Create a function to validate the address parameter of DIAGNOSE.

Refactor the function for reuse in the next patch, which allows address
validation in read or write operation of DIAGNOSE.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
---
 target/s390x/diag.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/target/s390x/diag.c b/target/s390x/diag.c
index a35d808fd7..a347be7633 100644
--- a/target/s390x/diag.c
+++ b/target/s390x/diag.c
@@ -26,6 +26,12 @@
 #include "qemu/error-report.h"
 
 
+static inline bool diag_parm_addr_valid(uint64_t addr, size_t size, bool write)
+{
+    return address_space_access_valid(&address_space_memory, addr,
+                                      size, write, MEMTXATTRS_UNSPECIFIED);
+}
+
 int handle_diag_288(CPUS390XState *env, uint64_t r1, uint64_t r3)
 {
     uint64_t func = env->regs[r1];
@@ -65,9 +71,7 @@ static int diag308_parm_check(CPUS390XState *env, uint64_t r1, uint64_t addr,
         s390_program_interrupt(env, PGM_SPECIFICATION, ra);
         return -1;
     }
-    if (!address_space_access_valid(&address_space_memory, addr,
-                                    sizeof(IplParameterBlock), write,
-                                    MEMTXATTRS_UNSPECIFIED)) {
+    if (!diag_parm_addr_valid(addr, sizeof(IplParameterBlock), write)) {
         s390_program_interrupt(env, PGM_ADDRESSING, ra);
         return -1;
     }
-- 
2.51.1