[v5,3/4] powerpc/papr_scm,uapi: Add support for handling PAPR DSM commands
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Message ID 20200331143229.306718-4-vaibhav@linux.ibm.com
State Superseded
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Series
  • powerpc/papr_scm: Add support for reporting nvdimm health
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Commit Message

Vaibhav Jain March 31, 2020, 2:32 p.m. UTC
Implement support for handling PAPR DSM commands in papr_scm
module. We advertise support for ND_CMD_CALL for the dimm command mask
and implement necessary scaffolding in the module to handle ND_CMD_CALL
ioctl and DSM commands that we receive.

The layout of the DSM commands as we expect from libnvdimm/libndctl is
described in newly introduced uapi header 'papr_scm_dsm.h' which
defines a new 'struct nd_papr_scm_cmd_pkg' header. This header is used
to communicate the DSM command via 'nd_pkg_papr_scm->nd_command' and
size of payload that need to be sent/received for servicing the DSM.

The PAPR DSM commands are assigned indexes started from 0x10000 to
prevent them from overlapping ND_CMD_* values and also makes handling
dimm commands in papr_scm_ndctl(). A new function cmd_to_func() is
implemented that reads the args to papr_scm_ndctl() and performs
sanity tests on them. In case of a DSM command being sent via
ND_CMD_CALL a newly introduced function papr_scm_service_dsm() is
called to handle the request.

Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>

---
Changelog:

v4..v5: Fixed a bug in new implementation of papr_scm_ndctl().

v3..v4: Updated papr_scm_ndctl() to delegate DSM command handling to a
	different function papr_scm_service_dsm(). [Aneesh]

v2..v3: Updated the nd_papr_scm_cmd_pkg to use __xx types as its
	exported to the userspace [Aneesh]

v1..v2: New patch in the series.
---
 arch/powerpc/include/uapi/asm/papr_scm_dsm.h | 161 +++++++++++++++++++
 arch/powerpc/platforms/pseries/papr_scm.c    |  97 ++++++++++-
 2 files changed, 252 insertions(+), 6 deletions(-)
 create mode 100644 arch/powerpc/include/uapi/asm/papr_scm_dsm.h

Comments

Aneesh Kumar K.V April 1, 2020, 5:32 a.m. UTC | #1
Vaibhav Jain <vaibhav@linux.ibm.com> writes:

