[PATCH v3 2/4] target/ppc: enhance error report in kvmppc_read_int_cpu_dt()

[Daniel Henrique Barboza <danielhb413@gmail.com>]

First and foremost, the function can't return '-1' when an error occurs
because the return type is set to uint64_t. Let's fix that.

After that, the function can't simply return 0 whether an error happened
and call it a day. We must provide a way of letting callers know if the
zero return is legitimate or due to an error.

Add an Error pointer to kvmppc_read_int_cpu_dt() that will be filled
with an appropriate error, if one occurs. Callers are then free to pass
an Error pointer and handle it.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 target/ppc/kvm.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 65d136ed5a..cf4610b6fa 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -1926,20 +1926,22 @@ static uint64_t kvmppc_read_int_dt(const char *filename, Error **errp)
 
 /*
  * Read a CPU node property from the host device tree that's a single
- * integer (32-bit or 64-bit).  Returns 0 if anything goes wrong
- * (can't find or open the property, or doesn't understand the format)
+ * integer (32-bit or 64-bit).  Returns 0 and set errp if anything goes
+ * wrong (can't find or open the property, or doesn't understand the
+ * format)
  */
-static uint64_t kvmppc_read_int_cpu_dt(const char *propname)
+static uint64_t kvmppc_read_int_cpu_dt(const char *propname, Error **errp)
 {
     char buf[PATH_MAX], *tmp;
     uint64_t val;
 
     if (kvmppc_find_cpu_dt(buf, sizeof(buf))) {
-        return -1;
+        error_setg(errp, "Failed to read CPU property %s", propname);
+        return 0;
     }
 
     tmp = g_strdup_printf("%s/%s", buf, propname);
-    val = kvmppc_read_int_dt(tmp, NULL);
+    val = kvmppc_read_int_dt(tmp, errp);
     g_free(tmp);
 
     return val;
@@ -1947,12 +1949,12 @@ static uint64_t kvmppc_read_int_cpu_dt(const char *propname)
 
 uint64_t kvmppc_get_clockfreq(void)
 {
-    return kvmppc_read_int_cpu_dt("clock-frequency");
+    return kvmppc_read_int_cpu_dt("clock-frequency", NULL);
 }
 
 static int kvmppc_get_dec_bits(void)
 {
-    int nr_bits = kvmppc_read_int_cpu_dt("ibm,dec-bits");
+    int nr_bits = kvmppc_read_int_cpu_dt("ibm,dec-bits", NULL);
 
     if (nr_bits > 0) {
         return nr_bits;
@@ -2337,8 +2339,8 @@ static void alter_insns(uint64_t *word, uint64_t flags, bool on)
 static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data)
 {
     PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc);
-    uint32_t dcache_size = kvmppc_read_int_cpu_dt("d-cache-size");
-    uint32_t icache_size = kvmppc_read_int_cpu_dt("i-cache-size");
+    uint32_t dcache_size = kvmppc_read_int_cpu_dt("d-cache-size", NULL);
+    uint32_t icache_size = kvmppc_read_int_cpu_dt("i-cache-size", NULL);
 
     /* Now fix up the class with information we can query from the host */
     pcc->pvr = mfpvr();
-- 
2.36.1