[PATCH v4 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              |   8 ++
 arch/powerpc/include/asm/powernv.h           |   2 +
 arch/powerpc/include/asm/secvar.h            |  35 +++++
 arch/powerpc/kernel/Makefile                 |   2 +-
 arch/powerpc/kernel/secvar-ops.c             |  19 +++
 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 | 137 +++++++++++++++++++
 arch/powerpc/platforms/powernv/opal.c        |   5 +
 11 files changed, 221 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 378e3997845a..c1f25a760eb1 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -211,7 +211,10 @@
 #define OPAL_MPIPL_UPDATE			173
 #define OPAL_MPIPL_REGISTER_TAG			174
 #define OPAL_MPIPL_QUERY_TAG			175
-#define OPAL_LAST				175
+#define OPAL_SECVAR_GET				176
+#define OPAL_SECVAR_GET_NEXT			177
+#define OPAL_SECVAR_ENQUEUE_UPDATE		178
+#define OPAL_LAST				178
 
 #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 a0cf8fba4d12..03392dc3f5e2 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -298,6 +298,13 @@ int opal_sensor_group_clear(u32 group_hndl, int token);
 int opal_sensor_group_enable(u32 group_hndl, int token, bool enable);
 int opal_nx_coproc_init(uint32_t chip_id, uint32_t ct);
 
+int opal_secvar_get(const char *key, uint64_t key_len, u8 *data,
+		    uint64_t *data_size);
+int opal_secvar_get_next(const char *key, uint64_t *key_len,
+			 uint64_t key_buf_size);
+int opal_secvar_enqueue_update(const char *key, uint64_t key_len, u8 *data,
+			       uint64_t data_size);
+
 s64 opal_mpipl_update(enum opal_mpipl_ops op, u64 src, u64 dest, u64 size);
 s64 opal_mpipl_register_tag(enum opal_mpipl_tags tag, u64 addr);
 s64 opal_mpipl_query_tag(enum opal_mpipl_tags tag, u64 *addr);
@@ -392,6 +399,7 @@ void opal_wake_poller(void);
 void opal_powercap_init(void);
 void opal_psr_init(void);
 void opal_sensor_groups_init(void);
+void opal_secvar_init(void);
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/powerpc/include/asm/powernv.h b/arch/powerpc/include/asm/powernv.h
index e1a858718716..cff980a85dd2 100644
--- a/arch/powerpc/include/asm/powernv.h
+++ b/arch/powerpc/include/asm/powernv.h
@@ -12,10 +12,12 @@ extern void powernv_set_nmmu_ptcr(unsigned long ptcr);
 void pnv_program_cpu_hotplug_lpcr(unsigned int cpu, u64 lpcr_val);
 
 void pnv_tm_init(void);
+
 #else
 static inline void powernv_set_nmmu_ptcr(unsigned long ptcr) { }
 
 static inline void pnv_tm_init(void) { }
+
 #endif
 
 #endif /* _ASM_POWERNV_H */
diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
new file mode 100644
index 000000000000..4cc35b58b986
--- /dev/null
+++ b/arch/powerpc/include/asm/secvar.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain
+ *
+ * PowerPC secure variable operations.
+ */
+#ifndef SECVAR_OPS_H
+#define SECVAR_OPS_H
+
+#include <linux/types.h>
+#include <linux/errno.h>
+
+extern const struct secvar_operations *secvar_ops;
+
+struct secvar_operations {
+	int (*get)(const char *key, uint64_t key_len, u8 *data,
+		   uint64_t *data_size);
+	int (*get_next)(const char *key, uint64_t *key_len,
+			uint64_t keybufsize);
+	int (*set)(const char *key, uint64_t key_len, u8 *data,
+		   uint64_t data_size);
+};
+
+#ifdef CONFIG_PPC_SECURE_BOOT
+
+extern void set_secvar_ops(const struct secvar_operations *ops);
+
+#else
+
+static inline void set_secvar_ops(const struct secvar_operations *ops) { }
+
+#endif
+
+#endif
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index e8eb2955b7d5..3cf26427334f 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -161,7 +161,7 @@ ifneq ($(CONFIG_PPC_POWERNV)$(CONFIG_PPC_SVM),)
 obj-y				+= ucall.o
 endif
 
