1 files changed, 125 insertions, 0 deletions
diff --git a/src/security/intel/txt/romstage.c b/src/security/intel/txt/romstage.c
new file mode 100644
index 0000000000..7a12debd6d
--- /dev/null
+++ b/src/security/intel/txt/romstage.c
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <arch/mmio.h>
+#include <cf9_reset.h>
+#include <console/console.h>
+#include <cpu/intel/common/common.h>
+#include <cpu/x86/msr.h>
+#include <southbridge/intel/common/pmbase.h>
+#include <timer.h>
+#include <types.h>
+
+#include <security/tpm/tis.h>
+
+#include "txt.h"
+#include "txt_register.h"
+#include "txt_getsec.h"
+
+static bool is_establishment_bit_asserted(void)
+{
+	struct stopwatch timer;
+	uint8_t access;
+
+	/* Spec says no less than 30 milliseconds */
+	stopwatch_init_msecs_expire(&timer, 50);
+
+	while (true) {
+		access = read8((void *)TPM_ACCESS_REG);
+
+		/* Register returns all ones if TPM is missing */
+		if (access == 0xff)
+			return false;
+
+		if (access & TPM_ACCESS_VALID)
+			break;
+
+		/* On timeout, assume that the TPM is not working */
+		if (stopwatch_expired(&timer))
+			return false;
+	}
+
+	/* This bit uses inverted logic: if cleared, establishment is asserted */
+	return !(access & TPM_ACCESS_ESTABLISHMENT);
+}
+
+static bool is_txt_cpu(void)
+{
+	const uint32_t ecx = cpu_get_feature_flags_ecx();
+
+	return (ecx & (CPUID_SMX | CPUID_VMX)) == (CPUID_SMX | CPUID_VMX);
+}
+
+static bool is_txt_chipset(void)
+{
+	uint32_t eax;
+
+	const bool success = getsec_capabilities(&eax);
+
+	return success && eax & 1;
+}
+
+/* Print the bad news */
+static void print_memory_is_locked(void)
+{
+	if (!CONFIG(INTEL_TXT_LOGGING))
+		return;
+
+	printk(BIOS_EMERG, "FATAL: Cannot run SCLEAN. Memory will remain locked.\n");
+	printk(BIOS_EMERG, "\n");
+	printk(BIOS_EMERG, "If you still want to boot, your options are:\n");
+	printk(BIOS_EMERG, "\n");
+	printk(BIOS_EMERG, "   1. Flash a coreboot image with a valid BIOS ACM.\n");
+	printk(BIOS_EMERG, "      Then, try again and hope it works this time.\n");
+	printk(BIOS_EMERG, "\n");
+	printk(BIOS_EMERG, "   2. If possible, remove the TPM from the system.\n");
+	printk(BIOS_EMERG, "      Reinstalling the TPM might lock memory again.\n");
+	printk(BIOS_EMERG, "\n");
+	printk(BIOS_EMERG, "   3. Disconnect all power sources, and RTC battery.\n");
+	printk(BIOS_EMERG, "      This may not work on all TXT-enabled platforms.\n");
+	printk(BIOS_EMERG, "\n");
+}
+
+void intel_txt_romstage_init(void)
+{
+	/* Bail early if the CPU doesn't support TXT */
+	if (!is_txt_cpu())
+		return;
+
+	/* We need to use GETSEC here, so enable it */
+	enable_getsec_or_reset();
+
+	if (!is_txt_chipset())
+		return;
+
+	const uint8_t txt_ests = read8((void *)TXT_ESTS);
+
+	const bool establishment = is_establishment_bit_asserted();
+	const bool is_wake_error = !!(txt_ests & TXT_ESTS_WAKE_ERROR_STS);
+
+	if (CONFIG(INTEL_TXT_LOGGING)) {
+
+		printk(BIOS_INFO, "TEE-TXT: TPM established: %s\n",
+		       establishment ? "true" : "false");
+	}
+
+	if (establishment && is_wake_error) {
+
+		printk(BIOS_ERR, "TEE-TXT: Secrets remain in memory. SCLEAN is required.\n");
+
+		if (txt_ests & TXT_ESTS_TXT_RESET_STS) {
+			printk(BIOS_ERR, "TEE-TXT: TXT_RESET bit set, doing full reset!\n");
+			full_reset();
+		}
+
+		/* FIXME: Clear SLP_TYP# */
+		write_pmbase32(4, read_pmbase32(4) & ~(0x7 << 10));
+
+		intel_txt_run_sclean();
+
+		/* If running the BIOS ACM is impossible, manual intervention is required */
+		print_memory_is_locked();
+
+		/* FIXME: vboot A/B could be used to recover, but has not been tested */
+		die("Could not execute BIOS ACM to unlock the memory.\n");
+	}
+}