[Qemu-devel] [PATCH qom-cpu 6/9] target-i386: Add "feature-words" property

[Eduardo Habkost <ehabkost@redhat.com>]

This property will be useful for libvirt, as libvirt already has logic
based on low-level feature bits (not feature names), so it will be
really easy to convert the current libvirt logic to something using the
"feature-words" property.

The property will have two main use cases:
 - Checking host capabilities, by checking the features of the "host"
   CPU model
 - Checking which features are enabled on each CPU model

Example output:

  $ ./QMP/qmp --path=/tmp/m qom-get --path=/machine/unattached/device[1] --property=feature-words
  item[0].cpuid-register: EDX
  item[0].cpuid-input-eax: 2147483658
  item[0].features: 0
  item[1].cpuid-register: EAX
  item[1].cpuid-input-eax: 1073741825
  item[1].features: 0
  item[2].cpuid-register: EDX
  item[2].cpuid-input-eax: 3221225473
  item[2].features: 0
  item[3].cpuid-register: ECX
  item[3].cpuid-input-eax: 2147483649
  item[3].features: 101
  item[4].cpuid-register: EDX
  item[4].cpuid-input-eax: 2147483649
  item[4].features: 563346425
  item[5].cpuid-register: EBX
  item[5].cpuid-input-eax: 7
  item[5].features: 0
  item[5].cpuid-input-ecx: 0
  item[6].cpuid-register: ECX
  item[6].cpuid-input-eax: 1
  item[6].features: 2155880449
  item[7].cpuid-register: EDX
  item[7].cpuid-input-eax: 1
  item[7].features: 126614521

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
 * Merge the non-qapi and qapi patches, to keep series simpler
 * Use the feature word array series as base, so we don't have
   to set the feature word values one-by-one in the code
 * Change type name of property from "x86-cpu-feature-words" to
   "X86CPUFeatureWordInfo"
 * Remove cpu-qapi-schema.json and simply add the type definitions
   to qapi-schema.json, to keep the changes simpler
   * This required compiling qapi-types.o and qapi-visit.o into
     *-user as well
---
 .gitignore        |  2 ++
 Makefile.objs     |  7 +++++-
 qapi-schema.json  | 31 ++++++++++++++++++++++++
 target-i386/cpu.c | 70 +++++++++++++++++++++++++++++++++++++++++++++----------
 4 files changed, 97 insertions(+), 13 deletions(-)

diff --git a/.gitignore b/.gitignore
index 487813a..71408e3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,6 +21,8 @@ linux-headers/asm
 qapi-generated
 qapi-types.[ch]
 qapi-visit.[ch]
+cpu-qapi-types.[ch]
+cpu-qapi-visit.[ch]
 qmp-commands.h
 qmp-marshal.c
 qemu-doc.html
diff --git a/Makefile.objs b/Makefile.objs
index a473348..1835d37 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -78,10 +78,15 @@ common-obj-$(CONFIG_SMARTCARD_NSS) += $(libcacard-y)
 ######################################################################
 # qapi
 
-common-obj-y += qmp-marshal.o qapi-visit.o qapi-types.o
+common-obj-y += qmp-marshal.o
 common-obj-y += qmp.o hmp.o
 endif
 
+######################################################################
+# some qapi visitors are used by both system and user emulation:
+
+common-obj-y += qapi-visit.o qapi-types.o
+
 #######################################################################
 # Target-independent parts used in system and user emulation
 common-obj-y += qemu-log.o
diff --git a/qapi-schema.json b/qapi-schema.json
index 751d3c2..424434f 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3505,3 +3505,34 @@
     '*asl_compiler_rev':  'uint32',
     '*file':              'str',
     '*data':              'str' }}
+
+# @X86CPURegister32
+#
+# A X86 32-bit register
+#
+# Since: 1.5
+##
+{ 'enum': 'X86CPURegister32',
+  'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ] }
+
+##
+# @X86CPUFeatureWordInfo
+#
+# Information about a X86 CPU feature word
+#
+# @cpuid-input-eax: Input EAX value for CPUID instruction for that feature word
+#
+# @cpuid-input-ecx: #optional Input ECX value for CPUID instruction for that
+#                   feature word
+#
+# @cpuid-register: Output register containing the feature bits
+#
+# @features: value of output register, containing the feature bits
+#
+# Since: 1.5
+##
+{ 'type': 'X86CPUFeatureWordInfo',
+  'data': { 'cpuid-input-eax': 'int',
+            '*cpuid-input-ecx': 'int',
+            'cpuid-register': 'X86CPURegister32',
+            'features': 'int' } }
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 314931e..757749c 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -30,6 +30,8 @@
 #include "qemu/config-file.h"
 #include "qapi/qmp/qerror.h"
 
