CPUID leaf 12_0_EAX is an Intel-defined feature bits leaf enumerating
the CPU's SGX capabilities, e.g. supported SGX instruction sets.
Currently there are four enumerated capabilities:

  - SGX1 instruction set, i.e. "base" SGX
  - SGX2 instruction set for dynamic EPC management
  - ENCLV instruction set for VMM oversubscription of EPC
  - ENCLS-C instruction set for thread safe variants of ENCLS

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 target/i386/cpu.c | 20 ++++++++++++++++++++
 target/i386/cpu.h |  1 +
 2 files changed, 21 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index f529fb0dc8..e954eca4dd 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -775,6 +775,7 @@ static void x86_cpu_vendor_words2str(char *dst, uint32_t vendor1,
 #define TCG_XSAVE_FEATURES (CPUID_XSAVE_XSAVEOPT | CPUID_XSAVE_XGETBV1)
           /* missing:
           CPUID_XSAVE_XSAVEC, CPUID_XSAVE_XSAVES */
+#define TCG_SGX_12_0_EAX_FEATURES 0
 
 typedef enum FeatureWordType {
    CPUID_FEATURE_WORD,
@@ -1224,6 +1225,25 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             },
         },
     },
+    [FEAT_SGX_12_0_EAX] = {
+        .type = CPUID_FEATURE_WORD,
+        .feat_names = {
+            "sgx1", "sgx2", NULL, NULL,
+            NULL, "sgx-enclv", "sgx-encls-c", 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,
+        },
+        .cpuid = {
+            .eax = 0x12,
+            .needs_ecx = true, .ecx = 0,
+            .reg = R_EAX,
+        },
+        .tcg_features = TCG_SGX_12_0_EAX_FEATURES,
+    },
 };
 
 typedef struct X86RegisterInfo32 {
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 62adb2e0d0..6803b1b41d 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -506,6 +506,7 @@ typedef enum FeatureWord {
     FEAT_XSAVE_COMP_HI, /* CPUID[EAX=0xd,ECX=0].EDX */
     FEAT_ARCH_CAPABILITIES,
     FEAT_CORE_CAPABILITY,
+    FEAT_SGX_12_0_EAX,  /* CPUID[EAX=0x12,ECX=0].EAX (SGX) */
     FEATURE_WORDS,
 } FeatureWord;
 
-- 
2.22.0