Re: [Qemu-devel] [PATCH v3 3/3] Change other funcitons referring to feature_word_info[]

[Robert Hoo <robert.hu@linux.intel.com>]

On Fri, 2018-08-17 at 17:52 +0200, Paolo Bonzini wrote:
> On 10/08/2018 16:06, Robert Hoo wrote:
> > x86_cpu_get_feature_words(): limit to CPUID_FEATURE_WORD only.
> 
> This should also grow support for MSR feature words.
> 
> My suggestion is that you add another patch after patch 1 that expands
> the definition of X86CPUFeatureWordInfo like this, and adjusts
> x86_cpu_get_feature_words() to match the new C structs.  Then this
> patch can add MSR feature support somewhat easily.
> 
> The QAPI definitions would then look like this:
> 
> diff --git a/qapi/misc.json b/qapi/misc.json
> index d450cfef21..eae9243976 100644
> --- a/qapi/misc.json
> +++ b/qapi/misc.json
> @@ -2663,9 +2663,9 @@
>    'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ] }
>  
>  ##
> -# @X86CPUFeatureWordInfo:
> +# @X86CPUIDFeatureWordInfo:
>  #
> -# Information about a X86 CPU feature word
> +# Information about an X86 CPUID feature word
>  #
>  # @cpuid-input-eax: Input EAX value for CPUID instruction for that feature word
>  #
> @@ -2678,12 +2690,45 @@
>  #
>  # Since: 1.5
>  ##
> -{ 'struct': 'X86CPUFeatureWordInfo',
> +{ 'struct': 'X86CPUIDFeatureWordInfo',
>    'data': { 'cpuid-input-eax': 'int',
>              '*cpuid-input-ecx': 'int',
>              'cpuid-register': 'X86CPURegister32',
>              'features': 'int' } }
>  
> +##
> +# @X86MSRFeatureWordInfo:
> +#
> +# Information about an X86 MSR feature word
> +#
> +# @index: Index of the model specific register
> +#
> +# @cpuid-feature: CPUID feature name that communicates the existance of the MSR
> +#
> +# @features: value of output register, containing the feature bits
> +#
> +# Since: 3.1
> +##
> +{ 'struct': 'X86MSRFeatureWordInfo',
> +  'data': { 'index': 'int',
> +            'cpuid-feature': 'str',
> +            'features': 'int' } }
> +
> +##
> +# @X86CPUFeatureWordInfo:
> +#
> +# A discriminated record of X86 CPU feature words
> +#
> +# Since: 3.1
> +##
> +
> +{ 'union': 'X86CPUFeatureWordInfo',
> +  'base': { 'type': 'X86CPUFeatureWordType' },
> +  'discriminator': 'type',
> +  'data': {
> +    'cpuid': 'X86CPUIDFeatureWordInfo',
> +    'msr': 'X86MSRFeatureWordInfo' }}
> +
>  ##
>  # @DummyForceArrays:
>  #

[root@robert-ivt qemu]# git diff qapi/misc.json
diff --git a/qapi/misc.json b/qapi/misc.json
index d450cfe..7351dc2 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -2663,25 +2663,25 @@
   'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ] }
 
 ##
-# @X86CPUFeatureWordInfo:
+# @X86CPUIDFeatureWordInfo:
 #
-# Information about a X86 CPU feature word
+# Information about a X86 CPUID feature word
 #
-# @cpuid-input-eax: Input EAX value for CPUID instruction for that
feature word
+# @input-eax: Input EAX value for CPUID instruction for that feature
word
 #
-# @cpuid-input-ecx: Input ECX value for CPUID instruction for that
+# @input-ecx: Input ECX value for CPUID instruction for that
 #                   feature word
 #
-# @cpuid-register: Output register containing the feature bits
+# @register: Output register containing the feature bits
 #
 # @features: value of output register, containing the feature bits
 #
 # Since: 1.5
 ##
-{ 'struct': 'X86CPUFeatureWordInfo',
-  'data': { 'cpuid-input-eax': 'int',
-            '*cpuid-input-ecx': 'int',
-            'cpuid-register': 'X86CPURegister32',
+{ 'struct': 'X86CPUIDFeatureWordInfo',
+  'data': { 'input-eax': 'int',
+            '*input-ecx': 'int',
+            'register': 'X86CPURegister32',
             'features': 'int' } }
 
 ##
@@ -2694,6 +2694,50 @@
 { 'struct': 'DummyForceArrays',
   'data': { 'unused': ['X86CPUFeatureWordInfo'] } }
 
+##
+# @X86MSRFeatureWordInfo:
+#
+# Information about an X86 MSR feature word
+#
+# @index: Index of the model specific register
+#
+# @cpuid-feature: CPUID feature name that communicates the existance of
the MSR
+#
+# @features: value of output register, containing the feature bits
+#
+# Since: 3.1
+##
+{ 'struct': 'X86MSRFeatureWordInfo',
+  'data': { 'index': 'int',
+            'cpuid-feature': 'str',
+            'features': 'int' } }
+
+##
+# @X86CPUFeatureWordType:
+#
+# Kinds of X86 CPU feature words
+#
+# @cpuid: A CPUID leaf
+#
+# @msr: An MSR
+##
+{ 'enum': 'X86CPUFeatureWordType',
+  'data': [ 'cpuid', 'msr' ] }
+
+##
+# @X86CPUFeatureWordInfo:
+#
+# A discriminated record of X86 CPU feature words
+#
+# Since: 3.1
+##
+{ 'union': 'X86CPUFeatureWordInfo',
+  'base': { 'type': 'X86CPUFeatureWordType' },
+  'discriminator': 'type',
+  'data': {
+    'cpuid': 'X86CPUIDFeatureWordInfo',
+    'msr': 'X86MSRFeatureWordInfo' }}
+
 
 ##
 # @NumaOptionsType:

Hi Paolo,

above is my draft change on the qapi json file. 1 question: 
struct X86MSRFeatureWordInfo {
    int64_t index;
    char *cpuid_feature;
    int64_t features;
};
how to have a "const" prefix the "char *"?
> 
> I'm not sure if the cpuid-feature field is useful for libvirt and
> other management applications.  Eduardo, what do you think?
> 
> Thanks,
> 
> Paolo