Re: [PATCH v5] misc: Add Nitro Secure Module driver

[Michael S. Tsirkin]

On Tue, Oct 10, 2023 at 07:18:15PM +0000, Alexander Graf wrote:
> When running Linux inside a Nitro Enclave, the hypervisor provides a
> special virtio device called "Nitro Security Module" (NSM). This device
> has 3 main functions:
> 
>   1) Provide attestation reports
>   2) Modify PCR state
>   3) Provide entropy
> 
> This patch adds a driver for NSM that exposes a /dev/nsm device node which
> user space can issue an ioctl on this device with raw NSM CBOR formatted
> commands to request attestation documents, influence PCR states, read
> entropy and enumerate status of the device. In addition, the driver
> implements a hwrng backend.
> 
> Originally-by: Petre Eftime <petre.eftime@xxxxxxxxx>
> Signed-off-by: Alexander Graf <graf@xxxxxxxxxx>

Could some documentation about how this device works be posted on virtio
list please?


> ---
> 
> v1 -> v2:
> 
>   - Remove boilerplate
>   - Add uapi header
> 
> v2 -> v3:
> 
>   - Move globals to device struct
>   - Add compat handling
>   - Simplify some naming
>   - Remove debug prints
>   - Use module_virtio_driver
>   - Drop use of uio.h
> 
> v3 -> v4:
> 
>   - Merge hwrng into the misc driver
>   - Add dependency on CBOR library
>   - Add internal and ioctl logic for all current NSM actions
>   - Use in-struct arrays instead of kvecs
>   - Add sysfs entries for NSM metadata
>   - Use dev_ print and devm_ allocation helpers
> 
> v4 -> v5:
> 
>   - Remove CBOR parsing and generation again
>   - Remove support for any non-raw ioctls
> ---
>  MAINTAINERS              |   9 +
>  drivers/misc/Kconfig     |  13 +
>  drivers/misc/Makefile    |   1 +
>  drivers/misc/nsm.c       | 576 +++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/nsm.h |  31 +++
>  5 files changed, 630 insertions(+)
>  create mode 100644 drivers/misc/nsm.c
>  create mode 100644 include/uapi/linux/nsm.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6c4cce45a09d..d7afb3dedbd2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15096,6 +15096,15 @@ F:	include/linux/nitro_enclaves.h
>  F:	include/uapi/linux/nitro_enclaves.h
>  F:	samples/nitro_enclaves/
>  
> +NITRO SECURE MODULE (NSM)
> +M:	Alexander Graf <graf@xxxxxxxxxx>
> +L:	linux-kernel@xxxxxxxxxxxxxxx
> +L:	The AWS Nitro Enclaves Team <aws-nitro-enclaves-devel@xxxxxxxxxx>
> +S:	Supported
> +W:	https://aws.amazon.com/ec2/nitro/nitro-enclaves/
> +F:	drivers/misc/nsm.c
> +F:	include/uapi/linux/nsm.h
> +
>  NOHZ, DYNTICKS SUPPORT
>  M:	Frederic Weisbecker <frederic@xxxxxxxxxx>
>  M:	Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index cadd4a820c03..236f36a8e8d4 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -562,6 +562,19 @@ config TPS6594_PFSM
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called tps6594-pfsm.
>  
> +config NSM
> +	tristate "Nitro (Enclaves) Security Module support"
> +	depends on VIRTIO
> +	select HW_RANDOM
> +	select CBOR
> +	help
> +	  This driver provides support for the Nitro Security Module
> +	  in AWS EC2 Nitro based Enclaves. The driver exposes a /dev/nsm
> +	  device user space can use to communicate with the hypervisor.
> +
> +	  To compile this driver as a module, choose M here.
> +	  The module will be called nsm.
