If qemu cmdline set the prealloc property for sgx epc and VM do the
reset the prealloc property will be different with cmdline settings.
This patch can make sure same prealloc property setting with cmdline.

Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
 backends/hostmem-epc.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/backends/hostmem-epc.c b/backends/hostmem-epc.c
index 3bd1535d82..9836358841 100644
--- a/backends/hostmem-epc.c
+++ b/backends/hostmem-epc.c
@@ -60,6 +60,8 @@ void sgx_memory_backend_reset(HostMemoryBackend *backend, int fd,
                               Error **errp)
 {
     MemoryRegion *mr = &backend->mr;
+    void *ptr;
+    uint64_t sz;
 
     mr->enabled = false;
 
@@ -69,6 +71,14 @@ void sgx_memory_backend_reset(HostMemoryBackend *backend, int fd,
     }
 
     sgx_epc_backend_memory_alloc(backend, errp);
+
+    ptr = memory_region_get_ram_ptr(&backend->mr);
+    sz = memory_region_size(&backend->mr);
+
+    if (backend->prealloc) {
+        os_mem_prealloc(memory_region_get_fd(&backend->mr), ptr, sz,
+                        backend->prealloc_threads, errp);
+    }
 }
 
 static void sgx_epc_backend_instance_init(Object *obj)