> Implement support for handling PAPR DSM commands in papr_scm
> module. We advertise support for ND_CMD_CALL for the dimm command mask
> and implement necessary scaffolding in the module to handle ND_CMD_CALL
> ioctl and DSM commands that we receive.
>
> The layout of the DSM commands as we expect from libnvdimm/libndctl is
> described in newly introduced uapi header 'papr_scm_dsm.h' which
> defines a new 'struct nd_papr_scm_cmd_pkg' header. This header is used
> to communicate the DSM command via 'nd_pkg_papr_scm->nd_command' and
> size of payload that need to be sent/received for servicing the DSM.
>
> The PAPR DSM commands are assigned indexes started from 0x10000 to
> prevent them from overlapping ND_CMD_* values and also makes handling
> dimm commands in papr_scm_ndctl(). A new function cmd_to_func() is
> implemented that reads the args to papr_scm_ndctl() and performs
> sanity tests on them. In case of a DSM command being sent via
> ND_CMD_CALL a newly introduced function papr_scm_service_dsm() is
> called to handle the request.
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
>
> ---
> Changelog:
>
> v4..v5: Fixed a bug in new implementation of papr_scm_ndctl().
>
> v3..v4: Updated papr_scm_ndctl() to delegate DSM command handling to a
> 	different function papr_scm_service_dsm(). [Aneesh]
>
> v2..v3: Updated the nd_papr_scm_cmd_pkg to use __xx types as its
> 	exported to the userspace [Aneesh]
>
> v1..v2: New patch in the series.
> ---
>  arch/powerpc/include/uapi/asm/papr_scm_dsm.h | 161 +++++++++++++++++++
>  arch/powerpc/platforms/pseries/papr_scm.c    |  97 ++++++++++-
>  2 files changed, 252 insertions(+), 6 deletions(-)
>  create mode 100644 arch/powerpc/include/uapi/asm/papr_scm_dsm.h
>
> diff --git a/arch/powerpc/include/uapi/asm/papr_scm_dsm.h b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
> new file mode 100644
> index 000000000000..c039a49b41b4
> --- /dev/null
> +++ b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
> @@ -0,0 +1,161 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/*
> + * PAPR SCM Device specific methods and struct for libndctl and ndctl
> + *
> + * (C) Copyright IBM 2020
> + *
> + * Author: Vaibhav Jain <vaibhav at linux.ibm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2, or (at your option)
> + * any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
> +#define _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
> +
> +#include <linux/types.h>
> +
> +#ifdef __KERNEL__
> +#include <linux/ndctl.h>
> +#else
> +#include <ndctl.h>
> +#endif
> +
> +/*
> + * DSM Envelope:
> + *
> + * The ioctl ND_CMD_CALL transfers data between user-space and kernel via
> + * 'envelopes' which consists of a header and user-defined payload sections.
> + * The header is described by 'struct nd_papr_scm_cmd_pkg' which expects a
> + * payload following it and offset of which relative to the struct is provided
> + * by 'nd_papr_scm_cmd_pkg.payload_offset'. *
> + *
> + *  +-------------+---------------------+---------------------------+
> + *  |   64-Bytes  |       8-Bytes       |       Max 184-Bytes       |
> + *  +-------------+---------------------+---------------------------+
> + *  |               nd_papr_scm_cmd_pkg |                           |
> + *  |-------------+                     |                           |
> + *  |  nd_cmd_pkg |                     |                           |
> + *  +-------------+---------------------+---------------------------+
> + *  | nd_family   |			|			    |
> + *  | nd_size_out | cmd_status          |			    |
> + *  | nd_size_in  | payload_version     |      PAYLOAD		    |
> + *  | nd_command  | payload_offset ----->			    |
> + *  | nd_fw_size  |                     |			    |
> + *  +-------------+---------------------+---------------------------+
> + *
> + * DSM Header:
> + *
> + * The header is defined as 'struct nd_papr_scm_cmd_pkg' which embeds a
> + * 'struct nd_cmd_pkg' instance. The DSM command is assigned to member
> + * 'nd_cmd_pkg.nd_command'. Apart from size information of the envelop which is
> + * contained in 'struct nd_cmd_pkg', the header also has members following
> + * members:
> + *
> + * 'cmd_status'		: (Out) Errors if any encountered while servicing DSM.
> + * 'payload_version'	: (In/Out) Version number associated with the payload.
> + * 'payload_offset'	: (In)Relative offset of payload from start of envelope.
> + *
> + * DSM Payload:
> + *
> + * The layout of the DSM Payload is defined by various structs shared between
