Kconfig: Add CONFIG_SGX support

Add new CONFIG_SGX for sgx support in the Qemu, and the Kconfig
default enable sgx in the i386 platform.

Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20210719112136.57018-32-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configs/devices/i386-softmmu/default.mak

@@ -22,6 +22,7 @@
 #CONFIG_TPM_CRB=n
 #CONFIG_TPM_TIS_ISA=n
 #CONFIG_VTD=n
+#CONFIG_SGX=n
 
 # Boards:
 #

hw/i386/Kconfig

@@ -6,6 +6,10 @@ config SEV
     select X86_FW_OVMF
     depends on KVM
 
+config SGX
+    bool
+    depends on KVM
+
 config PC
     bool
     imply APPLESMC
@@ -21,6 +25,7 @@ config PC
     imply PVPANIC_ISA
     imply QXL
     imply SEV
+    imply SGX
     imply SGA
     imply TEST_DEVICES
     imply TPM_CRB