[PATCH v2 1/4] powerpc/powernv: Add OPAL API interface to access secure variable

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

The X.509 certificates trusted by the platform and required to secure boot
the OS kernel are wrapped in secure variables, which are controlled by
OPAL.

This patch adds firmware/kernel interface to read and write OPAL secure
variables based on the unique key.

This support can be enabled using CONFIG_OPAL_SECVAR.

Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
---
 arch/powerpc/include/asm/opal-api.h          |   5 +-
 arch/powerpc/include/asm/opal.h              |   6 ++
 arch/powerpc/include/asm/secvar.h            |  55 ++++++++++
 arch/powerpc/kernel/Makefile                 |   2 +-
 arch/powerpc/kernel/secvar-ops.c             |  25 +++++
 arch/powerpc/platforms/powernv/Kconfig       |   6 ++
 arch/powerpc/platforms/powernv/Makefile      |   1 +
 arch/powerpc/platforms/powernv/opal-call.c   |   3 +
 arch/powerpc/platforms/powernv/opal-secvar.c | 102 +++++++++++++++++++
 arch/powerpc/platforms/powernv/opal.c        |   5 +
 10 files changed, 208 insertions(+), 2 deletions(-)
 create mode 100644 arch/powerpc/include/asm/secvar.h
 create mode 100644 arch/powerpc/kernel/secvar-ops.c
 create mode 100644 arch/powerpc/platforms/powernv/opal-secvar.c

diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
index 383242eb0dea..b238b4f26c5b 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -208,7 +208,10 @@
 #define OPAL_HANDLE_HMI2			166
 #define	OPAL_NX_COPROC_INIT			167
 #define OPAL_XIVE_GET_VP_STATE			170
-#define OPAL_LAST				170
+#define OPAL_SECVAR_GET                         173
+#define OPAL_SECVAR_GET_NEXT                    174
+#define OPAL_SECVAR_ENQUEUE_UPDATE              175
+#define OPAL_LAST                               175
 
 #define QUIESCE_HOLD			1 /* Spin all calls at entry */
 #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 57bd029c715e..247adec2375f 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -388,6 +388,12 @@ void opal_powercap_init(void);
 void opal_psr_init(void);
 void opal_sensor_groups_init(void);
 
+extern int opal_secvar_get(uint64_t k_key, uint64_t k_key_len,
+			   uint64_t k_data, uint64_t k_data_size);
+extern int opal_secvar_get_next(uint64_t k_key, uint64_t k_key_len,
+				uint64_t k_key_size);
+extern int opal_secvar_enqueue_update(uint64_t k_key, uint64_t k_key_len,
+				      uint64_t k_data, uint64_t k_data_size);
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_OPAL_H */
diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
new file mode 100644
index 000000000000..645654456265
--- /dev/null
+++ b/arch/powerpc/include/asm/secvar.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PowerPC secure variable operations.
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ */
+#ifndef SECVAR_OPS_H
+#define SECVAR_OPS_H
+
+#include<linux/types.h>
+#include<linux/errno.h>
+
+struct secvar_operations {
+	int (*get_variable)(const char *key, unsigned long key_len, u8 *data,
+			    unsigned long *data_size);
+	int (*get_next_variable)(const char *key, unsigned long *key_len,
+				 unsigned long keysize);
+	int (*set_variable)(const char *key, unsigned long key_len, u8 *data,
+			    unsigned long data_size);
+};
+
+#ifdef CONFIG_PPC_SECURE_BOOT
+
+extern void set_secvar_ops(struct secvar_operations *ops);
+extern struct secvar_operations *get_secvar_ops(void);
+
+#else
+
+static inline void set_secvar_ops(struct secvar_operations *ops)
+{
+}
+
+static inline struct secvar_operations *get_secvar_ops(void)
+{
+	return NULL;
+}
+
+#endif
+
+#ifdef CONFIG_OPAL_SECVAR
+
+extern int secvar_init(void);
+
+#else
+
+static inline int secvar_init(void)
+{
+	return -EINVAL;
+}
+
+#endif
+
+#endif
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 520b1c814197..9041563f1c74 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -157,7 +157,7 @@ endif
 obj-$(CONFIG_EPAPR_PARAVIRT)	+= epapr_paravirt.o epapr_hcalls.o
 obj-$(CONFIG_KVM_GUEST)		+= kvm.o kvm_emul.o
 
-obj-$(CONFIG_PPC_SECURE_BOOT)	+= secboot.o ima_arch.o
+obj-$(CONFIG_PPC_SECURE_BOOT)	+= secboot.o ima_arch.o secvar-ops.o
 
 # Disable GCOV, KCOV & sanitizers in odd or sensitive code
 GCOV_PROFILE_prom_init.o := n
diff --git a/arch/powerpc/kernel/secvar-ops.c b/arch/powerpc/kernel/secvar-ops.c
new file mode 100644
index 000000000000..198222499848
--- /dev/null
+++ b/arch/powerpc/kernel/secvar-ops.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <nayna@linux.ibm.com>
+ *
+ * secvar-ops.c
+ *      - initialize secvar operations for PowerPC Secureboot
+ */
+
+#include<stddef.h>
+#include<asm/secvar.h>
+
+static struct secvar_operations *secvars_ops;
+
+void set_secvar_ops(struct secvar_operations *ops)
+{
+	if (!ops)
+		secvars_ops = NULL;
+	secvars_ops = ops;
+}
+
+struct secvar_operations *get_secvar_ops(void)
+{
+	return secvars_ops;
+}
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index 850eee860cf2..65b060539b5c 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -47,3 +47,9 @@ config PPC_VAS
 	  VAS adapters are found in POWER9 based systems.
 
