1 /* SPDX-License-Identifier: MIT */ 2 /****************************************************************************** 3 * tpmif.h 4 * 5 * TPM I/O interface for Xen guest OSes. 6 * 7 * Copyright (c) 2005, IBM Corporation 8 * 9 * Author: Stefan Berger, stefanb@us.ibm.com 10 * Grant table support: Mahadevan Gomathisankaran 11 * 12 * This code has been derived from tools/libxc/xen/io/netif.h 13 * 14 * Copyright (c) 2003-2004, Keir Fraser 15 */ 16 17 #ifndef __XEN_PUBLIC_IO_TPMIF_H__ 18 #define __XEN_PUBLIC_IO_TPMIF_H__ 19 20 #include "../grant_table.h" 21 22 struct tpmif_tx_request { 23 unsigned long addr; /* Machine address of packet. */ 24 grant_ref_t ref; /* grant table access reference */ 25 uint16_t unused; 26 uint16_t size; /* Packet size in bytes. */ 27 }; 28 typedef struct tpmif_tx_request tpmif_tx_request_t; 29 30 /* 31 * The TPMIF_TX_RING_SIZE defines the number of pages the 32 * front-end and backend can exchange (= size of array). 33 */ 34 typedef uint32_t TPMIF_RING_IDX; 35 36 #define TPMIF_TX_RING_SIZE 1 37 38 /* This structure must fit in a memory page. */ 39 40 struct tpmif_ring { 41 struct tpmif_tx_request req; 42 }; 43 typedef struct tpmif_ring tpmif_ring_t; 44 45 struct tpmif_tx_interface { 46 struct tpmif_ring ring[TPMIF_TX_RING_SIZE]; 47 }; 48 typedef struct tpmif_tx_interface tpmif_tx_interface_t; 49 50 /****************************************************************************** 51 * TPM I/O interface for Xen guest OSes, v2 52 * 53 * Author: Daniel De Graaf <dgdegra@tycho.nsa.gov> 54 * 55 * This protocol emulates the request/response behavior of a TPM using a Xen 56 * shared memory interface. All interaction with the TPM is at the direction 57 * of the frontend, since a TPM (hardware or virtual) is a passive device - 58 * the backend only processes commands as requested by the frontend. 59 * 60 * The frontend sends a request to the TPM by populating the shared page with 61 * the request packet, changing the state to TPMIF_STATE_SUBMIT, and sending 62 * and event channel notification. When the backend is finished, it will set 63 * the state to TPMIF_STATE_FINISH and send an event channel notification. 64 * 65 * In order to allow long-running commands to be canceled, the frontend can 66 * at any time change the state to TPMIF_STATE_CANCEL and send a notification. 67 * The TPM can either finish the command (changing state to TPMIF_STATE_FINISH) 68 * or can cancel the command and change the state to TPMIF_STATE_IDLE. The TPM 69 * can also change the state to TPMIF_STATE_IDLE instead of TPMIF_STATE_FINISH 70 * if another reason for cancellation is required - for example, a physical 71 * TPM may cancel a command if the interface is seized by another locality. 72 * 73 * The TPM command format is defined by the TCG, and is available at 74 * http://www.trustedcomputinggroup.org/resources/tpm_main_specification 75 */ 76 77 enum tpmif_state { 78 TPMIF_STATE_IDLE, /* no contents / vTPM idle / cancel complete */ 79 TPMIF_STATE_SUBMIT, /* request ready / vTPM working */ 80 TPMIF_STATE_FINISH, /* response ready / vTPM idle */ 81 TPMIF_STATE_CANCEL, /* cancel requested / vTPM working */ 82 }; 83 /* Note: The backend should only change state to IDLE or FINISH, while the 84 * frontend should only change to SUBMIT or CANCEL. Status changes do not need 85 * to use atomic operations. 86 */ 87 88 89 /* The shared page for vTPM request/response packets looks like: 90 * 91 * Offset Contents 92 * ================================================= 93 * 0 struct tpmif_shared_page 94 * 16 [optional] List of grant IDs 95 * 16+4*nr_extra_pages TPM packet data 96 * 97 * If the TPM packet data extends beyond the end of a single page, the grant IDs 98 * defined in extra_pages are used as if they were mapped immediately following 99 * the primary shared page. The grants are allocated by the frontend and mapped 100 * by the backend. Before sending a request spanning multiple pages, the 101 * frontend should verify that the TPM supports such large requests by querying 102 * the TPM_CAP_PROP_INPUT_BUFFER property from the TPM. 103 */ 104 struct tpmif_shared_page { 105 uint32_t length; /* request/response length in bytes */ 106 107 uint8_t state; /* enum tpmif_state */ 108 uint8_t locality; /* for the current request */ 109 uint8_t pad; /* should be zero */ 110 111 uint8_t nr_extra_pages; /* extra pages for long packets; may be zero */ 112 uint32_t extra_pages[0]; /* grant IDs; length is actually nr_extra_pages */ 113 }; 114 typedef struct tpmif_shared_page tpmif_shared_page_t; 115 116 #endif 117 118 /* 119 * Local variables: 120 * mode: C 121 * c-file-style: "BSD" 122 * c-basic-offset: 4 123 * tab-width: 4 124 * indent-tabs-mode: nil 125 * End: 126 */ 127