+#include "qapi-types.h"
+#include "qapi-visit.h"
 #include "qapi/visitor.h"
 #include "sysemu/arch_init.h"
 
@@ -194,23 +196,34 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
     },
 };
 
+typedef struct X86RegisterInfo32 {
+    /* Name of register */
+    const char *name;
+    /* QAPI enum value register */
+    X86CPURegister32 qapi_enum;
+} X86RegisterInfo32;
+
+#define REGISTER(reg) \
+    [R_##reg] = { .name = #reg, .qapi_enum = X86_C_P_U_REGISTER32_##reg }
+X86RegisterInfo32 x86_reg_info_32[CPU_NB_REGS32] = {
+    REGISTER(EAX),
+    REGISTER(ECX),
+    REGISTER(EDX),
+    REGISTER(EBX),
+    REGISTER(ESP),
+    REGISTER(EBP),
+    REGISTER(ESI),
+    REGISTER(EDI),
+};
+#undef REGISTER
+
+
 const char *get_register_name_32(unsigned int reg)
 {
-    static const char *reg_names[CPU_NB_REGS32] = {
-        [R_EAX] = "EAX",
-        [R_ECX] = "ECX",
-        [R_EDX] = "EDX",
-        [R_EBX] = "EBX",
-        [R_ESP] = "ESP",
-        [R_EBP] = "EBP",
-        [R_ESI] = "ESI",
-        [R_EDI] = "EDI",
-    };
-
     if (reg > CPU_NB_REGS32) {
         return NULL;
     }
-    return reg_names[reg];
+    return x86_reg_info_32[reg].name;
 }
 
 /* collects per-function cpuid data
@@ -1360,6 +1373,36 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
     cpu->env.tsc_khz = value / 1000;
 }
 
+static void x86_cpu_get_feature_words(Object *obj, Visitor *v, void *opaque,
+                                   const char *name, Error **errp)
+{
+    X86CPU *cpu = X86_CPU(obj);
+    CPUX86State *env = &cpu->env;
+    FeatureWord w;
+    Error *err = NULL;
+    X86CPUFeatureWordInfo word_infos[FEATURE_WORDS] = { };
+    X86CPUFeatureWordInfoList list_entries[FEATURE_WORDS] = { };
+    X86CPUFeatureWordInfoList *list = NULL;
+
+    for (w = 0; w < FEATURE_WORDS; w++) {
+        FeatureWordInfo *wi = &feature_word_info[w];
+        X86CPUFeatureWordInfo *qwi = &word_infos[w];
+        qwi->cpuid_input_eax = wi->cpuid_eax;
+        qwi->has_cpuid_input_ecx = wi->cpuid_needs_ecx;
+        qwi->cpuid_input_ecx = wi->cpuid_ecx;
+        qwi->cpuid_register = x86_reg_info_32[wi->cpuid_reg].qapi_enum;
+        qwi->features = env->features[w];
+
+        /* List will be in reverse order, but order shouldn't matter */
+        list_entries[w].next = list;
+        list_entries[w].value = &word_infos[w];
+        list = &list_entries[w];
+    }
+
+    visit_type_X86CPUFeatureWordInfoList(v, &list, "feature-words", &err);
+    error_propagate(errp, err);
+}
+
 static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *name)
 {
     x86_def_t *def;
@@ -2348,6 +2391,9 @@ static void x86_cpu_initfn(Object *obj)
     object_property_add(obj, "tsc-frequency", "int",
                         x86_cpuid_get_tsc_freq,
                         x86_cpuid_set_tsc_freq, NULL, NULL, NULL);
+    object_property_add(obj, "feature-words", "X86CPUFeatureWordInfo",
+                        x86_cpu_get_feature_words,
+                        NULL, NULL, NULL, NULL);
 
     env->cpuid_apic_id = x86_cpu_apic_id_from_index(cs->cpu_index);
 
-- 
1.8.1.4