> +
>  source "drivers/misc/c2port/Kconfig"
>  source "drivers/misc/eeprom/Kconfig"
>  source "drivers/misc/cb710/Kconfig"
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index f2a4d1ff65d4..ea6ea5bbbc9c 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -67,3 +67,4 @@ obj-$(CONFIG_TMR_MANAGER)      += xilinx_tmr_manager.o
>  obj-$(CONFIG_TMR_INJECT)	+= xilinx_tmr_inject.o
>  obj-$(CONFIG_TPS6594_ESM)	+= tps6594-esm.o
>  obj-$(CONFIG_TPS6594_PFSM)	+= tps6594-pfsm.o
> +obj-$(CONFIG_NSM)		+= nsm.o
> diff --git a/drivers/misc/nsm.c b/drivers/misc/nsm.c
> new file mode 100644
> index 000000000000..7ead36ba412f
> --- /dev/null
> +++ b/drivers/misc/nsm.c
> @@ -0,0 +1,576 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Amazon Nitro Secure Module driver.
> + *
> + * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
> + *
> + * The Nitro Secure Module implements commands via CBOR over virtio.
> + * This driver exposes a raw message ioctls on /dev/nsm that user
> + * space can use to issue these commands.
> + */
> +
> +#include <linux/file.h>
> +#include <linux/fs.h>
> +#include <linux/interrupt.h>
> +#include <linux/hw_random.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/uaccess.h>
> +#include <linux/uio.h>
> +#include <linux/virtio_config.h>
> +#include <linux/virtio_ids.h>
> +#include <linux/virtio.h>
> +#include <linux/wait.h>
> +#include <uapi/linux/nsm.h>
> +
> +/* Timeout for NSM virtqueue respose in milliseconds. */
> +#define NSM_DEFAULT_TIMEOUT_MSECS (120000) /* 2 minutes */
> +
> +struct nsm {
> +	struct list_head      node;
> +	struct virtio_device *vdev;
> +	struct virtqueue     *vq;
> +	struct mutex          lock;
> +	wait_queue_head_t     wq;
> +	bool                  device_notified;
> +	struct miscdevice     misc;
> +	struct hwrng          hwrng;
> +	struct work_struct    misc_init;
> +};
> +
> +/* NSM device ID */
> +static const struct virtio_device_id id_table[] = {
> +	{ VIRTIO_ID_NITRO_SEC_MOD, VIRTIO_DEV_ANY_ID },
> +	{ 0 },
> +};
> +
> +/* Maximum length input data */
> +struct nsm_data_req {
> +	__u32 len;
> +	__u8  data[NSM_REQUEST_MAX_SIZE];
> +};
> +
> +/* Maximum length output data */
> +struct nsm_data_resp {
> +	__u32 len;
> +	__u8  data[NSM_RESPONSE_MAX_SIZE];
> +};
> +
> +/* Full NSM request/response message */
> +struct nsm_msg {
> +	struct nsm_data_req req;
> +	struct nsm_data_resp resp;
> +};
> +
> +static inline struct nsm *file_to_nsm(struct file *file)
> +{
> +	return container_of(file->private_data, struct nsm, misc);
> +}
> +
> +static inline struct nsm *hwrng_to_nsm(struct hwrng *rng)
> +{
> +	return container_of(rng, struct nsm, hwrng);
> +}
> +
> +static inline struct nsm *misc_dev_to_nsm(struct miscdevice *misc)
> +{
> +	return container_of(misc, struct nsm, misc);
> +}
> +
> +#define CBOR_TYPE_MASK  0xE0
> +#define CBOR_TYPE_MAP 0xA0
> +#define CBOR_TYPE_TEXT 0x60
> +#define CBOR_TYPE_ARRAY 0x40
> +#define CBOR_HEADER_SIZE_SHORT 1
