diff --git a/target/i386/sev.c b/target/i386/sev.c
index 33e606eea0..b2aa0d6f99 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -69,6 +69,8 @@ struct SevCommonState {
 struct SevCommonStateClass {
     X86ConfidentialGuestClass parent_class;
 
+    /* public */
+    int (*launch_start)(SevCommonState *sev_common);
 };
 
 /**
@@ -632,16 +634,16 @@ sev_read_file_base64(const char *filename, guchar **data, gsize *len)
 }
 
 static int
-sev_launch_start(SevGuestState *sev_guest)
+sev_launch_start(SevCommonState *sev_common)
 {
     gsize sz;
     int ret = 1;
     int fw_error, rc;
+    SevGuestState *sev_guest = SEV_GUEST(sev_common);
     struct kvm_sev_launch_start start = {
         .handle = sev_guest->handle, .policy = sev_guest->policy
     };
     guchar *session = NULL, *dh_cert = NULL;
-    SevCommonState *sev_common = SEV_COMMON(sev_guest);
 
     if (sev_guest->session_file) {
         if (sev_read_file_base64(sev_guest->session_file, &session, &sz) < 0) {
@@ -862,6 +864,7 @@ static int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
     uint32_t ebx;
     uint32_t host_cbitpos;
     struct sev_user_data_status status = {};
+    SevCommonStateClass *klass = SEV_COMMON_GET_CLASS(cgs);
 
     ret = ram_block_discard_disable(true);
     if (ret) {
@@ -952,7 +955,7 @@ static int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
         goto err;
     }
 
-    sev_launch_start(SEV_GUEST(sev_common));
+    ret = klass->launch_start(sev_common);
     if (ret) {
         error_setg(errp, "%s: failed to create encryption context", __func__);
         goto err;
@@ -1451,6 +1454,10 @@ static void sev_guest_set_legacy_vm_type(Object *obj, bool value, Error **errp)
 static void
 sev_guest_class_init(ObjectClass *oc, void *data)
 {
+    SevCommonStateClass *klass = SEV_COMMON_CLASS(oc);
+
+    klass->launch_start = sev_launch_start;
+
     object_class_property_add_str(oc, "dh-cert-file",
                                   sev_guest_get_dh_cert_file,
                                   sev_guest_set_dh_cert_file);