> + * papr_scm and libndctl so that contents of payload can be interpreted. During
> + * servicing of a DSM the papr_scm module will read input args from the payload
> + * field by casting its contents to an appropriate struct pointer based on the
> + * DSM command. Similarly the output of servicing the DSM command will be copied
> + * to the payload field using the same struct.
> + *
> + * 'libnvdimm' enforces a hard limit of 256 bytes on the envelope size, which
> + * leaves around 184 bytes for the envelope payload (ignoring any padding that
> + * the compiler may silently introduce).
> + *
> + * Payload Version:
> + *
> + * A 'payload_version' field is present in DSM header that indicates a specific
> + * version of the structure present in DSM Payload for a given DSM command. This
> + * provides backward compatibility in case the DSM Payload structure evolves
> + * and different structures are supported by 'papr_scm' and 'libndctl'.
> + *
> + * When sending a DSM Payload to 'papr_scm', 'libndctl' should send the version
> + * of the payload struct it supports via 'payload_version' field. The 'papr_scm'
> + * module when servicing the DSM envelop checks the 'payload_version' and then
> + * uses 'payload struct version' == MIN('payload_version field',
> + * 'max payload-struct-version supported by papr_scm') to service the DSM. After
> + * servicing the DSM, 'papr_scm' put the negotiated version of payload struct in
> + * returned 'payload_version' field.
> + *
> + * Libndctl on receiving the envelop back from papr_scm again checks the
> + * 'payload_version' field and based on it use the appropriate version dsm
> + * struct to parse the results.
> + *
> + * Backward Compatibility:
> + *
> + * Above scheme of exchanging different versioned DSM struct between libndctl
> + * and papr_scm should provide backward compatibility until following two
> + * assumptions/conditions when defining new DSM structs hold:
> + *
> + * Let T(X) = { set of attributes in DSM struct 'T' versioned X }
> + *
> + * 1. T(X) is a proper subset of T(Y) if X > Y.
> + *    i.e Each new version of DSM struct should retain existing struct
> + *    attributes from previous version
> + *
> + * 2. If an entity (libndctl or papr_scm) supports a DSM struct T(X) then
> + *    it should also support T(1), T(2)...T(X - 1).
> + *    i.e When adding support for new version of a DSM struct, libndctl
> + *    and papr_scm should retain support of the existing DSM struct
> + *    version they support.
> + */
> +
> +/* Papr-scm-header + payload expected with ND_CMD_CALL ioctl from libnvdimm */
> +struct nd_papr_scm_cmd_pkg {
> +	struct nd_cmd_pkg hdr;		/* Package header containing sub-cmd */
> +	__s32 cmd_status;		/* Out: Sub-cmd status returned back */
> +	__u16 payload_offset;	/* In: offset from start of struct */
> +	__u16 payload_version;	/* In/Out: version of the payload */
> +	__u8 payload[];		/* In/Out: Sub-cmd data buffer */
> +};
> +
> +/*
> + * Sub commands for ND_CMD_CALL. To prevent overlap from ND_CMD_*, values for
> + * these enums start at 0x10000. These values are then returned from
> + * cmd_to_func() making it easy to implement the switch-case block in
> + * papr_scm_ndctl(). These commands are sent to the kernel via
> + * 'nd_papr_scm_cmd_pkg.hdr.nd_command'
> + */
> +enum dsm_papr_scm {
> +	DSM_PAPR_SCM_MIN =  0x10000,
> +	DSM_PAPR_SCM_MAX,
> +};
> +
> +/* Helpers to evaluate the size of PAPR_SCM envelope */
> +/* Calculate the papr_scm-header size */
> +#define ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE \
> +	(sizeof(struct nd_papr_scm_cmd_pkg) - sizeof(struct nd_cmd_pkg))
> +
> +/* Given a type calculate envelope-content size (papr_scm-header + payload) */
> +#define ND_PAPR_SCM_ENVELOPE_CONTENT_SIZE(_type_)	\
> +	(sizeof(_type_) + ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE)
> +
> +/* Convert a libnvdimm nd_cmd_pkg to papr_scm specific pkg */
> +static struct nd_papr_scm_cmd_pkg *nd_to_papr_cmd_pkg(struct nd_cmd_pkg *cmd)
> +{
> +	return (struct nd_papr_scm_cmd_pkg *) cmd;
> +}
> +
> +/* Return the payload pointer for a given pcmd */
> +static void *papr_scm_pcmd_to_payload(struct nd_papr_scm_cmd_pkg *pcmd)
> +{
> +	if (pcmd->hdr.nd_size_in == 0 && pcmd->hdr.nd_size_out == 0)
> +		return NULL;
> +	else
> +		return (void *)((__u8 *) pcmd + pcmd->payload_offset);
> +}
> +#endif /* _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_ */