> +
> +#define CBOR_SHORT_SIZE_MAX_VALUE 23
> +#define CBOR_LONG_SIZE_U8  24
> +#define CBOR_LONG_SIZE_U16 25
> +#define CBOR_LONG_SIZE_U32 26
> +#define CBOR_LONG_SIZE_U64 27
> +
> +#define CBOR_HEADER_SIZE_U8  (CBOR_HEADER_SIZE_SHORT + sizeof(u8))
> +#define CBOR_HEADER_SIZE_U16 (CBOR_HEADER_SIZE_SHORT + sizeof(u16))
> +#define CBOR_HEADER_SIZE_U32 (CBOR_HEADER_SIZE_SHORT + sizeof(u32))
> +#define CBOR_HEADER_SIZE_U64 (CBOR_HEADER_SIZE_SHORT + sizeof(u64))
> +
> +static bool cbor_object_is_array(const u8 *cbor_object, size_t cbor_object_size)
> +{
> +	if (cbor_object_size == 0 || cbor_object == NULL)
> +		return false;
> +
> +	return (cbor_object[0] & CBOR_TYPE_MASK) == CBOR_TYPE_ARRAY;
> +}
> +
> +static int cbor_object_get_array(u8 *cbor_object, size_t cbor_object_size, u8 **cbor_array)
> +{
> +	u8 cbor_short_size;
> +	u64 array_len;
> +	u64 array_offset;
> +
> +	if (!cbor_object_is_array(cbor_object, cbor_object_size))
> +		return -EFAULT;
> +
> +	if (cbor_array == NULL)
> +		return -EFAULT;
> +
> +	cbor_short_size = (cbor_object[0] & 0x1F);
> +
> +	/* Decoding byte array length */
> +	/* In short field encoding, the object header is 1 byte long and
> +	 * contains the type on the 3 MSB and the length on the LSB.
> +	 * If the length in the LSB is larger than 23, then the object
> +	 * uses long field encoding, and will contain the length over the
> +	 * next bytes in the object, depending on the value:
> +	 * 24 is u8, 25 is u16, 26 is u32 and 27 is u64.
> +	 */
> +	if (cbor_short_size <= CBOR_SHORT_SIZE_MAX_VALUE) {
> +		/* short encoding */
> +		array_len = cbor_short_size;
> +		array_offset = CBOR_HEADER_SIZE_SHORT;
> +	} else if (cbor_short_size == CBOR_LONG_SIZE_U8) {
> +		if (cbor_object_size < CBOR_HEADER_SIZE_U8)
> +			return -EFAULT;
> +		/* 1 byte */
> +		array_len = cbor_object[1];
> +		array_offset = CBOR_HEADER_SIZE_U8;
> +	} else if (cbor_short_size == CBOR_LONG_SIZE_U16) {
> +		if (cbor_object_size < CBOR_HEADER_SIZE_U16)
> +			return -EFAULT;
> +		/* 2 bytes */
> +		array_len = cbor_object[1] << 8 | cbor_object[2];
> +		array_offset = CBOR_HEADER_SIZE_U16;
> +	} else if (cbor_short_size == CBOR_LONG_SIZE_U32) {
> +		if (cbor_object_size < CBOR_HEADER_SIZE_U32)
> +			return -EFAULT;
> +		/* 4 bytes */
> +		array_len = cbor_object[1] << 24 |
> +			cbor_object[2] << 16 |
> +			cbor_object[3] << 8  |
> +			cbor_object[4];
> +		array_offset = CBOR_HEADER_SIZE_U32;
> +	} else if (cbor_short_size == CBOR_LONG_SIZE_U64) {
> +		if (cbor_object_size < CBOR_HEADER_SIZE_U64)
> +			return -EFAULT;
> +		/* 8 bytes */
> +		array_len = (u64) cbor_object[1] << 56 |
> +			  (u64) cbor_object[2] << 48 |
> +			  (u64) cbor_object[3] << 40 |
> +			  (u64) cbor_object[4] << 32 |
> +			  (u64) cbor_object[5] << 24 |
> +			  (u64) cbor_object[6] << 16 |
> +			  (u64) cbor_object[7] << 8  |
> +			  (u64) cbor_object[8];
> +		array_offset = CBOR_HEADER_SIZE_U64;
> +	}
