1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 ============================================= 3 =============================================
4 AMD-TEE (AMD's Trusted Execution Environment) 4 AMD-TEE (AMD's Trusted Execution Environment)
5 ============================================= 5 =============================================
6 6
7 The AMD-TEE driver handles the communication w 7 The AMD-TEE driver handles the communication with AMD's TEE environment. The
8 TEE environment is provided by AMD Secure Proc 8 TEE environment is provided by AMD Secure Processor.
9 9
10 The AMD Secure Processor (formerly called Plat 10 The AMD Secure Processor (formerly called Platform Security Processor or PSP)
11 is a dedicated processor that features ARM Tru 11 is a dedicated processor that features ARM TrustZone technology, along with a
12 software-based Trusted Execution Environment ( 12 software-based Trusted Execution Environment (TEE) designed to enable
13 third-party Trusted Applications. This feature 13 third-party Trusted Applications. This feature is currently enabled only for
14 APUs. 14 APUs.
15 15
16 The following picture shows a high level overv 16 The following picture shows a high level overview of AMD-TEE::
17 17
18 | 18 |
19 x86 | 19 x86 |
20 | 20 |
21 User space (Kernel space) | 21 User space (Kernel space) | AMD Secure Processor (PSP)
22 ~~~~~~~~~~ ~~~~~~~~~~~~~~ | 22 ~~~~~~~~~~ ~~~~~~~~~~~~~~ | ~~~~~~~~~~~~~~~~~~~~~~~~~~
23 | 23 |
24 +--------+ | 24 +--------+ | +-------------+
25 | Client | | 25 | Client | | | Trusted |
26 +--------+ | 26 +--------+ | | Application |
27 /\ | 27 /\ | +-------------+
28 || | 28 || | /\
29 || | 29 || | ||
30 || | 30 || | \/
31 || | 31 || | +----------+
32 || | 32 || | | TEE |
33 || | 33 || | | Internal |
34 \/ | 34 \/ | | API |
35 +---------+ +-----------+---------+ 35 +---------+ +-----------+---------+ +----------+
36 | TEE | | TEE | AMD-TEE | 36 | TEE | | TEE | AMD-TEE | | AMD-TEE |
37 | Client | | subsystem | driver | 37 | Client | | subsystem | driver | | Trusted |
38 | API | | | | 38 | API | | | | | OS |
39 +---------+-----------+----+------+---------+ 39 +---------+-----------+----+------+---------+---------+----------+
40 | Generic TEE API | | ASP | 40 | Generic TEE API | | ASP | Mailbox |
41 | IOCTL (TEE_IOC_*) | | driver | 41 | IOCTL (TEE_IOC_*) | | driver | Register Protocol |
42 +--------------------------+ +---------+ 42 +--------------------------+ +---------+--------------------+
43 43
44 At the lowest level (in x86), the AMD Secure P 44 At the lowest level (in x86), the AMD Secure Processor (ASP) driver uses the
45 CPU to PSP mailbox register to submit commands 45 CPU to PSP mailbox register to submit commands to the PSP. The format of the
46 command buffer is opaque to the ASP driver. It 46 command buffer is opaque to the ASP driver. It's role is to submit commands to
47 the secure processor and return results to AMD 47 the secure processor and return results to AMD-TEE driver. The interface
48 between AMD-TEE driver and AMD Secure Processo 48 between AMD-TEE driver and AMD Secure Processor driver can be found in [1].
49 49
50 The AMD-TEE driver packages the command buffer 50 The AMD-TEE driver packages the command buffer payload for processing in TEE.
51 The command buffer format for the different TE 51 The command buffer format for the different TEE commands can be found in [2].
52 52
53 The TEE commands supported by AMD-TEE Trusted 53 The TEE commands supported by AMD-TEE Trusted OS are:
54 54
55 * TEE_CMD_ID_LOAD_TA - loads a Truste 55 * TEE_CMD_ID_LOAD_TA - loads a Trusted Application (TA) binary into
56 TEE environmen 56 TEE environment.
57 * TEE_CMD_ID_UNLOAD_TA - unloads TA bin 57 * TEE_CMD_ID_UNLOAD_TA - unloads TA binary from TEE environment.
58 * TEE_CMD_ID_OPEN_SESSION - opens a sessio 58 * TEE_CMD_ID_OPEN_SESSION - opens a session with a loaded TA.
59 * TEE_CMD_ID_CLOSE_SESSION - closes session 59 * TEE_CMD_ID_CLOSE_SESSION - closes session with loaded TA
60 * TEE_CMD_ID_INVOKE_CMD - invokes a comm 60 * TEE_CMD_ID_INVOKE_CMD - invokes a command with loaded TA
61 * TEE_CMD_ID_MAP_SHARED_MEM - maps shared me 61 * TEE_CMD_ID_MAP_SHARED_MEM - maps shared memory
62 * TEE_CMD_ID_UNMAP_SHARED_MEM - unmaps shared 62 * TEE_CMD_ID_UNMAP_SHARED_MEM - unmaps shared memory
63 63
64 AMD-TEE Trusted OS is the firmware running on 64 AMD-TEE Trusted OS is the firmware running on AMD Secure Processor.
65 65
66 The AMD-TEE driver registers itself with TEE s 66 The AMD-TEE driver registers itself with TEE subsystem and implements the
67 following driver function callbacks: 67 following driver function callbacks:
68 68
69 * get_version - returns the driver implementat 69 * get_version - returns the driver implementation id and capability.
70 * open - sets up the driver context data struc 70 * open - sets up the driver context data structure.
71 * release - frees up driver resources. 71 * release - frees up driver resources.
72 * open_session - loads the TA binary and opens 72 * open_session - loads the TA binary and opens session with loaded TA.
73 * close_session - closes session with loaded 73 * close_session - closes session with loaded TA and unloads it.
74 * invoke_func - invokes a command with loaded 74 * invoke_func - invokes a command with loaded TA.
75 75
76 cancel_req driver callback is not supported by 76 cancel_req driver callback is not supported by AMD-TEE.
77 77
78 The GlobalPlatform TEE Client API [3] can be u 78 The GlobalPlatform TEE Client API [3] can be used by the user space (client) to
79 talk to AMD's TEE. AMD's TEE provides a secure 79 talk to AMD's TEE. AMD's TEE provides a secure environment for loading, opening
80 a session, invoking commands and closing sessi 80 a session, invoking commands and closing session with TA.
81 81
82 References 82 References
83 ========== 83 ==========
84 84
85 [1] include/linux/psp-tee.h 85 [1] include/linux/psp-tee.h
86 86
87 [2] drivers/tee/amdtee/amdtee_if.h 87 [2] drivers/tee/amdtee/amdtee_if.h
88 88
89 [3] http://www.globalplatform.org/specificatio 89 [3] http://www.globalplatform.org/specificationsdevice.asp look for
90 "TEE Client API Specification v1.0" and cl 90 "TEE Client API Specification v1.0" and click download.
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