[libvirt PATCH v2 01/20] cpu_x86: Simplify x86ParseCPUID

[Michal Prívozník]

On 11/4/21 5:27 PM, Tim Wiederhake wrote:
> ... by using virXMLProp*() helpers. These only require a xmlNodePtr and
> do not need a xmlXPathContextPtr. Reflect that in the function signature.
> 
> Signed-off-by: Tim Wiederhake <twiederh at redhat.com>
> ---
>  src/cpu/cpu_x86.c | 43 +++++++++++++++++--------------------------
>  1 file changed, 17 insertions(+), 26 deletions(-)
> 
> diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
> index 1b829e5658..b0f6fa8f34 100644
> --- a/src/cpu/cpu_x86.c
> +++ b/src/cpu/cpu_x86.c
> @@ -1021,37 +1021,28 @@ x86FeatureNames(virCPUx86Map *map,
>  
>  
>  static int
> -x86ParseCPUID(xmlXPathContextPtr ctxt,
> +x86ParseCPUID(xmlNodePtr node,
>                virCPUx86DataItem *item)
>  {
> -    virCPUx86CPUID *cpuid;
> -    unsigned long eax_in, ecx_in;
> -    unsigned long eax, ebx, ecx, edx;
> -    int ret_eax_in, ret_ecx_in, ret_eax, ret_ebx, ret_ecx, ret_edx;
> -
> -    memset(item, 0, sizeof(*item));
> +    virCPUx86CPUID cpuid;
>  
> -    eax_in = ecx_in = 0;
> -    eax = ebx = ecx = edx = 0;
> -    ret_eax_in = virXPathULongHex("string(@eax_in)", ctxt, &eax_in);
> -    ret_ecx_in = virXPathULongHex("string(@ecx_in)", ctxt, &ecx_in);
> -    ret_eax = virXPathULongHex("string(@eax)", ctxt, &eax);
> -    ret_ebx = virXPathULongHex("string(@ebx)", ctxt, &ebx);
> -    ret_ecx = virXPathULongHex("string(@ecx)", ctxt, &ecx);
> -    ret_edx = virXPathULongHex("string(@edx)", ctxt, &edx);
> +    memset(&cpuid, 0, sizeof(cpuid));

Alternatively, let compiler clear the variable out in variable declaration:

    virCPUx86CPUID cpuid = { 0 };


>  
> -    if (ret_eax_in < 0 || ret_ecx_in == -2 ||
> -        ret_eax == -2 || ret_ebx == -2 || ret_ecx == -2 || ret_edx == -2)
> +    if (virXMLPropUInt(node, "eax_in", 0, VIR_XML_PROP_REQUIRED, &cpuid.eax_in) < 0)
> +        return -1;
> +    if (virXMLPropUInt(node, "ecx_in", 0, VIR_XML_PROP_NONE, &cpuid.ecx_in) < 0)
> +        return -1;
> +    if (virXMLPropUInt(node, "eax", 0, VIR_XML_PROP_NONE, &cpuid.eax) < 0)
> +        return -1;
> +    if (virXMLPropUInt(node, "ebx", 0, VIR_XML_PROP_NONE, &cpuid.ebx) < 0)
> +        return -1;
> +    if (virXMLPropUInt(node, "ecx", 0, VIR_XML_PROP_NONE, &cpuid.ecx) < 0)
> +        return -1;
> +    if (virXMLPropUInt(node, "edx", 0, VIR_XML_PROP_NONE, &cpuid.edx) < 0)
>          return -1;
>  
>      item->type = VIR_CPU_X86_DATA_CPUID;
> -    cpuid = &item->data.cpuid;
> -    cpuid->eax_in = eax_in;
> -    cpuid->ecx_in = ecx_in;
> -    cpuid->eax = eax;
> -    cpuid->ebx = ebx;
> -    cpuid->ecx = ecx;
> -    cpuid->edx = edx;
> +    item->data.cpuid = cpuid;
>      return 0;
>  }
>  
> @@ -1122,7 +1113,7 @@ x86FeatureParse(xmlXPathContextPtr ctxt,
>      for (i = 0; i < n; i++) {
>          ctxt->node = nodes[i];
>          if (virXMLNodeNameEqual(nodes[i], "cpuid")) {
> -            if (x86ParseCPUID(ctxt, &item) < 0) {
> +            if (x86ParseCPUID(ctxt->node, &item) < 0) {

I believe nodes[i] can be passed directly. Because in the next patch you
rework the else branch and if that used nodes[i] too then 'ctxt->node =
nodes[i]' line could be dropped.

>                  virReportError(VIR_ERR_INTERNAL_ERROR,
>                                 _("Invalid cpuid[%zu] in %s feature"),
>                                 i, feature->name);
> @@ -1812,7 +1803,7 @@ virCPUx86DataParse(xmlXPathContextPtr ctxt)
>      for (i = 0; i < n; i++) {
>          ctxt->node = nodes[i];
>          if (virXMLNodeNameEqual(nodes[i], "cpuid")) {
> -            if (x86ParseCPUID(ctxt, &item) < 0) {
> +            if (x86ParseCPUID(ctxt->node, &item) < 0) {
>                  virReportError(VIR_ERR_INTERNAL_ERROR,
>                                 _("failed to parse cpuid[%zu]"), i);
>                  return NULL;
> 

Same here. But looking more into the future, doesn't matter really,
because in pach 03/20 you replace all of this with a function and use
xmlNode directly.

Michal