In preparation for generalizing the custom CSR functionality,
make the test return bool instead of int.  Make the insertion_test
optional, too.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/riscv/th_csr.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/target/riscv/th_csr.c b/target/riscv/th_csr.c
index 6c970d4e813..990453e080e 100644
--- a/target/riscv/th_csr.c
+++ b/target/riscv/th_csr.c
@@ -42,13 +42,9 @@ static RISCVException smode(CPURISCVState *env, int csrno)
     return RISCV_EXCP_ILLEGAL_INST;
 }
 
-static int test_thead_mvendorid(RISCVCPU *cpu)
+static bool test_thead_mvendorid(RISCVCPU *cpu)
 {
-    if (cpu->cfg.mvendorid != THEAD_VENDOR_ID) {
-        return -1;
-    }
-
-    return 0;
+    return cpu->cfg.mvendorid == THEAD_VENDOR_ID;
 }
 
 static RISCVException read_th_sxstatus(CPURISCVState *env, int csrno,
@@ -66,13 +62,12 @@ static riscv_csr th_csr_list[] = {
         .csr_ops = { "th.sxstatus", smode, read_th_sxstatus }
     }
 };
-
 void th_register_custom_csrs(RISCVCPU *cpu)
 {
     for (size_t i = 0; i < ARRAY_SIZE(th_csr_list); i++) {
         int csrno = th_csr_list[i].csrno;
         riscv_csr_operations *csr_ops = &th_csr_list[i].csr_ops;
-        if (!th_csr_list[i].insertion_test(cpu)) {
+        if (!th_csr_list[i].insertion_test || th_csr_list[i].insertion_test(cpu)) {
             riscv_set_csr_ops(csrno, csr_ops);
         }
     }
-- 
2.48.1