Subject: Re: [PATCH 08/10] nvdimm: Add driver for OpenCAPI Storage Class Memory

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Mon, 11 Nov 2019 16:44:19 +0530

"Alastair D'Silva" <[email-masked]> writes:

> From: Alastair D'Silva <[email-masked]>
>
> This driver exposes LPC memory on OpenCAPI SCM cards
> as an NVDIMM, allowing the existing nvram infrastructure
> to be used.
>
> Signed-off-by: Alastair D'Silva <[email-masked]>
> ---
>  drivers/nvdimm/Kconfig             |   17 +
>  drivers/nvdimm/Makefile            |    3 +
>  drivers/nvdimm/ocxl-scm.c          | 2210 ++++++++++++++++++++++++++++
>  drivers/nvdimm/ocxl-scm_internal.c |  232 +++
>  drivers/nvdimm/ocxl-scm_internal.h |  331 +++++
>  drivers/nvdimm/ocxl-scm_sysfs.c    |  219 +++
>  include/uapi/linux/ocxl-scm.h      |  128 ++
>  mm/memory_hotplug.c                |    2 +-
>  8 files changed, 3141 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/nvdimm/ocxl-scm.c
>  create mode 100644 drivers/nvdimm/ocxl-scm_internal.c
>  create mode 100644 drivers/nvdimm/ocxl-scm_internal.h
>  create mode 100644 drivers/nvdimm/ocxl-scm_sysfs.c
>  create mode 100644 include/uapi/linux/ocxl-scm.h
>
> diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
> index 36af7af6b7cf..e4f7b6b08efd 100644
> --- a/drivers/nvdimm/Kconfig
> +++ b/drivers/nvdimm/Kconfig
> @@ -130,4 +130,21 @@ config NVDIMM_TEST_BUILD
>  	  core devm_memremap_pages() implementation and other
>  	  infrastructure.
>  
> +config OCXL_SCM
> +	tristate "OpenCAPI Storage Class Memory"
> +	depends on LIBNVDIMM
> +	select ZONE_DEVICE
> +	select OCXL
> +	help
> +	  Exposes devices that implement the OpenCAPI Storage Class Memory
> +	  specification as persistent memory regions.
> +
> +	  Select N if unsure.
> +
> +config OCXL_SCM_DEBUG
> +	bool "OpenCAPI Storage Class Memory debugging"
> +	depends on OCXL_SCM
> +	help
> +	  Enables low level IOCTLs for OpenCAPI SCM firmware development
> +
>  endif
> diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
> index 29203f3d3069..43d826397bfc 100644
> --- a/drivers/nvdimm/Makefile
> +++ b/drivers/nvdimm/Makefile
> @@ -6,6 +6,9 @@ obj-$(CONFIG_ND_BLK) += nd_blk.o
>  obj-$(CONFIG_X86_PMEM_LEGACY) += nd_e820.o
>  obj-$(CONFIG_OF_PMEM) += of_pmem.o
>  obj-$(CONFIG_VIRTIO_PMEM) += virtio_pmem.o nd_virtio.o
> +obj-$(CONFIG_OCXL_SCM) += ocxlscm.o
> +
> +ocxlscm-y := ocxl-scm.o ocxl-scm_internal.o ocxl-scm_sysfs.o
>  
>  nd_pmem-y := pmem.o
>  
> diff --git a/drivers/nvdimm/ocxl-scm.c b/drivers/nvdimm/ocxl-scm.c
> new file mode 100644
> index 000000000000..f4e6cc022de8
> --- /dev/null
> +++ b/drivers/nvdimm/ocxl-scm.c

how about drivers/nvdimm/ocxl/scm.c ? Or may be place the driver as an
ocxl driver.

> @@ -0,0 +1,2210 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +// Copyright 2019 IBM Corp.
> +
> +/*
> + * A driver for Storage Class Memory, connected via OpenCAPI
> + */
> +
> +#include <linux/module.h>
> +#include <misc/ocxl.h>
> +#include <linux/delay.h>
> +#include <linux/ndctl.h>
> +#include <linux/eventfd.h>
> +#include <linux/fs.h>
> +#include <linux/mm_types.h>
> +#include <linux/memory_hotplug.h>
> +#include "ocxl-scm_internal.h"
> +
> +
> +static const struct pci_device_id scm_pci_tbl[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0625), },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(pci, scm_pci_tbl);
> +
> +#define SCM_NUM_MINORS 256 // Total to reserve
> +#define SCM_USABLE_TIMEOUT 120 // seconds
> +
> +static dev_t scm_dev;
> +static struct class *scm_class;
> +static struct mutex minors_idr_lock;
> +static struct idr minors_idr;
> +
> +static const struct attribute_group *scm_pmem_attribute_groups[] = {
> +	&nvdimm_bus_attribute_group,
> +	NULL,
> +};
> +
> +static const struct attribute_group *scm_pmem_region_attribute_groups[] = {
> +	&nd_region_attribute_group,
> +	&nd_device_attribute_group,
> +	&nd_mapping_attribute_group,
> +	&nd_numa_attribute_group,
> +	NULL,
> +};
> +

