i386: Add 'sgx-epc' device to expose EPC sections to guest

SGX EPC is enumerated through CPUID, i.e. EPC "devices" need to be
realized prior to realizing the vCPUs themselves, which occurs long
before generic devices are parsed and realized.  Because of this,
do not allow 'sgx-epc' devices to be instantiated after vCPUS have
been created.

The 'sgx-epc' device is essentially a placholder at this time, it will
be fully implemented in a future patch along with a dedicated command
to create 'sgx-epc' devices.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20210719112136.57018-5-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/hw/i386/sgx-epc.h

@@ -0,0 +1,44 @@
+/*
+ * SGX EPC device
+ *
+ * Copyright (C) 2019 Intel Corporation
+ *
+ * Authors:
+ *   Sean Christopherson <sean.j.christopherson@intel.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#ifndef QEMU_SGX_EPC_H
+#define QEMU_SGX_EPC_H
+
+#include "hw/i386/hostmem-epc.h"
+
+#define TYPE_SGX_EPC "sgx-epc"
+#define SGX_EPC(obj) \
+    OBJECT_CHECK(SGXEPCDevice, (obj), TYPE_SGX_EPC)
+#define SGX_EPC_CLASS(oc) \
+    OBJECT_CLASS_CHECK(SGXEPCDeviceClass, (oc), TYPE_SGX_EPC)
+#define SGX_EPC_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(SGXEPCDeviceClass, (obj), TYPE_SGX_EPC)
+
+#define SGX_EPC_ADDR_PROP "addr"
+#define SGX_EPC_SIZE_PROP "size"
+#define SGX_EPC_MEMDEV_PROP "memdev"
+
+/**
+ * SGXEPCDevice:
+ * @addr: starting guest physical address, where @SGXEPCDevice is mapped.
+ *         Default value: 0, means that address is auto-allocated.
+ * @hostmem: host memory backend providing memory for @SGXEPCDevice
+ */
+typedef struct SGXEPCDevice {
+    /* private */
+    DeviceState parent_obj;
+
+    /* public */
+    uint64_t addr;
+    HostMemoryBackendEpc *hostmem;
+} SGXEPCDevice;
+
+#endif