 	  If unsure, say N.
+
+config OPAL_SECVAR
+	bool "OPAL Secure Variables"
+	depends on PPC_POWERNV
+	help
+	  This enables the kernel to access OPAL secure variables.
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index da2e99efbd04..6651c742e530 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_PERF_EVENTS) += opal-imc.o
 obj-$(CONFIG_PPC_MEMTRACE)	+= memtrace.o
 obj-$(CONFIG_PPC_VAS)	+= vas.o vas-window.o vas-debug.o
 obj-$(CONFIG_OCXL_BASE)	+= ocxl.o
+obj-$(CONFIG_OPAL_SECVAR) += opal-secvar.o
diff --git a/arch/powerpc/platforms/powernv/opal-call.c b/arch/powerpc/platforms/powernv/opal-call.c
index 29ca523c1c79..93106e867924 100644
--- a/arch/powerpc/platforms/powernv/opal-call.c
+++ b/arch/powerpc/platforms/powernv/opal-call.c
@@ -287,3 +287,6 @@ OPAL_CALL(opal_pci_set_pbcq_tunnel_bar,		OPAL_PCI_SET_PBCQ_TUNNEL_BAR);
 OPAL_CALL(opal_sensor_read_u64,			OPAL_SENSOR_READ_U64);
 OPAL_CALL(opal_sensor_group_enable,		OPAL_SENSOR_GROUP_ENABLE);
 OPAL_CALL(opal_nx_coproc_init,			OPAL_NX_COPROC_INIT);
+OPAL_CALL(opal_secvar_get,                     OPAL_SECVAR_GET);
+OPAL_CALL(opal_secvar_get_next,                 OPAL_SECVAR_GET_NEXT);
+OPAL_CALL(opal_secvar_enqueue_update,           OPAL_SECVAR_ENQUEUE_UPDATE);
diff --git a/arch/powerpc/platforms/powernv/opal-secvar.c b/arch/powerpc/platforms/powernv/opal-secvar.c
new file mode 100644
index 000000000000..b0f97cea7675
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-secvar.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PowerNV code for secure variables
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Claudio Carvalho <cclaudio@linux.ibm.com>
+ *
+ * APIs to access secure variables managed by OPAL.
+ *
+ */
+
+#define pr_fmt(fmt) "secvar: "fmt
+
+#include <linux/types.h>
+#include <asm/opal.h>
+#include <asm/secvar.h>
+
+static bool is_opal_secvar_supported(void)
+{
+	static bool opal_secvar_supported;
+	static bool initialized;
+
+	if (initialized)
+		return opal_secvar_supported;
+
+	if (!opal_check_token(OPAL_SECVAR_GET)
+			|| !opal_check_token(OPAL_SECVAR_GET_NEXT)
+			|| !opal_check_token(OPAL_SECVAR_ENQUEUE_UPDATE)) {
+		pr_err("OPAL doesn't support secure variables\n");
+		opal_secvar_supported = false;
+	} else {
+		opal_secvar_supported = true;
+	}
+
+	initialized = true;
+
+	return opal_secvar_supported;
+}
+
+static int opal_get_variable(const char *key, unsigned long ksize,
+			     u8 *data, unsigned long *dsize)
+{
+	int rc;
+
+	if (!is_opal_secvar_supported())
+		return OPAL_UNSUPPORTED;
+
+	if (dsize)
+		*dsize = cpu_to_be64(*dsize);
+
+	rc = opal_secvar_get(__pa(key), ksize,
+			__pa(data), __pa(dsize));
+
+	if (dsize)
+		*dsize = be64_to_cpu(*dsize);
+
+	return rc;
+}
+
+static int opal_get_next_variable(const char *key, unsigned long *keylen,
+				  unsigned long keysize)
+{
+	int rc;
+
+	if (!is_opal_secvar_supported())
+		return OPAL_UNSUPPORTED;
+
+	if (keylen)
+		*keylen = cpu_to_be64(*keylen);
+
+	rc = opal_secvar_get_next(__pa(key), __pa(keylen), keysize);
+
+	if (keylen)
+		*keylen = be64_to_cpu(*keylen);
+
+	return rc;
+}
+
+static int opal_set_variable(const char *key, unsigned long ksize, u8 *data,
+			     unsigned long dsize)
+{
+	int rc;
+
+	if (!is_opal_secvar_supported())
+		return OPAL_UNSUPPORTED;
+
+	rc = opal_secvar_enqueue_update(__pa(key), ksize, __pa(data), dsize);
+
+	return rc;
+}
+
+static struct secvar_operations secvar_ops = {
+	.get_variable = opal_get_variable,
+	.get_next_variable = opal_get_next_variable,
+	.set_variable = opal_set_variable,
+};
+
+int secvar_init(void)
+{
+	set_secvar_ops(&secvar_ops);
+	return 0;
+}
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index aba443be7daa..ffe6f1cf0830 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -32,6 +32,8 @@
 #include <asm/mce.h>
 #include <asm/imc-pmu.h>
 #include <asm/bug.h>
+#include <asm/secvar.h>
+#include <asm/secboot.h>
 
 #include "powernv.h"
 
@@ -988,6 +990,9 @@ static int __init opal_init(void)
 	/* Initialise OPAL Power control interface */
 	opal_power_control_init();
 
+	if (is_powerpc_secvar_supported())
+		secvar_init();
+
 	return 0;
 }
 machine_subsys_initcall(powernv, opal_init);
-- 
2.20.1