There is another patch series that is moving this from device driver to
nvdimm core. 

https://lore.kernel.org/linux-mm/[email-masked]

> +/**
> + * scm_ndctl_config_write() - Handle a ND_CMD_SET_CONFIG_DATA command from ndctl
> + * @scm_data: the SCM metadata
> + * @command: the incoming data to write
> + * Return: 0 on success, negative on failure
> + */
> +static int scm_ndctl_config_write(struct scm_data *scm_data,
> +				  struct nd_cmd_set_config_hdr *command)
> +{
> +	if (command->in_offset + command->in_length > SCM_LABEL_AREA_SIZE)
> +		return -EINVAL;
> +
> +	memcpy_flushcache(scm_data->metadata_addr + command->in_offset, command->in_buf,
> +			  command->in_length);
> +
> +	return 0;
> +}
> +
> +/**
> + * scm_ndctl_config_read() - Handle a ND_CMD_GET_CONFIG_DATA command from ndctl
> + * @scm_data: the SCM metadata
> + * @command: the read request
> + * Return: 0 on success, negative on failure
> + */
> +static int scm_ndctl_config_read(struct scm_data *scm_data,
> +				 struct nd_cmd_get_config_data_hdr *command)
> +{
> +	if (command->in_offset + command->in_length > SCM_LABEL_AREA_SIZE)
> +		return -EINVAL;
> +
> +	memcpy(command->out_buf, scm_data->metadata_addr + command->in_offset,
> +	       command->in_length);
> +

memcpy_mcsafe()?

> +	return 0;
> +}
> +
> +/**
> + * scm_ndctl_config_size() - Handle a ND_CMD_GET_CONFIG_SIZE command from ndctl
> + * @scm_data: the SCM metadata
> + * @command: the read request
> + * Return: 0 on success, negative on failure
> + */
> +static int scm_ndctl_config_size(struct nd_cmd_get_config_size *command)
> +{
> +	command->status = 0;
> +	command->config_size = SCM_LABEL_AREA_SIZE;
> +	command->max_xfer = PAGE_SIZE;
> +
> +	return 0;
> +}
> +
> +static int read_smart_attrib(struct scm_data *scm_data, u16 offset,
> +			     struct scm_smart_attribs *attribs)
> +{
> +	u64 val;
> +	int rc;
> +	struct scm_smart_attrib *attrib;
> +	u8 attrib_id;
> +
> +	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, offset, OCXL_LITTLE_ENDIAN,
> +				     &val);
> +	if (rc)
> +		return rc;
> +
> +	attrib_id = (val >> 56) & 0xff;
> +	switch (attrib_id) {
> +	case SCM_SMART_ATTR_POWER_ON_HOURS:
> +		attrib = &attribs->power_on_hours;
> +		break;
> +
> +	case SCM_SMART_ATTR_TEMPERATURE:
> +		attrib = &attribs->temperature;
> +		break;
> +
> +	case SCM_SMART_ATTR_LIFE_REMAINING:
> +		attrib = &attribs->life_remaining;
> +		break;
> +
> +	default:
> +		dev_err(&scm_data->dev, "Unknown smart attrib '%d'", attrib_id);
> +		return -EFAULT;
> +	}
> +
> +	attrib->id = attrib_id;
> +	attrib->attribute_flags = (val >> 40) & 0xffff;
> +	attrib->current_val = (val >> 32) & 0xff;
> +	attrib->threshold_val = (val >> 24) & 0xff;
> +	attrib->worst_val = (val >> 16) & 0xff;
> +
> +	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, offset + 0x08,
> +				     OCXL_LITTLE_ENDIAN, &val);
> +	if (rc)
> +		return rc;
> +
> +	attrib->raw_val = val;
> +
> +	return 0;
> +}
> +
> +static int scm_smart_offset_0x00(struct scm_data *scm_data, u32 *length)
> +'

What is special about _0x00? 

