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 <danielhb413@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();