From c6c023200045fc9d61574cb157d368707e18efd5 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 19 Jul 2021 19:21:05 +0800 Subject: [PATCH] hostmem: Add hostmem-epc as a backend for SGX EPC EPC (Enclave Page Cahe) 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_vepc can be opened to obtain a file descriptor which can in turn be used to mmap() EPC memory. Signed-off-by: Sean Christopherson Signed-off-by: Yang Zhong Message-Id: <20210719112136.57018-3-yang.zhong@intel.com> Signed-off-by: Paolo Bonzini --- backends/hostmem-epc.c | 82 +++++++++++++++++++++++++++++++++++ backends/meson.build | 1 + include/hw/i386/hostmem-epc.h | 28 ++++++++++++ 3 files changed, 111 insertions(+) create mode 100644 backends/hostmem-epc.c create mode 100644 include/hw/i386/hostmem-epc.h diff --git a/backends/hostmem-epc.c b/backends/hostmem-epc.c new file mode 100644 index 0000000000..b47f98b6a3 --- /dev/null +++ b/backends/hostmem-epc.c @@ -0,0 +1,82 @@ +/* + * QEMU host SGX EPC memory backend + * + * Copyright (C) 2019 Intel Corporation + * + * Authors: + * Sean Christopherson + * + * 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 + +#include "qemu/osdep.h" +#include "qemu-common.h" +#include "qom/object_interfaces.h" +#include "qapi/error.h" +#include "sysemu/hostmem.h" +#include "hw/i386/hostmem-epc.h" + +static void +sgx_epc_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) +{ + uint32_t ram_flags; + char *name; + int fd; + + if (!backend->size) { + error_setg(errp, "can't create backend with size 0"); + return; + } + + fd = qemu_open_old("/dev/sgx_vepc", O_RDWR); + if (fd < 0) { + error_setg_errno(errp, errno, + "failed to open /dev/sgx_vepc to alloc SGX EPC"); + return; + } + + name = object_get_canonical_path(OBJECT(backend)); + ram_flags = (backend->share ? RAM_SHARED : 0) | RAM_PROTECTED; + memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), + name, backend->size, ram_flags, + fd, 0, 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 = qemu_open_old("/dev/sgx_vepc", O_RDWR); + if (fd >= 0) { + close(fd); + + type_register_static(&sgx_epc_backed_info); + } +} + +type_init(register_types); diff --git a/backends/meson.build b/backends/meson.build index d4221831fc..6e68945528 100644 --- a/backends/meson.build +++ b/backends/meson.build @@ -16,5 +16,6 @@ softmmu_ss.add(when: ['CONFIG_VHOST_USER', 'CONFIG_VIRTIO'], if_true: files('vho softmmu_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('cryptodev-vhost.c')) softmmu_ss.add(when: ['CONFIG_VIRTIO_CRYPTO', 'CONFIG_VHOST_CRYPTO'], if_true: files('cryptodev-vhost-user.c')) softmmu_ss.add(when: 'CONFIG_GIO', if_true: [files('dbus-vmstate.c'), gio]) +softmmu_ss.add(when: 'CONFIG_SGX', if_true: files('hostmem-epc.c')) subdir('tpm') diff --git a/include/hw/i386/hostmem-epc.h b/include/hw/i386/hostmem-epc.h new file mode 100644 index 0000000000..846c726085 --- /dev/null +++ b/include/hw/i386/hostmem-epc.h @@ -0,0 +1,28 @@ +/* + * SGX EPC backend + * + * Copyright (C) 2019 Intel Corporation + * + * Authors: + * Sean Christopherson + * + * 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_HOSTMEM_EPC_H +#define QEMU_HOSTMEM_EPC_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; +}; + +#endif