x/misc_helper.c b/target-s390x/misc_helper.c
index 71cbe34e05..fab7f87a8f 100644
--- a/target-s390x/misc_helper.c
+++ b/target-s390x/misc_helper.c
@@ -232,8 +232,8 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3)
             program_interrupt(env, PGM_ADDRESSING, ILEN_LATER_INC);
             return;
         }
-        iplb = g_malloc0(sizeof(struct IplParameterBlock));
-        cpu_physical_memory_read(addr, iplb, sizeof(struct IplParameterBlock));
+        iplb = g_malloc0(sizeof(IplParameterBlock));
+        cpu_physical_memory_read(addr, iplb, S390_IPLB_MIN_CCW_LEN);
         s390_ipl_update_diag308(iplb);
         env->regs[r1 + 1] = DIAG_308_RC_OK;
         g_free(iplb);
@@ -250,8 +250,7 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3)
         }
         iplb = s390_ipl_get_iplb();
         if (iplb) {
-            cpu_physical_memory_write(addr, iplb,
-                                      sizeof(struct IplParameterBlock));
+            cpu_physical_memory_write(addr, iplb, S390_IPLB_MIN_CCW_LEN);
             env->regs[r1 + 1] = DIAG_308_RC_OK;
         } else {
             env->regs[r1 + 1] = DIAG_308_RC_NO_CONF;