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index aaf2e4ab1f75..e8ce96d2249e 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -15,13 +15,15 @@
>  
>  #include <asm/plpar_wrappers.h>
>  #include <asm/papr_scm.h>
> +#include <asm/papr_scm_dsm.h>
>  
>  #define BIND_ANY_ADDR (~0ul)
>  
>  #define PAPR_SCM_DIMM_CMD_MASK \
>  	((1ul << ND_CMD_GET_CONFIG_SIZE) | \
>  	 (1ul << ND_CMD_GET_CONFIG_DATA) | \
> -	 (1ul << ND_CMD_SET_CONFIG_DATA))
> +	 (1ul << ND_CMD_SET_CONFIG_DATA) | \
> +	 (1ul << ND_CMD_CALL))
>  
>  struct papr_scm_priv {
>  	struct platform_device *pdev;
> @@ -283,15 +285,92 @@ static int papr_scm_meta_set(struct papr_scm_priv *p,
>  	return 0;
>  }
>  
> +/*
> + * Validate the inputs args to dimm-control function and return '0' if valid.
> + * This also does initial sanity validation to ND_CMD_CALL sub-command packages.
> + */
> +static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
> +		       unsigned int buf_len)
> +{
> +	unsigned long cmd_mask = PAPR_SCM_DIMM_CMD_MASK;
> +	struct nd_papr_scm_cmd_pkg *pkg = nd_to_papr_cmd_pkg(buf);
> +
> +	/* Only dimm-specific calls are supported atm */
> +	if (!nvdimm)
> +		return -EINVAL;
> +
> +	if (!test_bit(cmd, &cmd_mask)) {
> +		pr_debug("%s: Unsupported cmd=%u\n", __func__, cmd);
> +		return -EINVAL;
> +	} else if (cmd == ND_CMD_CALL) {
> +
> +		/* Verify the envelop package */
> +		if (!buf || buf_len < sizeof(struct nd_papr_scm_cmd_pkg)) {
> +			pr_debug("%s: Invalid pkg size=%u\n", __func__,
> +				 buf_len);
> +			return -EINVAL;
> +		}
> +
> +		/* Verify that the DSM command family is valid */
> +		if (pkg->hdr.nd_family != NVDIMM_FAMILY_PAPR_SCM) {
> +			pr_debug("%s: Invalid pkg family=0x%llx\n", __func__,
> +				 pkg->hdr.nd_family);
> +			return -EINVAL;
> +
> +		}
> +
> +		/* We except a payload with all DSM commands */
> +		if (papr_scm_pcmd_to_payload(pkg) == NULL) {
> +			pr_debug("%s: Empty payload for sub-command=0x%llx\n",
> +				 __func__, pkg->hdr.nd_command);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	/* Command looks valid */
> +	return 0;
> +}
> +
> +static int papr_scm_service_dsm(struct papr_scm_priv *p,
> +				struct nd_papr_scm_cmd_pkg *call_pkg)
> +{
> +	/* unknown subcommands return error in packages */
> +	if (call_pkg->hdr.nd_command <= DSM_PAPR_SCM_MIN ||
> +	    call_pkg->hdr.nd_command >= DSM_PAPR_SCM_MAX) {
> +		pr_debug("Invalid DSM command 0x%llx\n",
> +			 call_pkg->hdr.nd_command);
> +		call_pkg->cmd_status = -EINVAL;
> +		return 0;
> +	}
> +
> +	/* Depending on the DSM command call appropriate service routine */
> +	switch (call_pkg->hdr.nd_command) {
> +	default:
> +		pr_debug("Unsupported DSM command 0x%llx\n",
> +			 call_pkg->hdr.nd_command);
> +		call_pkg->cmd_status = -ENOENT;
> +		return 0;
> +	}
> +}
> +
>  int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
>  		unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
>  {
>  	struct nd_cmd_get_config_size *get_size_hdr;
>  	struct papr_scm_priv *p;
> +	struct nd_papr_scm_cmd_pkg *call_pkg = NULL;
> +	int rc;
>  
> -	/* Only dimm-specific calls are supported atm */
> -	if (!nvdimm)
> -		return -EINVAL;
> +	/* Use a local variable in case cmd_rc pointer is NULL */
> +	if (cmd_rc == NULL)
> +		cmd_rc = &rc;
> +
> +	*cmd_rc = is_cmd_valid(nvdimm, cmd, buf, buf_len);
> +	if (*cmd_rc) {
> +		pr_debug("%s: Invalid cmd=0x%x. Err=%d\n", __func__,
> +			 cmd, *cmd_rc);
> +		return *cmd_rc;
> +	}
>  
>  	p = nvdimm_provider_data(nvdimm);
>  
> @@ -313,13 +392,19 @@ int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
>  		*cmd_rc = papr_scm_meta_set(p, buf);
>  		break;
>  
> +	case ND_CMD_CALL:
> +		call_pkg = nd_to_papr_cmd_pkg(buf);
> +		*cmd_rc = papr_scm_service_dsm(p, call_pkg);
> +		break;
> +
>  	default:
> -		return -EINVAL;
> +		dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
> +		*cmd_rc = -EINVAL;
>  	}
>  
>  	dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
>  
> -	return 0;
> +	return *cmd_rc;
>  }
>  
>  static inline int papr_scm_node(int node)
> -- 
> 2.25.1
> _______________________________________________
> Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
> To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
Dan Williams April 3, 2020, 5:40 p.m. UTC | #2
On Tue, Mar 31, 2020 at 7:33 AM Vaibhav Jain <vaibhav@linux.ibm.com> wrote:
>
> Implement support for handling PAPR DSM commands in papr_scm
> module. We advertise support for ND_CMD_CALL for the dimm command mask
> and implement necessary scaffolding in the module to handle ND_CMD_CALL
> ioctl and DSM commands that we receive.

