vboot: add MINIOS_PRIORITY flag to nvstorage

Flag decides whether MINIOS-A or MINIOS-B is booted.

BUG=b:186682292
TEST=make clean && make runtests
TEST=Deploy and run `crossystem minios_priority` commands
BRANCH=none

Signed-off-by: Joel Kitching <kitching@google.com>
Change-Id: I11460bf1522cde8e98e680b0f00a417e2b4ef9a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2998513
Tested-by: Joel Kitching <kitching@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

5 files changed, 26 insertions, 6 deletions

diff --git a/firmware/2lib/2nvstorage.c b/firmware/2lib/2nvstorage.c
index 1cd5ba25..0f28404b 100644
--- a/firmware/2lib/2nvstorage.c
+++ b/firmware/2lib/2nvstorage.c
@@ -209,6 +209,9 @@ uint32_t vb2_nv_get(struct vb2_context *ctx, enum vb2_nv_param param)
 		return GETBIT(VB2_NV_OFFS_MISC,
 			      VB2_NV_MISC_POST_EC_SYNC_DELAY);
 
+	case VB2_NV_MINIOS_PRIORITY:
+		return GETBIT(VB2_NV_OFFS_MISC, VB2_NV_MISC_MINIOS_PRIORITY);
+
 	case VB2_NV_DEPRECATED_DEV_BOOT_FASTBOOT_FULL_CAP:
 	case VB2_NV_DEPRECATED_FASTBOOT_UNLOCK_IN_FW:
 	case VB2_NV_DEPRECATED_ENABLE_ALT_OS_REQUEST:
@@ -416,6 +419,10 @@ void vb2_nv_set(struct vb2_context *ctx,
 		SETBIT(VB2_NV_OFFS_MISC, VB2_NV_MISC_POST_EC_SYNC_DELAY);
 		break;
 
+	case VB2_NV_MINIOS_PRIORITY:
+		SETBIT(VB2_NV_OFFS_MISC, VB2_NV_MISC_MINIOS_PRIORITY);
+		break;
+
 	case VB2_NV_DEPRECATED_DEV_BOOT_FASTBOOT_FULL_CAP:
 	case VB2_NV_DEPRECATED_FASTBOOT_UNLOCK_IN_FW:
 	case VB2_NV_DEPRECATED_ENABLE_ALT_OS_REQUEST:
diff --git a/firmware/2lib/include/2nvstorage.h b/firmware/2lib/include/2nvstorage.h
index 2f40b233..fe758230 100644
--- a/firmware/2lib/include/2nvstorage.h
+++ b/firmware/2lib/include/2nvstorage.h
@@ -125,6 +125,8 @@ enum vb2_nv_param {
 	VB2_NV_POST_EC_SYNC_DELAY,
 	/* Request booting of diagnostic rom.  0=no, 1=yes. */
 	VB2_NV_DIAG_REQUEST,
+	/* Priority of miniOS partition to load: 0=MINIOS-A, 1=MINIOS-B. */
+	VB2_NV_MINIOS_PRIORITY,
 };
 
 /* Firmware result codes for VB2_NV_FW_RESULT and VB2_NV_FW_PREV_RESULT */
diff --git a/firmware/2lib/include/2nvstorage_fields.h b/firmware/2lib/include/2nvstorage_fields.h
index 9575e87e..449b8fd3 100644
--- a/firmware/2lib/include/2nvstorage_fields.h
+++ b/firmware/2lib/include/2nvstorage_fields.h
@@ -79,7 +79,7 @@ enum vb2_nv_offset {
 #define VB2_NV_BOOT_DISABLE_DEV                0x40
 #define VB2_NV_BOOT_DEBUG_RESET                0x80
 
-/* Fields in VB2_NV_OFFS_BOOT2 (unused = 0x00) */
+/* Fields in VB2_NV_OFFS_BOOT2 */
 #define VB2_NV_BOOT2_RESULT_MASK               0x03
 #define VB2_NV_BOOT2_TRIED                     0x04
 #define VB2_NV_BOOT2_TRY_NEXT                  0x08
@@ -102,11 +102,12 @@ enum vb2_nv_offset {
 #define VB2_NV_TPM_CLEAR_OWNER_DONE            0x02
 #define VB2_NV_TPM_REBOOTED                    0x04
 
