crypto: ccp - Add support for fetching a nonce for dynamic boost control

Dynamic Boost Control is a feature offered on AMD client platforms that
allows software to request and set power or frequency limits.

Only software that has authenticated with the PSP can retrieve or set
these limits.

Create a character device and ioctl for fetching the nonce. This ioctl
supports optionally passing authentication information which will influence
how many calls the nonce is valid for.

Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/ccp/Makefile

@@ -11,7 +11,8 @@ ccp-$(CONFIG_PCI) += sp-pci.o
 ccp-$(CONFIG_CRYPTO_DEV_SP_PSP) += psp-dev.o \
                                    sev-dev.o \
                                    tee-dev.o \
-                                   platform-access.o
+                                   platform-access.o \
+                                   dbc.o
 
 obj-$(CONFIG_CRYPTO_DEV_CCP_CRYPTO) += ccp-crypto.o
 ccp-crypto-objs := ccp-crypto-main.o \

drivers/crypto/ccp/dbc.c

@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Secure Processor Dynamic Boost Control interface
+ *
+ * Copyright (C) 2023 Advanced Micro Devices, Inc.
+ *
+ * Author: Mario Limonciello <mario.limonciello@amd.com>
+ */
+
+#include "dbc.h"
+
+struct error_map {
+	u32 psp;
+	int ret;
+};
+
+#define DBC_ERROR_ACCESS_DENIED		0x0001
+#define DBC_ERROR_EXCESS_DATA		0x0004
+#define DBC_ERROR_BAD_PARAMETERS	0x0006
+#define DBC_ERROR_BAD_STATE		0x0007
+#define DBC_ERROR_NOT_IMPLEMENTED	0x0009
+#define DBC_ERROR_BUSY			0x000D
+#define DBC_ERROR_MESSAGE_FAILURE	0x0307
+#define DBC_ERROR_OVERFLOW		0x300F
+#define DBC_ERROR_SIGNATURE_INVALID	0x3072
+
+static struct error_map error_codes[] = {
+	{DBC_ERROR_ACCESS_DENIED,	-EACCES},
+	{DBC_ERROR_EXCESS_DATA,		-E2BIG},
+	{DBC_ERROR_BAD_PARAMETERS,	-EINVAL},
+	{DBC_ERROR_BAD_STATE,		-EAGAIN},
+	{DBC_ERROR_MESSAGE_FAILURE,	-ENOENT},
+	{DBC_ERROR_NOT_IMPLEMENTED,	-ENOENT},
+	{DBC_ERROR_BUSY,		-EBUSY},
+	{DBC_ERROR_OVERFLOW,		-ENFILE},
+	{DBC_ERROR_SIGNATURE_INVALID,	-EPERM},
+	{0x0,	0x0},
+};
+
+static int send_dbc_cmd(struct psp_dbc_device *dbc_dev,
+			enum psp_platform_access_msg msg)
+{
+	int ret;
+
+	dbc_dev->mbox->req.header.status = 0;
+	ret = psp_send_platform_access_msg(msg, (struct psp_request *)dbc_dev->mbox);
+	if (ret == -EIO) {
+		int i;
+
+		dev_dbg(dbc_dev->dev,
+			 "msg 0x%x failed with PSP error: 0x%x\n",
+			 msg, dbc_dev->mbox->req.header.status);
+
+		for (i = 0; error_codes[i].psp; i++) {
+			if (dbc_dev->mbox->req.header.status == error_codes[i].psp)
+				return error_codes[i].ret;
+		}
+	}
+
+	return ret;
+}
+
+static int send_dbc_nonce(struct psp_dbc_device *dbc_dev)
+{
+	int ret;
+
+	dbc_dev->mbox->req.header.payload_size = sizeof(dbc_dev->mbox->dbc_nonce);
+	ret = send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_GET_NONCE);
+	if (ret == -EAGAIN) {
+		dev_dbg(dbc_dev->dev, "retrying get nonce\n");
+		ret = send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_GET_NONCE);
+	}
+
+	return ret;
+}
+
+void dbc_dev_destroy(struct psp_device *psp)
+{
+	struct psp_dbc_device *dbc_dev = psp->dbc_data;
+
+	if (!dbc_dev)
+		return;
+
+	misc_deregister(&dbc_dev->char_dev);
+	mutex_destroy(&dbc_dev->ioctl_mutex);
+	psp->dbc_data = NULL;
+}
+
+static long dbc_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct psp_device *psp_master = psp_get_master_device();
+	void __user *argp = (void __user *)arg;
+	struct psp_dbc_device *dbc_dev;
+	int ret;
+
+	if (!psp_master || !psp_master->dbc_data)
+		return -ENODEV;
+	dbc_dev = psp_master->dbc_data;
+
+	mutex_lock(&dbc_dev->ioctl_mutex);
+
+	switch (cmd) {
+	case DBCIOCNONCE:
+		if (copy_from_user(&dbc_dev->mbox->dbc_nonce.user, argp,
+				   sizeof(struct dbc_user_nonce))) {
+			ret = -EFAULT;
+			goto unlock;
+		}
+
+		ret = send_dbc_nonce(dbc_dev);
+		if (ret)
+			goto unlock;
+
+		if (copy_to_user(argp, &dbc_dev->mbox->dbc_nonce.user,
+				 sizeof(struct dbc_user_nonce))) {
+			ret = -EFAULT;
+			goto unlock;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+
+	}
+unlock:
+	mutex_unlock(&dbc_dev->ioctl_mutex);
+
+	return ret;
+}
+
+static const struct file_operations dbc_fops = {
+	.owner	= THIS_MODULE,
+	.unlocked_ioctl = dbc_ioctl,
+};
+
+int dbc_dev_init(struct psp_device *psp)
+{
+	struct device *dev = psp->dev;
+	struct psp_dbc_device *dbc_dev;
+	int ret;
+
+	if (!PSP_FEATURE(psp, DBC))
+		return 0;
+
+	dbc_dev = devm_kzalloc(dev, sizeof(*dbc_dev), GFP_KERNEL);
+	if (!dbc_dev)
+		return -ENOMEM;
+
+	BUILD_BUG_ON(sizeof(union dbc_buffer) > PAGE_SIZE);
+	dbc_dev->mbox = (void *)devm_get_free_pages(dev, GFP_KERNEL, 0);
+	if (!dbc_dev->mbox) {
+		ret = -ENOMEM;
+		goto cleanup_dev;
+	}
+
+	psp->dbc_data = dbc_dev;
+	dbc_dev->dev = dev;
+
+	ret = send_dbc_nonce(dbc_dev);
+	if (ret == -EACCES) {
+		dev_dbg(dbc_dev->dev,
+			"dynamic boost control was previously authenticated\n");
+		ret = 0;
+	}
+	dev_dbg(dbc_dev->dev, "dynamic boost control is %savailable\n",
+		ret ? "un" : "");
+	if (ret) {
+		ret = 0;
+		goto cleanup_mbox;
+	}
+
+	dbc_dev->char_dev.minor = MISC_DYNAMIC_MINOR;
+	dbc_dev->char_dev.name = "dbc";
+	dbc_dev->char_dev.fops = &dbc_fops;
+	dbc_dev->char_dev.mode = 0600;
+	ret = misc_register(&dbc_dev->char_dev);
+	if (ret)
+		goto cleanup_mbox;
+
+	mutex_init(&dbc_dev->ioctl_mutex);
+
+	return 0;
+
+cleanup_mbox:
+	devm_free_pages(dev, (unsigned long)dbc_dev->mbox);
+
+cleanup_dev:
+	psp->dbc_data = NULL;
+	devm_kfree(dev, dbc_dev);
+
+	return ret;
+}

