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

[Paolo Bonzini <pbonzini@redhat.com>]

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:
 #

I'm not sure if the cpuid-feature field is useful for libvirt and
other management applications.  Eduardo, what do you think?

Thanks,

Paolo