target-i386: add feature flags for CPUID[EAX=0xd,ECX=1]

These represent xsave-related capabilities of the processor, and KVM may
or may not support them.

Add feature bits so that they are considered by "-cpu ...,enforce", and use
the new feature work instead of calling kvm_arch_get_supported_cpuid.

Bit 3 (XSAVES) is not migratables because it requires saving MSR_IA32_XSS.
Neither KVM nor any commonly available hardware supports it anyway.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target-i386/cpu.c

@@ -274,6 +274,17 @@ static const char *cpuid_apm_edx_feature_name[] = {
     NULL, NULL, NULL, NULL,
 };
 
+static const char *cpuid_xsave_feature_name[] = {
+    "xsaveopt", "xsavec", "xgetbv1", "xsaves",
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+};
+
 #define I486_FEATURES (CPUID_FP87 | CPUID_VME | CPUID_PSE)
 #define PENTIUM_FEATURES (I486_FEATURES | CPUID_DE | CPUID_TSC | \
           CPUID_MSR | CPUID_MCE | CPUID_CX8 | CPUID_MMX | CPUID_APIC)
@@ -391,6 +402,14 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
         .tcg_features = TCG_APM_FEATURES,
         .unmigratable_flags = CPUID_APM_INVTSC,
     },
+    [FEAT_XSAVE] = {
+        .feat_names = cpuid_xsave_feature_name,
+        .cpuid_eax = 0xd,
+        .cpuid_needs_ecx = true, .cpuid_ecx = 1,
+        .cpuid_reg = R_EAX,
+        .tcg_features = 0,
+        .unmigratable_flags = FEAT_XSAVES,
+    },
 };
 
 typedef struct X86RegisterInfo32 {
@@ -1018,6 +1037,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
             CPUID_EXT2_SYSCALL,
         .features[FEAT_8000_0001_ECX] =
             CPUID_EXT3_LAHF_LM,
+        .features[FEAT_XSAVE] =
+            CPUID_XSAVE_XSAVEOPT,
         .xlevel = 0x8000000A,
         .model_id = "Intel Xeon E312xx (Sandy Bridge)",
     },
@@ -1051,6 +1072,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
             CPUID_7_0_EBX_HLE | CPUID_7_0_EBX_AVX2 | CPUID_7_0_EBX_SMEP |
             CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ERMS | CPUID_7_0_EBX_INVPCID |
             CPUID_7_0_EBX_RTM,
+        .features[FEAT_XSAVE] =
+            CPUID_XSAVE_XSAVEOPT,
         .xlevel = 0x8000000A,
         .model_id = "Intel Core Processor (Haswell)",
     },
@@ -1085,6 +1108,8 @@ static X86CPUDefinition builtin_x86_defs[] = {
             CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ERMS | CPUID_7_0_EBX_INVPCID |
             CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_RDSEED | CPUID_7_0_EBX_ADX |
             CPUID_7_0_EBX_SMAP,
+        .features[FEAT_XSAVE] =
+            CPUID_XSAVE_XSAVEOPT,
         .xlevel = 0x8000000A,
         .model_id = "Intel Core Processor (Broadwell)",
     },
@@ -1202,6 +1227,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
             CPUID_EXT3_3DNOWPREFETCH | CPUID_EXT3_MISALIGNSSE |
             CPUID_EXT3_SSE4A | CPUID_EXT3_ABM | CPUID_EXT3_SVM |
             CPUID_EXT3_LAHF_LM,
+        /* no xsaveopt! */
         .xlevel = 0x8000001A,
         .model_id = "AMD Opteron 62xx class CPU",
     },
@@ -1236,6 +1262,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
             CPUID_EXT3_3DNOWPREFETCH | CPUID_EXT3_MISALIGNSSE |
             CPUID_EXT3_SSE4A | CPUID_EXT3_ABM | CPUID_EXT3_SVM |
             CPUID_EXT3_LAHF_LM,
+        /* no xsaveopt! */
         .xlevel = 0x8000001A,
         .model_id = "AMD Opteron 63xx class CPU",
     },
@@ -2377,7 +2404,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             *eax |= kvm_mask & (XSTATE_FP | XSTATE_SSE);
             *ebx = *ecx;
         } else if (count == 1) {
-            *eax = kvm_arch_get_supported_cpuid(s, 0xd, 1, R_EAX);
+            *eax = env->features[FEAT_XSAVE];
         } else if (count < ARRAY_SIZE(ext_save_areas)) {
             const ExtSaveArea *esa = &ext_save_areas[count];
             if ((env->features[esa->feature] & esa->bits) == esa->bits &&

target-i386/cpu.h

@@ -411,6 +411,7 @@ typedef enum FeatureWord {
     FEAT_C000_0001_EDX, /* CPUID[C000_0001].EDX */
     FEAT_KVM,           /* CPUID[4000_0001].EAX (KVM_CPUID_FEATURES) */
     FEAT_SVM,           /* CPUID[8000_000A].EDX */
+    FEAT_XSAVE,         /* CPUID[EAX=0xd,ECX=1].EAX */
     FEATURE_WORDS,
 } FeatureWord;
 
@@ -571,6 +572,11 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
 #define CPUID_7_0_EBX_AVX512ER (1U << 27) /* AVX-512 Exponential and Reciprocal */
 #define CPUID_7_0_EBX_AVX512CD (1U << 28) /* AVX-512 Conflict Detection */
 
+#define CPUID_XSAVE_XSAVEOPT   (1U << 0)
+#define CPUID_XSAVE_XSAVEC     (1U << 1)
+#define CPUID_XSAVE_XGETBV1    (1U << 2)
+#define CPUID_XSAVE_XSAVES     (1U << 3)
+
 /* CPUID[0x80000007].EDX flags: */
 #define CPUID_APM_INVTSC       (1U << 8)