> +
> +	if (cbor_object_size < array_offset)
> +		return -EFAULT;
> +
> +	if (cbor_object_size - array_offset < array_len)
> +		return -EFAULT;
> +
> +	if (array_len > INT_MAX)
> +		return -EFAULT;
> +
> +	*cbor_array = cbor_object + array_offset;
> +	return array_len;
> +}
> +
> +/* Copy the request of a raw message to kernel space */
> +static int fill_req_raw(struct nsm *nsm, struct nsm_data_req *req,
> +			struct nsm_raw *raw)
> +{
> +	/* Verify the user input size. */
> +	if (raw->request.len > sizeof(req->data))
> +		return -EMSGSIZE;
> +
> +	/* Copy the request payload */
> +	if (copy_from_user(req->data, u64_to_user_ptr(raw->request.addr),
> +			   raw->request.len))
> +		return -EFAULT;
> +
> +	req->len = raw->request.len;
> +
> +	return 0;
> +}
> +
> +/* Copy the response of a raw message back to user-space */
> +static int parse_resp_raw(struct nsm *nsm, struct nsm_data_resp *resp,
> +			  struct nsm_raw *raw)
> +{
> +	/* Truncate any message that does not fit. */
> +	raw->response.len = min_t(u64, raw->response.len, resp->len);
> +
> +	/* Copy the response content to user space */
> +	if (copy_to_user(u64_to_user_ptr(raw->response.addr),
> +			 resp->data, raw->response.len))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +/* Virtqueue interrupt handler */
> +static void nsm_vq_callback(struct virtqueue *vq)
> +{
> +	struct nsm *nsm = vq->vdev->priv;
> +
> +	nsm->device_notified = true;
> +	wake_up(&nsm->wq);
> +}
> +
> +/* Forward a message to the NSM device and wait for the response from it */
> +static int nsm_sendrecv_msg(struct nsm *nsm, struct nsm_msg *msg)
> +{
> +	struct device *dev = &nsm->vdev->dev;
> +	struct scatterlist sg_in, sg_out;
> +	struct virtqueue *vq = nsm->vq;
> +	unsigned int len;
> +	void *queue_buf;
> +	bool kicked;
> +	int rc;
> +
> +	/* Initialize scatter-gather lists with request and response buffers. */
> +	sg_init_one(&sg_out, msg->req.data, msg->req.len);
> +	sg_init_one(&sg_in, msg->resp.data, sizeof(msg->resp.data));
> +
> +	mutex_lock(&nsm->lock);
> +
> +	/* Add the request buffer (read by the device). */
> +	rc = virtqueue_add_outbuf(vq, &sg_out, 1, msg->req.data, GFP_KERNEL);
> +	if (rc) {
> +		mutex_unlock(&nsm->lock);
> +		return rc;
> +	}
> +
> +	/* Add the response buffer (written by the device). */
> +	rc = virtqueue_add_inbuf(vq, &sg_in, 1, msg->resp.data, GFP_KERNEL);
> +	if (rc)
> +		goto cleanup;
> +
> +	nsm->device_notified = false;
> +	kicked = virtqueue_kick(vq);
> +	if (!kicked) {
> +		/* Cannot kick the virtqueue. */
> +		rc = -EIO;
> +		goto cleanup;
> +	}
> +
> +	/* If the kick succeeded, wait for the device's response. */
> +	rc = wait_event_timeout(nsm->wq,
> +		nsm->device_notified == true,
> +		msecs_to_jiffies(NSM_DEFAULT_TIMEOUT_MSECS));
> +	if (!rc) {
> +		rc = -ETIMEDOUT;
> +		goto cleanup;
> +	}
> +
> +	queue_buf = virtqueue_get_buf(vq, &len);
> +	if (!queue_buf || (queue_buf != msg->req.data)) {