-/* Fields in VB2_NV_OFFS_MISC (unused = 0x80) */
+/* Fields in VB2_NV_OFFS_MISC (unused = 0xa0) */
 #define VB2_NV_MISC_DEPRECATED_UNLOCK_FASTBOOT            0x01
 #define VB2_NV_MISC_BOOT_ON_AC_DETECT          0x02
 #define VB2_NV_MISC_TRY_RO_SYNC		       0x04
 #define VB2_NV_MISC_BATTERY_CUTOFF             0x08
+#define VB2_NV_MISC_MINIOS_PRIORITY            0x10
 #define VB2_NV_MISC_POST_EC_SYNC_DELAY         0x40
 
 #endif  /* VBOOT_REFERENCE_2NVSTORAGE_FIELDS_H_ */
diff --git a/host/lib/crossystem.c b/host/lib/crossystem.c
index 9d23091f..a2c2104a 100644
--- a/host/lib/crossystem.c
+++ b/host/lib/crossystem.c
@@ -532,6 +532,8 @@ const char *VbGetSystemPropertyString(const char *name, char *dest,
 			return default_boot[v];
 		else
 			return "unknown";
+	} else if (!strcasecmp(name, "minios_priority")) {
+		return vb2_get_nv_storage(VB2_NV_MINIOS_PRIORITY) ? "B" : "A";
 	}
 
 	return NULL;
@@ -671,7 +673,13 @@ int VbSetSystemPropertyString(const char* name, const char* value)
 			return vb2_set_nv_storage(VB2_NV_TRY_NEXT, 1);
 		else
 			return -1;
-
+	} else if (!strcasecmp(name, "minios_priority")) {
+		if (!strcasecmp(value, "A"))
+			return vb2_set_nv_storage(VB2_NV_MINIOS_PRIORITY, 0);
+		else if (!strcasecmp(value, "B"))
+			return vb2_set_nv_storage(VB2_NV_MINIOS_PRIORITY, 1);
+		else
+			return -1;
 	} else if (!strcasecmp(name, "fw_result")) {
 		int i;
 
diff --git a/utility/crossystem.c b/utility/crossystem.c
index e5774ac2..7781e94e 100644
--- a/utility/crossystem.c
+++ b/utility/crossystem.c
@@ -53,11 +53,11 @@ const Param sys_param_list[] = {
   {"post_ec_sync_delay", CAN_WRITE,
    "Short delay after EC software sync (persistent, writable, eve only)"},
   {"fw_prev_result", IS_STRING, "Firmware result of previous boot"},
-  {"fw_prev_tried", IS_STRING, "Firmware tried on previous boot"},
+  {"fw_prev_tried", IS_STRING, "Firmware tried on previous boot (A or B)"},
   {"fw_result", IS_STRING|CAN_WRITE, "Firmware result this boot"},
-  {"fw_tried", IS_STRING, "Firmware tried this boot"},
+  {"fw_tried", IS_STRING, "Firmware tried this boot (A or B)"},
   {"fw_try_count", CAN_WRITE, "Number of times to try fw_try_next"},
-  {"fw_try_next", IS_STRING|CAN_WRITE, "Firmware to try next"},
+  {"fw_try_next", IS_STRING|CAN_WRITE, "Firmware to try next (A or B)"},
   {"fw_vboot2", 0, "1 if firmware was selected by vboot2 or 0 otherwise"},
   {"fwb_tries", CAN_WRITE, "Try firmware B count"},
   {"fwid", IS_STRING, "Active firmware ID"},
@@ -72,6 +72,8 @@ const Param sys_param_list[] = {
   {"loc_idx", CAN_WRITE, "Localization index for firmware screens"},
   {"mainfw_act", IS_STRING, "Active main firmware"},
   {"mainfw_type", IS_STRING, "Active main firmware type"},
+  {"minios_priority", IS_STRING|CAN_WRITE,
+   "miniOS image to try first (A or B)"},
   {"nvram_cleared", CAN_WRITE, "Have NV settings been lost?  Write 0 to clear"},
   {"display_request", CAN_WRITE, "Should we initialize the display at boot?"},
   {"phase_enforcement", 0,