{
> +	int rc;
> +	u64 val;
> +
> +	u16 data_identifier;
> +	u32 data_length;
> +
> +	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
> +				     scm_data->admin_command.data_offset,
> +				     OCXL_LITTLE_ENDIAN, &val);
> +	if (rc)
> +		return rc;
> +
> +	data_identifier = val >> 48;
> +	data_length = val & 0xFFFFFFFF;
> +
> +	if (data_identifier != 0x534D) {
> +		dev_err(&scm_data->dev,
> +			"Bad data identifier for smart data, expected 'SM', got '%-.*s'\n",
> +			2, (char *)&data_identifier);
> +		return -EFAULT;
> +	}
> +
> +	*length = data_length;
> +	return 0;
> +}
> +
> +static int scm_smart_update(struct scm_data *scm_data)
> +{
> +	u32 length, i;
> +	int rc;
> +
> +	mutex_lock(&scm_data->admin_command.lock);
> +
> +	rc = scm_admin_command_request(scm_data, ADMIN_COMMAND_SMART);
> +	if (rc)
> +		goto out;
> +
> +	rc = scm_admin_command_execute(scm_data);
> +	if (rc)
> +		goto out;
> +
> +	rc = scm_admin_command_complete_timeout(scm_data, ADMIN_COMMAND_SMART);
> +	if (rc < 0) {
> +		dev_err(&scm_data->dev, "SMART timeout\n");
> +		goto out;
> +	}
> +
> +	rc = scm_admin_response(scm_data);
> +	if (rc < 0)
> +		goto out;
> +	if (rc != STATUS_SUCCESS) {
> +		scm_warn_status(scm_data, "Unexpected status from SMART", rc);
> +		goto out;
> +	}
> +
> +	rc = scm_smart_offset_0x00(scm_data, &length);
> +	if (rc)
> +		goto out;
> +
> +	length /= 0x10; // Length now contains the number of attributes
> +
> +	for (i = 0; i < length; i++)
> +		read_smart_attrib(scm_data,
> +				  scm_data->admin_command.data_offset + 0x08 + i * 0x10,
> +				  &scm_data->smart);
> +
> +	rc = scm_admin_response_handled(scm_data);
> +	if (rc)
> +		goto out;
> +
> +	rc = 0;
> +	goto out;
> +
> +out:
> +	mutex_unlock(&scm_data->admin_command.lock);
> +	return rc;
> +}
> +
> +static int scm_ndctl_smart(struct scm_data *scm_data, void *buf,
> +			   unsigned int buf_len)
> +{
> +	int rc;
> +
> +	if (buf_len != sizeof(scm_data->smart))
> +		return -EINVAL;
> +
> +	rc = scm_smart_update(scm_data);
> +	if (rc)
> +		return rc;
> +
> +	memcpy(buf, &scm_data->smart, buf_len);
> +
> +	return 0;
> +}
> +
> +
> +static int scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
> +		     struct nvdimm *nvdimm,
> +		     unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
> +{
> +	struct scm_data *scm_data = container_of(nd_desc, struct scm_data, bus_desc);
> +
> +	switch (cmd) {
> +	case ND_CMD_SMART:
> +		*cmd_rc = scm_ndctl_smart(scm_data, buf, buf_len);
> +		return 0;
> +
> +	case ND_CMD_GET_CONFIG_SIZE:
> +		*cmd_rc = scm_ndctl_config_size(buf);
> +		return 0;
> +
> +	case ND_CMD_GET_CONFIG_DATA:
> +		*cmd_rc = scm_ndctl_config_read(scm_data, buf);
> +		return 0;
> +
> +	case ND_CMD_SET_CONFIG_DATA:
> +		*cmd_rc = scm_ndctl_config_write(scm_data, buf);
> +		return 0;
> +
> +	default:
> +		return -ENOTTY;
> +	}
> +}
> +
> +static ssize_t serial_show(struct device *dev,
> +			   struct device_attribute *attr, char *buf)
> +{
> +	struct nvdimm *nvdimm = to_nvdimm(dev);
> +	struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> +	const struct ocxl_fn_config *config = ocxl_function_config(scm_data->ocxl_fn);
> +
> +	return sprintf(buf, "0x%llx\n", config->serial);
> +}
> +static DEVICE_ATTR_RO(serial);
> +
> +static struct attribute *scm_dimm_attributes[] = {
> +	&dev_attr_serial.attr,
> +	NULL,
> +};
> +
> +static umode_t scm_dimm_attr_visible(struct kobject *kobj,
> +				     struct attribute *a, int n)
> +{
> +	return a->mode;
> +}
> +
> +static const struct attribute_group scm_dimm_attribute_group = {
> +	.name = "scm",
> +	.attrs = scm_dimm_attributes,
> +	.is_visible = scm_dimm_attr_visible,
> +};
> +

