From 8939b0f8e0b57631841f6412a2c568e381392a2a Mon Sep 17 00:00:00 2001
From: Julio Montes <julio.montes@intel.com>
Date: Fri, 14 Jan 2022 13:11:03 -0600
Subject: [PATCH] qemu: add support for SGX

Define and implement memory-backend-epc object

Signed-off-by: Julio Montes <julio.montes@intel.com>
---
 qemu/qemu.go      | 16 ++++++++++++++++
 qemu/qemu_test.go | 13 +++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/qemu/qemu.go b/qemu/qemu.go
index f6db8481d3..c43ff57955 100644
--- a/qemu/qemu.go
+++ b/qemu/qemu.go
@@ -234,6 +234,9 @@ const (
 	// MemoryBackendFile represents a guest memory mapped file.
 	MemoryBackendFile ObjectType = "memory-backend-file"
 
+	// MemoryBackendEPC represents a guest memory backend EPC for SGX.
+	MemoryBackendEPC ObjectType = "memory-backend-epc"
+
 	// TDXGuest represents a TDX object
 	TDXGuest ObjectType = "tdx-guest"
 
@@ -283,6 +286,9 @@ type Object struct {
 
 	// ReadOnly specifies whether `MemPath` is opened read-only or read/write (default)
 	ReadOnly bool
+
+	// Prealloc enables memory preallocation
+	Prealloc bool
 }
 
 // Valid returns true if the Object structure is valid and complete.
@@ -290,6 +296,8 @@ func (object Object) Valid() bool {
 	switch object.Type {
 	case MemoryBackendFile:
 		return object.ID != "" && object.MemPath != "" && object.Size != 0
+	case MemoryBackendEPC:
+		return object.ID != "" && object.Size != 0
 	case TDXGuest:
 		return object.ID != "" && object.File != "" && object.DeviceID != ""
 	case SEVGuest:
@@ -326,6 +334,14 @@ func (object Object) QemuParams(config *Config) []string {
 			objectParams = append(objectParams, "readonly=on")
 			deviceParams = append(deviceParams, "unarmed=on")
 		}
+	case MemoryBackendEPC:
+		objectParams = append(objectParams, string(object.Type))
+		objectParams = append(objectParams, fmt.Sprintf("id=%s", object.ID))
+		objectParams = append(objectParams, fmt.Sprintf("size=%d", object.Size))
+		if object.Prealloc {
+			objectParams = append(objectParams, "prealloc=on")
+		}
+
 	case TDXGuest:
 		objectParams = append(objectParams, string(object.Type))
 		objectParams = append(objectParams, fmt.Sprintf("id=%s", object.ID))
diff --git a/qemu/qemu_test.go b/qemu/qemu_test.go
index e423661544..2e37b0e166 100644
--- a/qemu/qemu_test.go
+++ b/qemu/qemu_test.go
@@ -144,6 +144,19 @@ func TestAppendDeviceNVDIMM(t *testing.T) {
 	testAppend(object, deviceNVDIMMString, t)
 }
 
+var objectEPCString = "-object memory-backend-epc,id=epc0,size=65536,prealloc=on"
+
+func TestAppendEPCObject(t *testing.T) {
+	object := Object{
+		Type:     MemoryBackendEPC,
+		ID:       "epc0",
+		Size:     1 << 16,
+		Prealloc: true,
+	}
+
+	testAppend(object, objectEPCString, t)
+}
+
 func TestAppendDeviceFS(t *testing.T) {
 	fsdev := FSDevice{
 		Driver:        Virtio9P,