[coreboot-gerrit] Change in coreboot[4.11_branch]: mainboard/ocp/monolake: If memory is locked down, clear TPM and reset

[Jonathan Zhang (Code Review)]

Hello Andrey Petrov,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/42711

to review the following change.

Change subject: mainboard/ocp/monolake: If memory is locked down, clear TPM and reset
......................................................................

mainboard/ocp/monolake: If memory is locked down, clear TPM and reset

Under certain conditions TXT can force system to come out of reset with
"locked" memory configuration. This manifests itself in IMC's SMBus
controller not being able to read and SPD. FSP does not seem to detect
this condition and simply fails with "no memory found" error. It turned
out IBB measurements are stored in PCR-0 on TPM and that is what TXT fw
seems to be using to determine if locking needs to be enforced.

This patch detects the locked condition and tries to clear TPM and
reboot the system.

TEST=take an OCP monolake running vendor BIOS that uses TXT.
Ungracefully shut down the system and reflash with coreboot image.
With this patch system manages to get out of bricked state.

Change-Id: I89f87f6ce187c50334c2d3c477d3042528e27fbe
Signed-off-by: Andrey Petrov 
---
M src/mainboard/ocp/monolake/romstage.c
1 file changed, 21 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/11/42711/1

diff --git a/src/mainboard/ocp/monolake/romstage.c b/src/mainboard/ocp/monolake/romstage.c
index ef41b77..d4cd0ad 100644
--- a/src/mainboard/ocp/monolake/romstage.c
+++ b/src/mainboard/ocp/monolake/romstage.c
@@ -17,6 +17,7 @@

#include <stddef.h>
 #include <soc/romstage.h>
+#include <soc/memory.h>
 #include <drivers/intel/fsp1_0/fsp_util.h>
 #include <drivers/vpd/vpd.h>
 #include <cpu/x86/msr.h>
@@ -26,6 +27,9 @@
 #include <soc/pci_devs.h>
 #include <soc/lpc.h>
 #include <soc/gpio.h>
+#include <security/tpm/tspi.h>
+#include <security/tpm/tis.h>
+

/* Define the strings for UPD variables that could be customized */
@@ -207,6 +211,23 @@
    	printk(BIOS_EMERG, "Detected broken platform state. Issuing full reset\n");
    	full_reset();
    }
+
+	/*
+	 * If system have been using TXT and has been ungracefully shutdown and reflashed,
+	 * on next boot TXT fw compares IBB hash against PCR0 in TPM. On mismatch memory
+	 * configuration is locked as a security measure. If we detect this condition we
+	 * can try resetting and clearing TPM, which makes system usable again.
+	 */
+	if (memory_config_is_locked()) {
+		console_init();
+		printk(BIOS_EMERG, "Memory configuration is locked! Clearing TPM.\n");
+		tpm_setup(false);
+		if (tpm_clear_and_reenable() != TPM_SUCCESS) {
+			printk(BIOS_EMERG, "TPM clear success, resetting\n");
+			full_reset();
+		}
+		die("TPM reset failed. Giving up\n");
+	}
 }

/**