That is a generic name for dimm attribute

> +static const struct attribute_group *scm_dimm_attribute_groups[] = {
> +	&nvdimm_attribute_group,
> +	&nd_device_attribute_group,
> +	&scm_dimm_attribute_group,
> +	NULL,
> +};
> +
> +/**
> + * scm_reserve_metadata() - Reserve space for nvdimm metadata
> + * @scm_data: The SCM device data
> + * @lpc_mem: The resource representing the LPC memory of the SCM device
> + */
> +static int scm_reserve_metadata(struct scm_data *scm_data,
> +				struct resource *lpc_mem)
> +{
> +	scm_data->metadata_addr = devm_memremap(&scm_data->dev, lpc_mem->start,
> +						SCM_LABEL_AREA_SIZE, MEMREMAP_WB);
> +	if (IS_ERR(scm_data->metadata_addr))
> +		return PTR_ERR(scm_data->metadata_addr);
> +
> +	return 0;
> +}
> +
> +/**
> + * scm_overwrite() - Overwrite all data on the card
> + * @scm_data: The SCM device data
> + * Return: 0 on success
> + */
> +int scm_overwrite(struct scm_data *scm_data)
> +{
> +	int rc;
> +
> +	mutex_lock(&scm_data->ns_command.lock);
> +
> +	rc = scm_ns_command_request(scm_data, NS_COMMAND_SECURE_ERASE);
> +	if (rc)
> +		goto out;
> +
> +	rc = scm_ns_command_execute(scm_data);
> +	if (rc)
> +		goto out;
> +
> +	scm_data->overwrite_state = SCM_OVERWRITE_BUSY;
> +
> +	return 0;
> +
> +out:
> +	mutex_unlock(&scm_data->ns_command.lock);
> +	return rc;
> +}
> +
> +/**
> + * scm_secop_overwrite() - Overwrite all data on the card
> + * @nvdimm: The nvdimm representation of the SCM device to start the overwrite on
> + * @key_data: Unused (no security key implementation)
> + * Return: 0 on success
> + */
> +static int scm_secop_overwrite(struct nvdimm *nvdimm,
> +			       const struct nvdimm_key_data *key_data)
> +{
> +	struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> +
> +	return scm_overwrite(scm_data);
> +}
> +
> +/**
> + * scm_secop_query_overwrite() - Get the current overwrite state
> + * @nvdimm: The nvdimm representation of the SCM device to start the overwrite on
> + * Return: 0 if successful or idle, -EBUSY if busy, -EFAULT if failed
> + */
> +static int scm_secop_query_overwrite(struct nvdimm *nvdimm)
> +{
> +	struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> +
> +	if (scm_data->overwrite_state == SCM_OVERWRITE_BUSY)
> +		return -EBUSY;
> +
> +	if (scm_data->overwrite_state == SCM_OVERWRITE_FAILED)
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +/**
> + * scm_secop_get_flags() - return the security flags for the SCM device
> + */
> +static unsigned long scm_secop_get_flags(struct nvdimm *nvdimm,
> +		enum nvdimm_passphrase_type ptype)
> +{
> +	struct scm_data *scm_data = nvdimm_provider_data(nvdimm);
> +
> +	if (scm_data->overwrite_state == SCM_OVERWRITE_BUSY)
> +		return BIT(NVDIMM_SECURITY_OVERWRITE);
> +
> +	return BIT(NVDIMM_SECURITY_DISABLED);
> +}
> +
> +static const struct nvdimm_security_ops sec_ops  = {
> +	.get_flags = scm_secop_get_flags,
> +	.overwrite = scm_secop_overwrite,
> +	.query_overwrite = scm_secop_query_overwrite,
> +};
> +
> +/**
> + * scm_register_lpc_mem() - Discover persistent memory on a device and register it with the NVDIMM subsystem
> + * @scm_data: The SCM device data
> + * Return: 0 on success
> + */
> +static int scm_register_lpc_mem(struct scm_data *scm_data)
> +{
> +	struct nd_region_desc region_desc;
> +	struct nd_mapping_desc nd_mapping_desc;
> +	struct resource *lpc_mem;
> +	const struct ocxl_afu_config *config;
> +	const struct ocxl_fn_config *fn_config;
> +	int rc;
> +	unsigned long nvdimm_cmd_mask = 0;
> +	unsigned long nvdimm_flags = 0;
> +	int target_node;
> +	char serial[16+1];
> +
> +	// Set up the reserved metadata area
> +	rc = ocxl_afu_map_lpc_mem(scm_data->ocxl_afu);
> +	if (rc < 0)
> +		return rc;
> +
> +	lpc_mem = ocxl_afu_lpc_mem(scm_data->ocxl_afu);
> +	if (lpc_mem == NULL)
> +		return -EINVAL;
> +
> +	config = ocxl_afu_config(scm_data->ocxl_afu);
> +	fn_config = ocxl_function_config(scm_data->ocxl_fn);
> +
> +	rc = scm_reserve_metadata(scm_data, lpc_mem);
> +	if (rc)
> +		return rc;
> +
> +	scm_data->bus_desc.attr_groups = scm_pmem_attribute_groups;
> +	scm_data->bus_desc.provider_name = "scm";
> +	scm_data->bus_desc.ndctl = scm_ndctl;
> +	scm_data->bus_desc.module = THIS_MODULE;
> +
> +	scm_data->nvdimm_bus = nvdimm_bus_register(&scm_data->dev,
> +			       &scm_data->bus_desc);
> +	if (!scm_data->nvdimm_bus)
> +		return -EINVAL;
> +
> +	scm_data->scm_res.start = (u64)lpc_mem->start + SCM_LABEL_AREA_SIZE;
> +	scm_data->scm_res.end = (u64)lpc_mem->start + config->lpc_mem_size - 1;
> +	scm_data->scm_res.name = "SCM persistent memory";
> +
> +	set_bit(ND_CMD_GET_CONFIG_SIZE, &nvdimm_cmd_mask);
> +	set_bit(ND_CMD_GET_CONFIG_DATA, &nvdimm_cmd_mask);
> +	set_bit(ND_CMD_SET_CONFIG_DATA, &nvdimm_cmd_mask);
> +	set_bit(ND_CMD_SMART, &nvdimm_cmd_mask);
> +
> +	set_bit(NDD_ALIASING, &nvdimm_flags);
> +
> +	snprintf(serial, sizeof(serial), "%llx", fn_config->serial);
> +	nd_mapping_desc.nvdimm = __nvdimm_create(scm_data->nvdimm_bus, scm_data,
> +				 scm_dimm_attribute_groups,
> +				 nvdimm_flags, nvdimm_cmd_mask,
> +				 0, NULL, serial, &sec_ops);