They aren't ACPI Device Specific Methods in the papr_scm case, right?
I'd call them what the papr_scm specification calls them and replace
"DSM" throughout.

> The layout of the DSM commands as we expect from libnvdimm/libndctl is
> described in newly introduced uapi header 'papr_scm_dsm.h' which
> defines a new 'struct nd_papr_scm_cmd_pkg' header. This header is used
> to communicate the DSM command via 'nd_pkg_papr_scm->nd_command' and
> size of payload that need to be sent/received for servicing the DSM.
>
> The PAPR DSM commands are assigned indexes started from 0x10000 to
> prevent them from overlapping ND_CMD_* values and also makes handling
> dimm commands in papr_scm_ndctl().

You don't necessarily need to have command number separation like
that. The function number spaces are unique per family.

> A new function cmd_to_func() is
> implemented that reads the args to papr_scm_ndctl() and performs
> sanity tests on them. In case of a DSM command being sent via
> ND_CMD_CALL a newly introduced function papr_scm_service_dsm() is
> called to handle the request.
>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
>
> ---
> Changelog:
>
> v4..v5: Fixed a bug in new implementation of papr_scm_ndctl().
>
> v3..v4: Updated papr_scm_ndctl() to delegate DSM command handling to a
>         different function papr_scm_service_dsm(). [Aneesh]
>
> v2..v3: Updated the nd_papr_scm_cmd_pkg to use __xx types as its
>         exported to the userspace [Aneesh]
>
> v1..v2: New patch in the series.
> ---
>  arch/powerpc/include/uapi/asm/papr_scm_dsm.h | 161 +++++++++++++++++++
>  arch/powerpc/platforms/pseries/papr_scm.c    |  97 ++++++++++-
>  2 files changed, 252 insertions(+), 6 deletions(-)
>  create mode 100644 arch/powerpc/include/uapi/asm/papr_scm_dsm.h
>
> diff --git a/arch/powerpc/include/uapi/asm/papr_scm_dsm.h b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
> new file mode 100644
> index 000000000000..c039a49b41b4
> --- /dev/null
> +++ b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
> @@ -0,0 +1,161 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/*
> + * PAPR SCM Device specific methods and struct for libndctl and ndctl
> + *
> + * (C) Copyright IBM 2020
> + *
> + * Author: Vaibhav Jain <vaibhav at linux.ibm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2, or (at your option)
> + * any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.

These 2 paragraphs of redundant license text can be dropped. The SPDX
line is sufficient.

