[PATCH v3] powerpc/pseries: detect secure and trusted boot state of the system.

[Nayna Jain <nayna@linux.ibm.com>]

The device-tree property to check secure and trusted boot state is
different for guests(pseries) compared to baremetal(powernv).

This patch updates the existing is_ppc_secureboot_enabled() and
is_ppc_trustedboot_enabled() functions to add support for pseries.

The secureboot and trustedboot state are exposed via device-tree property:
/proc/device-tree/ibm,secure-boot and /proc/device-tree/ibm,trusted-boot

The values of ibm,secure-boot under pseries are interpreted as:

0 - Disabled
1 - Enabled in Log-only mode. This patch interprets this value as
disabled, since audit mode is currently not supported for Linux.
2 - Enabled and enforced.
3-9 - Enabled and enforcing; requirements are at the discretion of the
operating system.

The values of ibm,trusted-boot under pseries are interpreted as:
0 - Disabled
1 - Enabled

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
---
v3:
* fixed double check. Thanks Daniel for noticing it.
* updated patch description.

v2:
* included Michael Ellerman's feedback.
* added Daniel Axtens's Reviewed-by.

 arch/powerpc/kernel/secure_boot.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/secure_boot.c b/arch/powerpc/kernel/secure_boot.c
index 4b982324d368..118bcb5f79c4 100644
--- a/arch/powerpc/kernel/secure_boot.c
+++ b/arch/powerpc/kernel/secure_boot.c
@@ -6,6 +6,7 @@
 #include <linux/types.h>
 #include <linux/of.h>
 #include <asm/secure_boot.h>
+#include <asm/machdep.h>
 
 static struct device_node *get_ppc_fw_sb_node(void)
 {
@@ -23,12 +24,19 @@ bool is_ppc_secureboot_enabled(void)
 {
 	struct device_node *node;
 	bool enabled = false;
+	u32 secureboot;
 
 	node = get_ppc_fw_sb_node();
 	enabled = of_property_read_bool(node, "os-secureboot-enforcing");
-
 	of_node_put(node);
 
+	if (enabled)
+		goto out;
+
+	if (!of_property_read_u32(of_root, "ibm,secure-boot", &secureboot))
+		enabled = (secureboot > 1);
+
+out:
 	pr_info("Secure boot mode %s\n", enabled ? "enabled" : "disabled");
 
 	return enabled;
@@ -38,12 +46,19 @@ bool is_ppc_trustedboot_enabled(void)
 {
 	struct device_node *node;
 	bool enabled = false;
+	u32 trustedboot;
 
 	node = get_ppc_fw_sb_node();
 	enabled = of_property_read_bool(node, "trusted-enabled");
-
 	of_node_put(node);
 
+	if (enabled)
+		goto out;
+
+	if (!of_property_read_u32(of_root, "ibm,trusted-boot", &trustedboot))
+		enabled = (trustedboot > 0);
+
+out:
 	pr_info("Trusted boot mode %s\n", enabled ? "enabled" : "disabled");
 
 	return enabled;
-- 
2.26.2