nvdimm_create()?

> +	if (!nd_mapping_desc.nvdimm)
> +		return -ENOMEM;
> +
> +	if (nvdimm_bus_check_dimm_count(scm_data->nvdimm_bus, 1))
> +		return -EINVAL;
> +
> +	nd_mapping_desc.start = scm_data->scm_res.start;
> +	nd_mapping_desc.size = resource_size(&scm_data->scm_res);
> +	nd_mapping_desc.position = 0;
> +
> +	scm_data->nd_set.cookie1 = fn_config->serial + 1; // allow for empty serial
> +	scm_data->nd_set.cookie2 = fn_config->serial + 1;
> +
> +	target_node = of_node_to_nid(scm_data->pdev->dev.of_node);
> +
> +	memset(&region_desc, 0, sizeof(region_desc));
> +	region_desc.res = &scm_data->scm_res;
> +	region_desc.attr_groups = scm_pmem_region_attribute_groups;
> +	region_desc.numa_node = NUMA_NO_NODE;
> +	region_desc.target_node = target_node;
> +	region_desc.num_mappings = 1;
> +	region_desc.mapping = &nd_mapping_desc;
> +	region_desc.nd_set = &scm_data->nd_set;
> +
> +	set_bit(ND_REGION_PAGEMAP, &region_desc.flags);
> +	/*
> +	 * NB: libnvdimm copies the data from ndr_desc into it's own
> +	 * structures so passing a stack pointer is fine.
> +	 */
> +	scm_data->nd_region = nvdimm_pmem_region_create(scm_data->nvdimm_bus,
> +			      &region_desc);
> +	if (!scm_data->nd_region)
> +		return -EINVAL;
> +
> +	dev_info(&scm_data->dev,
> +		 "Onlining %lluMB of persistent memory\n",
> +		 nd_mapping_desc.size / SZ_1M);
> +
> +	return 0;
> +}
> +

Would it be possible to split the driver such that we add features like
security ops in later patch? Can this patch be a baisc dirver that just get
the nvdimm initialized. Any attribute specific to ocxl can be exported
in follow up patches?

-aneesh