> +		dev_err(dev, "wrong request buffer.");
> +		rc = -ENODATA;
> +		goto cleanup;
> +	}
> +
> +	queue_buf = virtqueue_get_buf(vq, &len);
> +	if (!queue_buf || (queue_buf != msg->resp.data)) {
> +		dev_err(dev, "wrong response buffer.");
> +		rc = -ENODATA;
> +		goto cleanup;
> +	}
> +
> +	msg->resp.len = len;
> +
> +	rc = 0;
> +
> +cleanup:
> +	if (rc) {
> +		/* Clean the virtqueue. */
> +		while (virtqueue_get_buf(vq, &len) != NULL)
> +			;
> +	}
> +
> +	mutex_unlock(&nsm->lock);
> +	return rc;
> +}
> +
> +static int fill_req_get_random(struct nsm *nsm, struct nsm_data_req *req)
> +{
> +	/*
> +	 * 69                          # text(9)
> +	 *     47657452616E646F6D      # "GetRandom"
> +	 */
> +	const u8 request[] = { CBOR_TYPE_TEXT + strlen("GetRandom"),
> +			       'G', 'e', 't', 'R', 'a', 'n', 'd', 'o', 'm' };
> +
> +	memcpy(req->data, request, sizeof(request));
> +	req->len = sizeof(request);
> +
> +	return 0;
> +}
> +
> +static int parse_resp_get_random(struct nsm *nsm, struct nsm_data_resp *resp,
> +				 void *out, size_t max)
> +{
> +	/*
> +	 * A1                          # map(1)
> +	 *     69                      # text(9) - Name of field
> +	 *         47657452616E646F6D  # "GetRandom"
> +	 * A1                          # map(1) - The field itself
> +	 *     66                      # text(6)
> +	 *         72616E646F6D        # "random"
> +	 *	# The rest of the response is random data
> +	 */
> +	const u8 response[] = { CBOR_TYPE_MAP + 1,
> +				CBOR_TYPE_TEXT + strlen("GetRandom"),
> +				'G', 'e', 't', 'R', 'a', 'n', 'd', 'o', 'm',
> +				CBOR_TYPE_MAP + 1,
> +				CBOR_TYPE_TEXT + strlen("random"),
> +				'r', 'a', 'n', 'd', 'o', 'm' };
> +	struct device *dev = &nsm->vdev->dev;
> +	u8 *rand_data = NULL;
> +	u8 *resp_ptr = resp->data;
> +	u64 resp_len = resp->len;
> +	int rc;
> +
> +	if ((resp->len < sizeof(response) + 1) ||
> +	    (memcmp(resp_ptr, response, sizeof(response)) != 0)) {
> +		dev_err(dev, "Invalid response for GetRandom");
> +		return -EFAULT;
> +	}
> +
> +	resp_ptr += sizeof(response);
> +	resp_len -= sizeof(response);
> +
> +	if (!cbor_object_is_array(resp_ptr, resp_len)) {
> +		/* not a byte array */
> +		dev_err(dev, "GetRandom: Not a byte array");
> +		return -EFAULT;
> +	}
> +
> +	rc = cbor_object_get_array(resp_ptr, resp_len, &rand_data);
> +	if (rc < 0) {
> +		dev_err(dev, "GetRandom: Invalid CBOR encoding\n");
> +		return rc;
> +	}
> +
> +	rc = min_t(size_t, rc, max);
> +	memcpy(out, rand_data, rc);
> +
> +	return rc;
> +}
> +
> +/*
> + * HwRNG implementation
> + */
> +static int nsm_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
> +{
> +	struct nsm *nsm = hwrng_to_nsm(rng);
> +	struct device *dev = &nsm->vdev->dev;
> +	struct nsm_msg *msg;
> +	int rc = 0;
> +
> +	/* NSM always needs to wait for a response */
> +	if (!wait)
> +		return 0;
> +
> +	msg = devm_kzalloc(dev, sizeof(*msg), GFP_KERNEL);
> +	if (!msg)
> +		return -ENOMEM;
> +
