Re: [PATCH 2/9] target/ppc: add errp to kvmppc_read_int_cpu_dt()

[Cédric Le Goater]

On 6/30/22 21:42, Daniel Henrique Barboza wrote:

The function can't just 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 <danielhb...@gmail.com>
---
  target/ppc/kvm.c | 16 +++++++++-------
  1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 109823136d..bc17437097 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -1925,15 +1925,17 @@ static uint64_t kvmppc_read_int_dt(const char *filename)

/*

   * 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))) {

+        error_setg(errp, "Failed to read CPU property %s", propname);
          return 0;
      }

@@ -1946,12 +1948,12 @@ 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);

This should be fatal. no ?

C.

  }

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;
@@ -2336,8 +2338,8 @@ 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();