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/*
* This file is part of the coreboot project.
*
* Copyright 2017 Google Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <bootstate.h>
#include <console/console.h>
#include <ec/google/chromeec/ec.h>
#include <elog.h>
#include <halt.h>
#include <security/tpm/tss.h>
#include <vb2_api.h>
#include <security/vboot/vboot_common.h>
#include <vendorcode/google/chromeos/chromeos.h>
#define C50_RESET_DELAY_MS 1000
void __weak mainboard_prepare_cr50_reset(void) {}
/**
* Check if the Cr50 TPM state requires a chip reset of the Cr50 device.
*
* Returns 0 if the Cr50 TPM state is good or if the TPM_MODE command is
* unsupported. Returns 1 if the Cr50 was reset.
*/
static int cr50_reset_if_needed(uint16_t timeout_ms)
{
int ret;
int cr50_must_reset = 0;
uint8_t tpm_mode;
ret = tlcl_cr50_get_tpm_mode(&tpm_mode);
if (ret == TPM_E_NO_SUCH_COMMAND) {
printk(BIOS_INFO,
"Cr50 does not support TPM mode command\n");
/* Older Cr50 firmware, assume no Cr50 reset is required */
return 0;
}
if (ret == TPM_E_MUST_REBOOT) {
/*
* Cr50 indicated a reboot is required to restore TPM
* functionality.
*/
cr50_must_reset = 1;
} else if (ret != TPM_SUCCESS) {
/* TPM command failed, continue booting. */
printk(BIOS_ERR,
"ERROR: Attempt to get CR50 TPM mode failed: %x\n", ret);
return 0;
}
/* If the TPM mode is not enabled-tentative, then the TPM mode is locked
* and cannot be changed. Perform a Cr50 reset because vboot may need
* to disable TPM as part of booting an untrusted OS.
*
* This is not an expected state, as the Cr50 always sets the TPM mode
* to TPM_MODE_ENABLED_TENTATIVE during any TPM reset action.
*/
if (tpm_mode != TPM_MODE_ENABLED_TENTATIVE) {
printk(BIOS_NOTICE,
"NOTICE: Unexpected Cr50 TPM mode (%d). "
"A Cr50 reset is required.\n", tpm_mode);
cr50_must_reset = 1;
}
/* If TPM state is okay, no reset needed. */
if (!cr50_must_reset)
return 0;
ret = tlcl_cr50_immediate_reset(timeout_ms);
if (ret != TPM_SUCCESS) {
/* TPM command failed, continue booting. */
printk(BIOS_ERR,
"ERROR: Attempt to reset CR50 failed: %x\n",
ret);
return 0;
}
/* Cr50 is about to be reset, caller needs to prepare */
return 1;
}
static void enable_update(void *unused)
{
int ret;
uint8_t num_restored_headers;
/* Nothing to do on recovery mode. */
if (vboot_recovery_mode_enabled())
return;
ret = tlcl_lib_init();
if (ret != VB2_SUCCESS) {
printk(BIOS_ERR,
"ERROR: tlcl_lib_init() failed for CR50 update: %x\n",
ret);
return;
}
/* Reboot in 1000 ms if necessary. */
ret = tlcl_cr50_enable_update(C50_RESET_DELAY_MS,
&num_restored_headers);
if (ret != TPM_SUCCESS) {
printk(BIOS_ERR,
"ERROR: Attempt to enable CR50 update failed: %x\n",
ret);
return;
}
if (!num_restored_headers) {
/* If no headers were restored there is no reset forthcoming due
* to a Cr50 firmware update. Also check if the Cr50 TPM mode
* requires a reset.
*
* TODO: to eliminate a TPM command during every boot, the
* TURN_UPDATE_ON command could be enhanced/replaced in the Cr50
* firmware to perform the TPM mode/key-ladder check in addition
* to the FW version check.
*/
/*
* If the Cr50 was not reset, continue booting.
*/
if (!cr50_reset_if_needed(C50_RESET_DELAY_MS))
return;
printk(BIOS_INFO, "Waiting for CR50 reset to enable TPM.\n");
elog_add_event(ELOG_TYPE_CR50_NEED_RESET);
} else {
printk(BIOS_INFO,
"Waiting for CR50 reset to pick up update.\n");
elog_add_event(ELOG_TYPE_CR50_UPDATE);
}
/* Give mainboard a chance to take action */
mainboard_prepare_cr50_reset();
/* clear current post code avoid chatty eventlog on subsequent boot*/
post_code(0);
if (IS_ENABLED(CONFIG_POWER_OFF_ON_CR50_UPDATE))
poweroff();
halt();
}
BOOT_STATE_INIT_ENTRY(BS_PAYLOAD_LOAD, BS_ON_ENTRY, enable_update, NULL);
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