> + */
> +
> +#ifndef _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
> +#define _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
> +
> +#include <linux/types.h>
> +
> +#ifdef __KERNEL__
> +#include <linux/ndctl.h>
> +#else
> +#include <ndctl.h>
> +#endif
> +
> +/*
> + * DSM Envelope:
> + *
> + * The ioctl ND_CMD_CALL transfers data between user-space and kernel via
> + * 'envelopes' which consists of a header and user-defined payload sections.
> + * The header is described by 'struct nd_papr_scm_cmd_pkg' which expects a
> + * payload following it and offset of which relative to the struct is provided
> + * by 'nd_papr_scm_cmd_pkg.payload_offset'. *
> + *
> + *  +-------------+---------------------+---------------------------+
> + *  |   64-Bytes  |       8-Bytes       |       Max 184-Bytes       |
> + *  +-------------+---------------------+---------------------------+
> + *  |               nd_papr_scm_cmd_pkg |                           |
> + *  |-------------+                     |                           |
> + *  |  nd_cmd_pkg |                     |                           |
> + *  +-------------+---------------------+---------------------------+
> + *  | nd_family   |                    |                           |
> + *  | nd_size_out | cmd_status          |                          |
> + *  | nd_size_in  | payload_version     |      PAYLOAD             |
> + *  | nd_command  | payload_offset ----->                          |
> + *  | nd_fw_size  |                     |                          |
> + *  +-------------+---------------------+---------------------------+
> + *
> + * DSM Header:
> + *
> + * The header is defined as 'struct nd_papr_scm_cmd_pkg' which embeds a
> + * 'struct nd_cmd_pkg' instance. The DSM command is assigned to member
> + * 'nd_cmd_pkg.nd_command'. Apart from size information of the envelop which is

 s/envelop/envelope/

There's a difference between commands and functions in libnvdimm.
Commands are the top-level ioctl methods where ND_CMD_CALL is the
generic payload command and functions are communicated inside of that
wrapper. Otherwise if the command does not wrap other commands like
ND_CMD_{GET,SET}_CONFIG_DATA then the individual bus providers
translate them to the bus-local functionality. For example
ND_CMD_{GET,SET}_CONFIG_DATA correspond to either the _LSx ACPI
methods, or the Intel DSM label methods. The details of those
implementations are hidden from the caller, the caller just sees the
kernel's ND_CMD_{GET,SET}_CONFIG_DATA interface.

> + * contained in 'struct nd_cmd_pkg', the header also has members following
> + * members:
> + *
> + * 'cmd_status'                : (Out) Errors if any encountered while servicing DSM.
> + * 'payload_version'   : (In/Out) Version number associated with the payload.
> + * 'payload_offset'    : (In)Relative offset of payload from start of envelope.
> + *
> + * DSM Payload:
> + *
> + * The layout of the DSM Payload is defined by various structs shared between
> + * papr_scm and libndctl so that contents of payload can be interpreted. During
> + * servicing of a DSM the papr_scm module will read input args from the payload
> + * field by casting its contents to an appropriate struct pointer based on the
> + * DSM command. Similarly the output of servicing the DSM command will be copied
> + * to the payload field using the same struct.
> + *
> + * 'libnvdimm' enforces a hard limit of 256 bytes on the envelope size, which
> + * leaves around 184 bytes for the envelope payload (ignoring any padding that
> + * the compiler may silently introduce).
> + *
> + * Payload Version:
> + *
> + * A 'payload_version' field is present in DSM header that indicates a specific
> + * version of the structure present in DSM Payload for a given DSM command. This
> + * provides backward compatibility in case the DSM Payload structure evolves
> + * and different structures are supported by 'papr_scm' and 'libndctl'.
> + *
> + * When sending a DSM Payload to 'papr_scm', 'libndctl' should send the version
> + * of the payload struct it supports via 'payload_version' field. The 'papr_scm'
> + * module when servicing the DSM envelop checks the 'payload_version' and then

