[PATCH v2 3/3] powerpc/pseries: Override lib/arch_vars.c with PowerPC architecture specific version

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

From: Greg Joyce <gjoyce@linux.vnet.ibm.com>

Self Encrypting Drives(SED) make use of POWER LPAR Platform KeyStore for
storing its variables. Thus the block subsystem needs to access
PowerPC specific functions to read/write objects in PLPKS.

Override the default implementations in lib/arch_vars.c file with
PowerPC specific versions.

Signed-off-by: Greg Joyce <gjoyce@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/pseries/Makefile       |   1 +
 .../platforms/pseries/plpks_arch_ops.c        | 166 ++++++++++++++++++
 2 files changed, 167 insertions(+)
 create mode 100644 arch/powerpc/platforms/pseries/plpks_arch_ops.c

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 14e143b946a3..3a545422eae5 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_PPC_SPLPAR)	+= vphn.o
 obj-$(CONFIG_PPC_SVM)		+= svm.o
 obj-$(CONFIG_FA_DUMP)		+= rtas-fadump.o
 obj-$(CONFIG_PSERIES_PLPKS) += plpks.o
+obj-$(CONFIG_PSERIES_PLPKS) += plpks_arch_ops.o
 
 obj-$(CONFIG_SUSPEND)		+= suspend.o
 obj-$(CONFIG_PPC_VAS)		+= vas.o vas-sysfs.o
diff --git a/arch/powerpc/platforms/pseries/plpks_arch_ops.c b/arch/powerpc/platforms/pseries/plpks_arch_ops.c
new file mode 100644
index 000000000000..48fa19f0c9c5
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/plpks_arch_ops.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * POWER Platform arch specific code for SED
+ * Copyright (C) 2022 IBM Corporation
+ *
+ * Define operations for generic kernel subsystems to read/write keys from
+ * POWER LPAR Platform KeyStore(PLPKS).
+ *
+ * List of subsystems/usecase using PLPKS:
+ * - Self Encrypting Drives(SED)
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/ioctl.h>
+#include <uapi/linux/sed-opal.h>
+#include <linux/sed-opal.h>
+#include <linux/arch_vars.h>
+#include "plpks.h"
+
+/*
+ * variable structure that contains all SED data
+ */
+struct plpks_sed_object_data {
+	u_char version;
+	u_char pad1[7];
+	u_long authority;
+	u_long range;
+	u_int  key_len;
+	u_char key[32];
+};
+
+/*
+ * ext_type values
+ *	00        no extension exists
+ *	01-1F     common
+ *	20-3F     AIX
+ *	40-5F     Linux
+ *	60-7F     IBMi
+ */
+
+/*
+ * This extension is optional for version 1 sed_object_data
+ */
+struct sed_object_extension {
+	u8 ext_type;
+	u8 rsvd[3];
+	u8 ext_data[64];
+};
+
+#define PKS_SED_OBJECT_DATA_V1          1
+#define PKS_SED_MANGLED_LABEL           "/default/pri"
+#define PLPKS_SED_COMPONENT             "sed-opal"
+#define PLPKS_SED_POLICY                WORLDREADABLE
+#define PLPKS_SED_OS_COMMON             4
+
+#ifndef CONFIG_BLK_SED_OPAL
+#define	OPAL_AUTH_KEY                   ""
+#endif
+
+/*
+ * Read the variable data from PKS given the label
+ */
+int arch_read_variable(enum arch_variable_type type, char *varname,
+		       void *varbuf, u_int *varlen)
+{
+	struct plpks_var var;
+	struct plpks_sed_object_data *data;
+	u_int offset = 0;
+	char *buf = (char *)varbuf;
+	int ret;
+
+	var.name = varname;
+	var.namelen = strlen(varname);
+	var.policy = PLPKS_SED_POLICY;
+	var.os = PLPKS_SED_OS_COMMON;
+	var.data = NULL;
+	var.datalen = 0;
+
+	switch (type) {
+	case ARCH_VAR_OPAL_KEY:
+		var.component = PLPKS_SED_COMPONENT;
+		if (strcmp(OPAL_AUTH_KEY, varname) == 0) {
+			var.name = PKS_SED_MANGLED_LABEL;
+			var.namelen = strlen(varname);
+		}
+		offset = offsetof(struct plpks_sed_object_data, key);
+		break;
+	case ARCH_VAR_OTHER:
+		var.component = "";
+		break;
+	}
+
+	ret = plpks_read_os_var(&var);
+	if (ret != 0)
+		return ret;
+
+	if (offset > var.datalen)
+		offset = 0;
+
+	switch (type) {
+	case ARCH_VAR_OPAL_KEY:
+		data = (struct plpks_sed_object_data *)var.data;
+		*varlen = data->key_len;
+		break;
+	case ARCH_VAR_OTHER:
+		*varlen = var.datalen;
+		break;
+	}
+
+	if (var.data) {
+		memcpy(varbuf, var.data + offset, var.datalen - offset);
+		buf[*varlen] = '\0';
+		kfree(var.data);
+	}
+
+	return 0;
+}
+
+/*
+ * Write the variable data to PKS given the label
+ */
+int arch_write_variable(enum arch_variable_type type, char *varname,
+			void *varbuf, u_int varlen)
+{
+	struct plpks_var var;
+	struct plpks_sed_object_data data;
+	struct plpks_var_name vname;
+
+	var.name = varname;
+	var.namelen = strlen(varname);
+	var.policy = PLPKS_SED_POLICY;
+	var.os = PLPKS_SED_OS_COMMON;
+	var.datalen = varlen;
+	var.data = varbuf;
+
+	switch (type) {
+	case ARCH_VAR_OPAL_KEY:
+		var.component = PLPKS_SED_COMPONENT;
+		if (strcmp(OPAL_AUTH_KEY, varname) == 0) {
+			var.name = PKS_SED_MANGLED_LABEL;
+			var.namelen = strlen(varname);
+		}
+		var.datalen = sizeof(struct plpks_sed_object_data);
+		var.data = (u8 *)&data;
+
+		/* initialize SED object */
+		data.version = PKS_SED_OBJECT_DATA_V1;
+		data.authority = 0;
+		data.range = 0;
+		data.key_len = varlen;
+		memcpy(data.key, varbuf, varlen);
+		break;
+	case ARCH_VAR_OTHER:
+		var.component = "";
+		break;
+	}
+
+	/* variable update requires delete first */
+	vname.namelen = var.namelen;
+	vname.name = var.name;
+	(void)plpks_remove_var(PLPKS_SED_COMPONENT, PLPKS_SED_OS_COMMON, vname);
+
+	return plpks_write_var(var);
+}
-- 
2.27.0