s390x/pci: move the memory region write from pcistg

Let's move the memory region write from pcistg into a dedicated
function.
This allows us to prepare a later patch searching for subregions
inside of the memory region.
Signed-off-by: NPierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: NYi Min Zhao <zyimin@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1512046530-17773-7-git-send-email-pmorel@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cohuck@redhat.com>

hw/s390x/s390-pci-inst.c

@@ -458,12 +458,27 @@ static int trap_msix(S390PCIBusDevice *pbdev, uint64_t offset, uint8_t pcias)
     }
 }
 
+static MemTxResult zpci_write_bar(S390PCIBusDevice *pbdev, uint8_t pcias,
+                                  uint64_t offset, uint64_t data, uint8_t len)
+{
+    MemoryRegion *mr;
+
+    if (trap_msix(pbdev, offset, pcias)) {
+        offset = offset - pbdev->msix.table_offset;
+        mr = &pbdev->pdev->msix_table_mmio;
+    } else {
+        mr = pbdev->pdev->io_regions[pcias].memory;
+    }
+
+    return memory_region_dispatch_write(mr, offset, data, len,
+                                        MEMTXATTRS_UNSPECIFIED);
+}
+
 int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
 {
     CPUS390XState *env = &cpu->env;
     uint64_t offset, data;
     S390PCIBusDevice *pbdev;
-    MemoryRegion *mr;
     MemTxResult result;
     uint8_t len;
     uint32_t fh;
@@ -523,15 +538,7 @@ int pcistg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
             return 0;
         }
 
-        if (trap_msix(pbdev, offset, pcias)) {
-            offset = offset - pbdev->msix.table_offset;
-            mr = &pbdev->pdev->msix_table_mmio;
-        } else {
-            mr = pbdev->pdev->io_regions[pcias].memory;
-        }
-
-        result = memory_region_dispatch_write(mr, offset, data, len,
-                                     MEMTXATTRS_UNSPECIFIED);
+        result = zpci_write_bar(pbdev, pcias, offset, data, len);
         if (result != MEMTX_OK) {
             s390_program_interrupt(env, PGM_OPERAND, 4, ra);
             return 0;