s/envelop/envelope/

> + * uses 'payload struct version' == MIN('payload_version field',
> + * 'max payload-struct-version supported by papr_scm') to service the DSM. After
> + * servicing the DSM, 'papr_scm' put the negotiated version of payload struct in
> + * returned 'payload_version' field.
> + *
> + * Libndctl on receiving the envelop back from papr_scm again checks the

s/envelop/envelope/

> + * 'payload_version' field and based on it use the appropriate version dsm
> + * struct to parse the results.
> + *
> + * Backward Compatibility:
> + *
> + * Above scheme of exchanging different versioned DSM struct between libndctl
> + * and papr_scm should provide backward compatibility until following two
> + * assumptions/conditions when defining new DSM structs hold:
> + *
> + * Let T(X) = { set of attributes in DSM struct 'T' versioned X }
> + *
> + * 1. T(X) is a proper subset of T(Y) if X > Y.
> + *    i.e Each new version of DSM struct should retain existing struct
> + *    attributes from previous version
> + *
> + * 2. If an entity (libndctl or papr_scm) supports a DSM struct T(X) then
> + *    it should also support T(1), T(2)...T(X - 1).
> + *    i.e When adding support for new version of a DSM struct, libndctl
> + *    and papr_scm should retain support of the existing DSM struct
> + *    version they support.
> + */
> +
> +/* Papr-scm-header + payload expected with ND_CMD_CALL ioctl from libnvdimm */
> +struct nd_papr_scm_cmd_pkg {
> +       struct nd_cmd_pkg hdr;          /* Package header containing sub-cmd */
> +       __s32 cmd_status;               /* Out: Sub-cmd status returned back */
> +       __u16 payload_offset;   /* In: offset from start of struct */
> +       __u16 payload_version;  /* In/Out: version of the payload */
> +       __u8 payload[];         /* In/Out: Sub-cmd data buffer */

Does this structure pack the same on all compilers?

> +};
> +
> +/*
> + * Sub commands for ND_CMD_CALL. To prevent overlap from ND_CMD_*, values for
> + * these enums start at 0x10000. These values are then returned from
> + * cmd_to_func() making it easy to implement the switch-case block in
> + * papr_scm_ndctl(). These commands are sent to the kernel via
> + * 'nd_papr_scm_cmd_pkg.hdr.nd_command'
> + */

With nd_family set to NVDIMM_FAMILY_PAPR_SCM the function number space
can overlap the function numbers from other families.