-obj-$(CONFIG_PPC_SECURE_BOOT)	+= secure_boot.o ima_arch.o
+obj-$(CONFIG_PPC_SECURE_BOOT)	+= secure_boot.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..4331a5b66ec0
--- /dev/null
+++ b/arch/powerpc/kernel/secvar-ops.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain
+ *
+ * This file initializes secvar operations for PowerPC Secureboot
+ */
+
+#include <stddef.h>
+#include <asm/secvar.h>
+
+const struct secvar_operations *secvar_ops;
+
+void set_secvar_ops(const struct secvar_operations *ops)
+{
+	if (!ops)
+		secvar_ops = NULL;
+	secvar_ops = ops;
+}
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index 938803eab0ad..a1c7c8e2e683 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -50,3 +50,9 @@ config PPC_VAS
 config SCOM_DEBUGFS
 	bool "Expose SCOM controllers via debugfs"
 	depends on DEBUG_FS
+
+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 a3ac9646119d..0ae688bde9b7 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -20,3 +20,4 @@ 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_SCOM_DEBUGFS) += opal-xscom.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 a2aa5e433ac8..5cd0f52d258f 100644
--- a/arch/powerpc/platforms/powernv/opal-call.c
+++ b/arch/powerpc/platforms/powernv/opal-call.c
@@ -290,3 +290,6 @@ OPAL_CALL(opal_nx_coproc_init,			OPAL_NX_COPROC_INIT);
 OPAL_CALL(opal_mpipl_update,			OPAL_MPIPL_UPDATE);
 OPAL_CALL(opal_mpipl_register_tag,		OPAL_MPIPL_REGISTER_TAG);
 OPAL_CALL(opal_mpipl_query_tag,			OPAL_MPIPL_QUERY_TAG);
+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..ad5c6b8019dd
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-secvar.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PowerNV code for secure variables
+ *
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Claudio Carvalho
+ *         Nayna Jain
+ *
+ * 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>
+#include <asm/secure_boot.h>
+
+static int opal_status_to_err(int rc)
+{
+	int err;
+
+	switch (rc) {
+	case OPAL_SUCCESS:
+		err = 0;
+		break;
+	case OPAL_UNSUPPORTED:
+		err = -ENXIO;
+		break;
+	case OPAL_PARAMETER:
+		err = -EINVAL;
+		break;
+	case OPAL_RESOURCE:
+		err = -ENOSPC;
+		break;
+	case OPAL_HARDWARE:
+		err = -EIO;
+		break;
+	case OPAL_NO_MEM:
+		err = -ENOMEM;
+		break;
+	case OPAL_EMPTY:
+		err = -ENOENT;
+		break;
+	case OPAL_PARTIAL:
+		err = -EFBIG;
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+static bool is_opal_secvar_supported(void)
+{
+	static bool opal_secvar_supported;
+	static bool initialized;
+
+	if (initialized)
+		return opal_secvar_supported;
+
+	if (!is_powerpc_os_sb_supported()) {
+		opal_secvar_supported = false;
+		goto out;
+	}
+
+	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;
+	}
+
+out:
+	initialized = true;
+
+	return opal_secvar_supported;
+}
+
+static int opal_get_variable(const char *key, uint64_t ksize,
+			     u8 *data, uint64_t *dsize)
+{
+	int rc;
+
+	if (dsize)
+		*dsize = cpu_to_be64(*dsize);
+
+	rc = opal_secvar_get(key, ksize, data, dsize);
+
+	if (dsize)
+		*dsize = be64_to_cpu(*dsize);
+
+	return opal_status_to_err(rc);
+}
+
+static int opal_get_next_variable(const char *key, uint64_t *keylen,
+				  uint64_t keybufsize)
+{
+	int rc;
+
+	if (keylen)
+		*keylen = cpu_to_be64(*keylen);
+
+	rc = opal_secvar_get_next(key, keylen, keybufsize);
+
+	if (keylen)
+		*keylen = be64_to_cpu(*keylen);
+
+	return opal_status_to_err(rc);
+}
+
+static int opal_set_variable(const char *key, uint64_t ksize, u8 *data,
+			     uint64_t dsize)
+{
+	int rc;
+
+	rc = opal_secvar_enqueue_update(key, ksize, data, dsize);
+
+	return opal_status_to_err(rc);
+}
+
+static const struct secvar_operations opal_secvar_ops = {
+	.get = opal_get_variable,
+	.get_next = opal_get_next_variable,
+	.set = opal_set_variable,
+};
+
+void opal_secvar_init(void)
+{
+	if (!is_opal_secvar_supported())
+		set_secvar_ops(NULL);
+
+	set_secvar_ops(&opal_secvar_ops);
+}
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 38e90270280b..8e654d3735c1 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/secure_boot.h>
 
 #include "powernv.h"
 
@@ -1002,6 +1004,9 @@ static int __init opal_init(void)
 	/* Initialise OPAL Power control interface */
 	opal_power_control_init();
 
+	/* Initialize OPAL secure variables */
+	opal_secvar_init();
+
 	return 0;
 }
 machine_subsys_initcall(powernv, opal_init);
-- 
2.20.1