> +	rc = fill_req_get_random(nsm, &msg->req);
> +	if (rc != 0)
> +		goto out;
> +
> +	rc = nsm_sendrecv_msg(nsm, msg);
> +	if (rc != 0)
> +		goto out;
> +
> +	rc = parse_resp_get_random(nsm, &msg->resp, data, max);
> +	if (rc < 0)
> +		goto out;
> +
> +	dev_dbg(dev, "RNG: returning rand bytes = %d", rc);
> +out:
> +	devm_kfree(dev, msg);
> +	return rc;
> +}
> +
> +static long nsm_dev_ioctl(struct file *file, unsigned int cmd,
> +	unsigned long arg)
> +{
> +	void __user *argp = u64_to_user_ptr((u64)arg);
> +	struct nsm *nsm = file_to_nsm(file);
> +	struct device *dev = &nsm->vdev->dev;
> +	struct nsm_msg *msg;
> +	struct nsm_raw raw;
> +	int r = 0;
> +
> +	if (cmd != NSM_IOCTL_RAW)
> +		return -EINVAL;
> +
> +	if (_IOC_SIZE(cmd) != sizeof(raw))
> +		return -EINVAL;
> +
> +	/* Allocate message buffers to device */
> +	r = -ENOMEM;
> +	msg = devm_kzalloc(dev, sizeof(*msg), GFP_KERNEL);
> +	if (!msg)
> +		goto out;
> +
> +	/* Copy user argument struct to kernel argument struct */
> +	r = -EFAULT;
> +	if (copy_from_user(&raw, argp, _IOC_SIZE(cmd)))
> +		goto out;
> +
> +	/* Convert kernel argument struct to device request */
> +	r = fill_req_raw(nsm, &msg->req, &raw);
> +	if (r)
> +		goto out;
> +
> +	/* Send message to NSM and read reply */
> +	r = nsm_sendrecv_msg(nsm, msg);
> +	if (r)
> +		goto out;
> +
> +	/* Parse device response into kernel argument struct */
> +	r = parse_resp_raw(nsm, &msg->resp, &raw);
> +	if (r)
> +		goto out;
> +
> +	/* Copy kernel argument struct back to user argument struct */
> +	r = -EFAULT;
> +	if (copy_to_user(argp, &raw, sizeof(raw)))
> +		goto out;
> +
> +	r = 0;
> +
> +out:
> +	devm_kfree(dev, msg);
> +	return r;
> +}
> +
> +static int nsm_dev_file_open(struct inode *node, struct file *file)
> +{
> +	return 0;
> +}
> +
> +static int nsm_dev_file_close(struct inode *inode, struct file *file)
> +{
> +	return 0;
> +}
> +
> +static int nsm_device_init_vq(struct virtio_device *vdev)
> +{
> +	struct virtqueue *vq = virtio_find_single_vq(vdev,
> +		nsm_vq_callback, "nsm.vq.0");
> +	struct nsm *nsm = vdev->priv;
> +
> +	if (IS_ERR(vq))
> +		return PTR_ERR(vq);
> +
> +	nsm->vq = vq;
> +
> +	return 0;
> +}
> +
> +static const struct file_operations nsm_dev_fops = {
> +	.open = nsm_dev_file_open,
> +	.release = nsm_dev_file_close,
> +	.unlocked_ioctl = nsm_dev_ioctl,
> +	.compat_ioctl = compat_ptr_ioctl,
> +};
> +
> +/* Handler for probing the NSM device */
> +static int nsm_device_probe(struct virtio_device *vdev)
> +{
> +	struct device *dev = &vdev->dev;
> +	struct nsm *nsm;
> +	int rc;
> +
> +	nsm = devm_kzalloc(&vdev->dev, sizeof(*nsm), GFP_KERNEL);
> +	if (!nsm)
> +		return -ENOMEM;
> +
> +	vdev->priv = nsm;
> +	nsm->vdev = vdev;
> +
> +	rc = nsm_device_init_vq(vdev);
> +	if (rc) {
> +		dev_err(dev, "queue failed to initialize: %d.\n", rc);
> +		goto err_init_vq;
> +	}
> +
> +	mutex_init(&nsm->lock);
> +	init_waitqueue_head(&nsm->wq);
> +