drivers/crypto/ccp/dbc.h

@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * AMD Platform Security Processor (PSP) Dynamic Boost Control support
+ *
+ * Copyright (C) 2023 Advanced Micro Devices, Inc.
+ *
+ * Author: Mario Limonciello <mario.limonciello@amd.com>
+ */
+
+#ifndef __DBC_H__
+#define __DBC_H__
+
+#include <uapi/linux/psp-dbc.h>
+
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/psp-platform-access.h>
+
+#include "psp-dev.h"
+
+struct psp_dbc_device {
+	struct device *dev;
+
+	union dbc_buffer *mbox;
+
+	struct mutex ioctl_mutex;
+
+	struct miscdevice char_dev;
+};
+
+struct dbc_nonce {
+	struct psp_req_buffer_hdr	header;
+	struct dbc_user_nonce		user;
+} __packed;
+
+union dbc_buffer {
+	struct psp_request		req;
+	struct dbc_nonce		dbc_nonce;
+};
+
+void dbc_dev_destroy(struct psp_device *psp);
+int dbc_dev_init(struct psp_device *psp);
+
+#endif /* __DBC_H */

drivers/crypto/ccp/psp-dev.c

@@ -15,6 +15,7 @@
 #include "sev-dev.h"
 #include "tee-dev.h"
 #include "platform-access.h"
+#include "dbc.h"
 
 struct psp_device *psp_master;
 
@@ -112,6 +113,12 @@ static void psp_init_platform_access(struct psp_device *psp)
 		dev_warn(psp->dev, "platform access init failed: %d\n", ret);
 		return;
 	}
+
+	/* dbc must come after platform access as it tests the feature */
+	ret = dbc_dev_init(psp);
+	if (ret)
+		dev_warn(psp->dev, "failed to init dynamic boost control: %d\n",
+			 ret);
 }
 
 static int psp_init(struct psp_device *psp)
@@ -217,6 +224,8 @@ void psp_dev_destroy(struct sp_device *sp)
 
 	tee_dev_destroy(psp);
 
