@@ -17,3 +17,4 @@ endif
common-obj-$(call land,$(CONFIG_VHOST_USER),$(CONFIG_VIRTIO)) += vhost-user.o
common-obj-$(CONFIG_LINUX) += hostmem-memfd.o
+common-obj-$(CONFIG_LINUX) += hostmem-epc.o
new file mode 100644
@@ -0,0 +1,91 @@
+/*
+ * QEMU host SGX EPC memory backend
+ *
+ * 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.
+ */
+#include <sys/ioctl.h>
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qom/object_interfaces.h"
+#include "qapi/error.h"
+#include "sysemu/hostmem.h"
+
+#define TYPE_MEMORY_BACKEND_EPC "memory-backend-epc"
+
+#define MEMORY_BACKEND_EPC(obj) \
+ OBJECT_CHECK(HostMemoryBackendEpc, (obj), TYPE_MEMORY_BACKEND_EPC)
+
+typedef struct HostMemoryBackendEpc HostMemoryBackendEpc;
+
+struct HostMemoryBackendEpc {
+ HostMemoryBackend parent_obj;
+};
+
+static void
+sgx_epc_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
+{
+ char *name;
+ int fd;
+
+ if (!backend->size) {
+ error_setg(errp, "can't create backend with size 0");
+ return;
+ }
+ backend->force_prealloc = mem_prealloc;
+
+ fd = open("/dev/sgx/virt_epc", O_RDWR);
+ if (fd < 0) {
+ error_setg_errno(errp, errno,
+ "failed to open /dev/sgx/virt_epc to alloc SGX EPC");
+ return;
+ }
+
+ name = object_get_canonical_path(OBJECT(backend));
+ memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
+ name, backend->size,
+ backend->share, fd, errp);
+ g_free(name);
+}
+
+static void sgx_epc_backend_instance_init(Object *obj)
+{
+ HostMemoryBackend *m = MEMORY_BACKEND(obj);
+
+ m->share = true;
+ m->merge = false;
+ m->dump = false;
+}
+
+static void sgx_epc_backend_class_init(ObjectClass *oc, void *data)
+{
+ HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
+
+ bc->alloc = sgx_epc_backend_memory_alloc;
+}
+
+static const TypeInfo sgx_epc_backed_info = {
+ .name = TYPE_MEMORY_BACKEND_EPC,
+ .parent = TYPE_MEMORY_BACKEND,
+ .instance_init = sgx_epc_backend_instance_init,
+ .class_init = sgx_epc_backend_class_init,
+ .instance_size = sizeof(HostMemoryBackendEpc),
+};
+
+static void register_types(void)
+{
+ int fd = open("/dev/sgx/virt_epc", O_RDWR);
+ if (fd >= 0) {
+ close(fd);
+
+ type_register_static(&sgx_epc_backed_info);
+ }
+}
+
+type_init(register_types);
EPC (Enclave Page Cache) is a specialized type of memory used by Intel SGX (Software Guard Extensions). The SDM desribes EPC as: The Enclave Page Cache (EPC) is the secure storage used to store enclave pages when they are a part of an executing enclave. For an EPC page, hardware performs additional access control checks to restrict access to the page. After the current page access checks and translations are performed, the hardware checks that the EPC page is accessible to the program currently executing. Generally an EPC page is only accessed by the owner of the executing enclave or an instruction which is setting up an EPC page. Because of its unique requirements, Linux manages EPC separately from normal memory. Similar to memfd, the device /dev/sgx/virt_epc can be opened to obtain a file descriptor which can in turn be used to mmap() EPC memory. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- backends/Makefile.objs | 1 + backends/hostmem-epc.c | 91 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 92 insertions(+) create mode 100644 backends/hostmem-epc.c