> +	/* Register as hwrng provider */
> +	nsm->hwrng = (struct hwrng) {
> +		.read = nsm_rng_read,
> +		.name = "nsm-hwrng",
> +		.quality = 1000,
> +	};
> +
> +	rc = devm_hwrng_register(&vdev->dev, &nsm->hwrng);
> +	if (rc) {
> +		dev_err(dev, "RNG initialization error: %d.\n", rc);
> +		goto err_hwrng;
> +	}
> +
> +	/* Register /dev/nsm device node */
> +	nsm->misc = (struct miscdevice) {
> +		.minor	= MISC_DYNAMIC_MINOR,
> +		.name	= "nsm",
> +		.fops	= &nsm_dev_fops,
> +		.mode	= 0666,
> +	};
> +
> +	rc = misc_register(&nsm->misc);
> +	if (rc) {
> +		dev_err(dev, "misc device registration error: %d.\n", rc);
> +		goto err_misc;
> +	}
> +
> +	return 0;
> +
> +err_misc:
> +	hwrng_unregister(&nsm->hwrng);
> +err_hwrng:
> +	vdev->config->del_vqs(vdev);
> +err_init_vq:
> +	kfree(nsm);
> +	return rc;
> +}
> +
> +/* Handler for removing the NSM device */
> +static void nsm_device_remove(struct virtio_device *vdev)
> +{
> +	struct nsm *nsm = vdev->priv;
> +
> +	hwrng_unregister(&nsm->hwrng);
> +
> +	vdev->config->del_vqs(vdev);
> +	misc_deregister(&nsm->misc);
> +	list_del(&nsm->node);
> +}
> +
> +/* NSM device configuration structure */
> +static struct virtio_driver virtio_nsm_driver = {
> +	.feature_table             = 0,
> +	.feature_table_size        = 0,
> +	.feature_table_legacy      = 0,
> +	.feature_table_size_legacy = 0,
> +	.driver.name               = KBUILD_MODNAME,
> +	.driver.owner              = THIS_MODULE,
> +	.id_table                  = id_table,
> +	.probe                     = nsm_device_probe,
> +	.remove                    = nsm_device_remove,
> +};
> +
> +module_virtio_driver(virtio_nsm_driver);
> +MODULE_DEVICE_TABLE(virtio, id_table);
> +MODULE_DESCRIPTION("Virtio NSM driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/uapi/linux/nsm.h b/include/uapi/linux/nsm.h
> new file mode 100644
> index 000000000000..e529f232f6c0
> --- /dev/null
> +++ b/include/uapi/linux/nsm.h
> @@ -0,0 +1,31 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
> + */
> +
> +#ifndef __UAPI_LINUX_NSM_H
> +#define __UAPI_LINUX_NSM_H
> +
> +#include <linux/ioctl.h>
> +#include <linux/types.h>
> +
> +#define NSM_MAGIC		0x0A
> +
> +#define NSM_REQUEST_MAX_SIZE	0x1000
> +#define NSM_RESPONSE_MAX_SIZE	0x3000
> +
> +struct nsm_iovec {
> +	__u64 addr; /* Virtual address of target buffer */
> +	__u64 len;  /* Length of target buffer */
> +};
> +
> +/* Raw NSM message. Only available with CAP_SYS_ADMIN. */
> +struct nsm_raw {
> +	/* Request from user */
> +	struct nsm_iovec request;
> +	/* Response to user */
> +	struct nsm_iovec response;
> +};
> +#define NSM_IOCTL_RAW		_IOWR(NSM_MAGIC, 0x0, struct nsm_raw)
> +
> +#endif /* __UAPI_LINUX_NSM_H */
> -- 
> 2.40.1
> 
> 
> 
> 
> Amazon Development Center Germany GmbH
> Krausenstr. 38
> 10117 Berlin
> Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
> Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
> Sitz: Berlin
> Ust-ID: DE 289 237 879
> 
>