haswell: Add Intel TXT support in romstage

Provide necessary romstage hooks to allow unblocking the memory with
SCLEAN. Note that this is slow, and took four minutes with 4 GiB of RAM.

Tested on Asrock B85M Pro4 with tboot. When Linux has tboot support
compiled in, booting as well as S3 suspend and resume are functional.
However, SINIT will TXT reset when the iGPU is enabled, and using a dGPU
will result in DMAR-related problems as soon as the IOMMU is enabled.

However, SCLEAN seems to hang sometimes. This may be because the AP
initialization that reference code does before SCLEAN is missing, but
the ACM is still able to unblock the memory. Considering that SCLEAN is
critical to recover an otherwise-bricked platform but is hardly ever
necessary, prefer having a partially-working solution over none at all.

Change-Id: I60beb7d79a30f460bbd5d94e4cba0244318c124e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46608
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

5 files changed, 182 insertions, 0 deletions

diff --git a/src/security/intel/txt/Makefile.inc b/src/security/intel/txt/Makefile.inc
index 762256f6e3..eab47b95f9 100644
--- a/src/security/intel/txt/Makefile.inc
+++ b/src/security/intel/txt/Makefile.inc
@@ -1,6 +1,8 @@
 ifeq ($(CONFIG_INTEL_TXT),y)
 
+romstage-y += romstage.c
 romstage-y += getsec_sclean.S
+romstage-y += getsec.c
 
 romstage-y += common.c
 romstage-$(CONFIG_INTEL_TXT_LOGGING) += logging.c
diff --git a/src/security/intel/txt/common.c b/src/security/intel/txt/common.c
index 88e2b5dddb..4dd4ad3ddf 100644
--- a/src/security/intel/txt/common.c
+++ b/src/security/intel/txt/common.c
@@ -290,6 +290,48 @@ static void *intel_txt_prepare_bios_acm(struct region_device *acm, size_t *acm_l
 	return acm_data;
 }
 
+#define MCU_BASE_ADDR	(TXT_BASE + 0x278)
+#define BIOACM_ADDR	(TXT_BASE + 0x27c)
+#define APINIT_ADDR	(TXT_BASE + 0x290)
+#define SEMAPHORE	(TXT_BASE + 0x294)
+
+/* Returns on failure, resets the computer on success */
+void intel_txt_run_sclean(void)
+{
+	struct region_device acm;
+	size_t acm_len;
+
+	void *acm_data = intel_txt_prepare_bios_acm(&acm, &acm_len);
+
+	if (!acm_data)
+		return;
+
+	/* FIXME: Do we need to program these two? */
+	//write32((void *)MCU_BASE_ADDR, 0xffe1a990);
+	//write32((void *)APINIT_ADDR, 0xfffffff0);
+
+	write32((void *)BIOACM_ADDR, (uintptr_t)acm_data);
+	write32((void *)SEMAPHORE, 0);
+
+	/*
+	 * The time SCLEAN will take depends on the installed RAM size.
+	 * On Haswell with 8 GiB of DDR3, it takes five or ten minutes. (rough estimate)
+	 */
+	printk(BIOS_ALERT, "TEE-TXT: Invoking SCLEAN. This can take several minutes.\n");
+
+	/*
+	 * Invoke the BIOS ACM. If successful, the system will reset with memory unlocked.
+	 */
+	getsec_sclean((uintptr_t)acm_data, acm_len);
+
+	/*
+	 * However, if this function returns, the BIOS ACM could not be invoked. This is bad.
+	 */
+	printk(BIOS_CRIT, "TEE-TXT: getsec_sclean could not launch the BIOS ACM.\n");
+
+	rdev_munmap(&acm, acm_data);
+}
+
 /*
  * Test all bits for TXT execution.
  *
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");
+	}
+}
diff --git a/src/security/intel/txt/txt.h b/src/security/intel/txt/txt.h
index fc5c49e67e..976cc7458e 100644
--- a/src/security/intel/txt/txt.h
+++ b/src/security/intel/txt/txt.h
@@ -17,10 +17,13 @@
 #define ACM_E_UUID_NOT_MATCH                0x09
 #define ACM_E_PLATFORM_IS_NOT_PROD          0x10
 
+void intel_txt_romstage_init(void);
+
 void intel_txt_log_bios_acm_error(void);
 int intel_txt_log_acm_error(const uint32_t acm_error);
 void intel_txt_log_spad(void);
 bool intel_txt_memory_has_secrets(void);
+void intel_txt_run_sclean(void);
 int intel_txt_run_bios_acm(const u8 input_params);
 bool intel_txt_prepare_txt_env(void);
 
diff --git a/src/security/intel/txt/txt_register.h b/src/security/intel/txt/txt_register.h
index c19ec13799..bb735b6cfd 100644
--- a/src/security/intel/txt/txt_register.h
+++ b/src/security/intel/txt/txt_register.h
@@ -99,6 +99,16 @@
 #define  TXT_E2STS_SECRET_STS (1ull << 1)
 
 /*
+ * TCG PC Client Platform TPM Profile (PTP) Specification
+ *
+ * Note: Only locality 0 registers are publicly accessible.
+ */
+
+#define TPM_BASE	0xfed40000UL
+
+#define TPM_ACCESS_REG	(TPM_BASE + 0x00)
+
+/*
  * TXT Memory regions
  * Chapter 5.3
  * Intel Trusted Execution Technology Lab Handout