+	dbc_dev_destroy(psp);
+
 	platform_access_dev_destroy(psp);
 
 	sp_free_psp_irq(sp, psp);

drivers/crypto/ccp/psp-dev.h

@@ -40,6 +40,7 @@ struct psp_device {
 	void *sev_data;
 	void *tee_data;
 	void *platform_access_data;
+	void *dbc_data;
 
 	unsigned int capability;
 };

drivers/crypto/ccp/sp-dev.h

@@ -28,6 +28,10 @@
 #define CACHE_NONE			0x00
 #define CACHE_WB_NO_ALLOC		0xb7
 
+#define PLATFORM_FEATURE_DBC		0x1
+
+#define PSP_FEATURE(psp, feat)	(psp->vdata && psp->vdata->platform_features & PLATFORM_FEATURE_##feat)
+
 /* Structure to hold CCP device data */
 struct ccp_device;
 struct ccp_vdata {
@@ -71,6 +75,7 @@ struct psp_vdata {
 	const unsigned int inten_reg;
 	const unsigned int intsts_reg;
 	const unsigned int bootloader_info_reg;
+	const unsigned int platform_features;
 };
 
 /* Structure to hold SP device data */

drivers/crypto/ccp/sp-pci.c

@@ -470,6 +470,7 @@ static const struct psp_vdata pspv3 = {
 	.feature_reg		= 0x109fc,	/* C2PMSG_63 */
 	.inten_reg		= 0x10690,	/* P2CMSG_INTEN */
 	.intsts_reg		= 0x10694,	/* P2CMSG_INTSTS */
+	.platform_features	= PLATFORM_FEATURE_DBC,
 };
 
 static const struct psp_vdata pspv4 = {

include/linux/psp-platform-access.h

@@ -8,6 +8,7 @@
 enum psp_platform_access_msg {
 	PSP_CMD_NONE = 0x0,
 	PSP_I2C_REQ_BUS_CMD = 0x64,
+	PSP_DYNAMIC_BOOST_GET_NONCE,
 };
 
 struct psp_req_buffer_hdr {

include/uapi/linux/psp-dbc.h

@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+ * Userspace interface for AMD Dynamic Boost Control (DBC)
+ *
+ * Copyright (C) 2023 Advanced Micro Devices, Inc.
+ *
+ * Author: Mario Limonciello <mario.limonciello@amd.com>
+ */
+
+#ifndef __PSP_DBC_USER_H__
+#define __PSP_DBC_USER_H__
+
+#include <linux/types.h>
+
+/**
+ * DOC: AMD Dynamic Boost Control (DBC) interface
+ */
+
+#define DBC_NONCE_SIZE		16
+#define DBC_SIG_SIZE		32
+
+/**
+ * struct dbc_user_nonce - Nonce exchange structure (input/output).
+ * @auth_needed: Whether the PSP should authenticate this request (input).
+ *               0: no authentication, PSP will return single use nonce.
+ *               1: authentication: PSP will return multi-use nonce.
+ * @nonce:       8 byte value used for future authentication (output).
+ * @signature:   Optional 32 byte signature created by software using a
+ *               previous nonce (input).
+ */
+struct dbc_user_nonce {
+	__u32	auth_needed;
+	__u8	nonce[DBC_NONCE_SIZE];
+	__u8	signature[DBC_SIG_SIZE];
+} __packed;
+
+/**
+ * Dynamic Boost Control (DBC) IOC
+ *
+ * possible return codes for all DBC IOCTLs:
+ *  0:          success
+ *  -EINVAL:    invalid input
+ *  -E2BIG:     excess data passed
+ *  -EFAULT:    failed to copy to/from userspace
+ *  -EBUSY:     mailbox in recovery or in use
+ *  -ENODEV:    driver not bound with PSP device
+ *  -EACCES:    request isn't authorized
+ *  -EINVAL:    invalid parameter
+ *  -ETIMEDOUT: request timed out
+ *  -EAGAIN:    invalid request for state machine
+ *  -ENOENT:    not implemented
+ *  -ENFILE:    overflow
+ *  -EPERM:     invalid signature
+ *  -EIO:       unknown error
+ */
+#define DBC_IOC_TYPE	'D'
+
+/**
+ * DBCIOCNONCE - Fetch a nonce from the PSP for authenticating commands.
+ *               If a nonce is fetched without authentication it can only
+ *               be utilized for one command.
+ *               If a nonce is fetched with authentication it can be used
+ *               for multiple requests.
+ */
+#define DBCIOCNONCE	_IOWR(DBC_IOC_TYPE, 0x1, struct dbc_user_nonce)
+
+#endif /* __PSP_DBC_USER_H__ */