> +enum dsm_papr_scm {
> +       DSM_PAPR_SCM_MIN =  0x10000,
> +       DSM_PAPR_SCM_MAX,
> +};
> +
> +/* Helpers to evaluate the size of PAPR_SCM envelope */
> +/* Calculate the papr_scm-header size */
> +#define ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE \
> +       (sizeof(struct nd_papr_scm_cmd_pkg) - sizeof(struct nd_cmd_pkg))
> +
> +/* Given a type calculate envelope-content size (papr_scm-header + payload) */
> +#define ND_PAPR_SCM_ENVELOPE_CONTENT_SIZE(_type_)      \
> +       (sizeof(_type_) + ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE)
> +
> +/* Convert a libnvdimm nd_cmd_pkg to papr_scm specific pkg */
> +static struct nd_papr_scm_cmd_pkg *nd_to_papr_cmd_pkg(struct nd_cmd_pkg *cmd)
> +{
> +       return (struct nd_papr_scm_cmd_pkg *) cmd;
> +}
> +
> +/* Return the payload pointer for a given pcmd */
> +static void *papr_scm_pcmd_to_payload(struct nd_papr_scm_cmd_pkg *pcmd)
> +{
> +       if (pcmd->hdr.nd_size_in == 0 && pcmd->hdr.nd_size_out == 0)
> +               return NULL;
> +       else
> +               return (void *)((__u8 *) pcmd + pcmd->payload_offset);
> +}
> +#endif /* _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_ */
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index aaf2e4ab1f75..e8ce96d2249e 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -15,13 +15,15 @@
>
>  #include <asm/plpar_wrappers.h>
>  #include <asm/papr_scm.h>
> +#include <asm/papr_scm_dsm.h>
>
>  #define BIND_ANY_ADDR (~0ul)
>
>  #define PAPR_SCM_DIMM_CMD_MASK \
>         ((1ul << ND_CMD_GET_CONFIG_SIZE) | \
>          (1ul << ND_CMD_GET_CONFIG_DATA) | \
> -        (1ul << ND_CMD_SET_CONFIG_DATA))
> +        (1ul << ND_CMD_SET_CONFIG_DATA) | \
> +        (1ul << ND_CMD_CALL))
>
>  struct papr_scm_priv {
>         struct platform_device *pdev;
> @@ -283,15 +285,92 @@ static int papr_scm_meta_set(struct papr_scm_priv *p,
>         return 0;
>  }
>
> +/*
> + * Validate the inputs args to dimm-control function and return '0' if valid.
> + * This also does initial sanity validation to ND_CMD_CALL sub-command packages.
> + */
> +static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
> +                      unsigned int buf_len)
> +{
> +       unsigned long cmd_mask = PAPR_SCM_DIMM_CMD_MASK;
> +       struct nd_papr_scm_cmd_pkg *pkg = nd_to_papr_cmd_pkg(buf);
> +
> +       /* Only dimm-specific calls are supported atm */
> +       if (!nvdimm)
> +               return -EINVAL;
> +
> +       if (!test_bit(cmd, &cmd_mask)) {
> +               pr_debug("%s: Unsupported cmd=%u\n", __func__, cmd);

Please convert all the pr_debug() statements in this file to
dev_dbg(). Also you don't need to put the __func__ in the print
statement because you can enable that via dynamic_debug_control see
the "f" flag in addition to the "p" flag for dynamic debug enabling.

> +               return -EINVAL;
> +       } else if (cmd == ND_CMD_CALL) {
> +
> +               /* Verify the envelop package */

s/envelop/envelope/

> +               if (!buf || buf_len < sizeof(struct nd_papr_scm_cmd_pkg)) {
> +                       pr_debug("%s: Invalid pkg size=%u\n", __func__,
> +                                buf_len);
> +                       return -EINVAL;
> +               }
> +
> +               /* Verify that the DSM command family is valid */
> +               if (pkg->hdr.nd_family != NVDIMM_FAMILY_PAPR_SCM) {
> +                       pr_debug("%s: Invalid pkg family=0x%llx\n", __func__,
> +                                pkg->hdr.nd_family);
> +                       return -EINVAL;
> +
> +               }
> +
> +               /* We except a payload with all DSM commands */
> +               if (papr_scm_pcmd_to_payload(pkg) == NULL) {
> +                       pr_debug("%s: Empty payload for sub-command=0x%llx\n",
> +                                __func__, pkg->hdr.nd_command);
> +                       return -EINVAL;
> +               }
> +       }
> +
> +       /* Command looks valid */
> +       return 0;
> +}
> +
> +static int papr_scm_service_dsm(struct papr_scm_priv *p,
> +                               struct nd_papr_scm_cmd_pkg *call_pkg)
> +{
> +       /* unknown subcommands return error in packages */
> +       if (call_pkg->hdr.nd_command <= DSM_PAPR_SCM_MIN ||
> +           call_pkg->hdr.nd_command >= DSM_PAPR_SCM_MAX) {
> +               pr_debug("Invalid DSM command 0x%llx\n",
> +                        call_pkg->hdr.nd_command);
> +               call_pkg->cmd_status = -EINVAL;
> +               return 0;
> +       }
> +
> +       /* Depending on the DSM command call appropriate service routine */
> +       switch (call_pkg->hdr.nd_command) {
> +       default:
> +               pr_debug("Unsupported DSM command 0x%llx\n",
> +                        call_pkg->hdr.nd_command);
> +               call_pkg->cmd_status = -ENOENT;
> +               return 0;
> +       }
> +}
> +
>  int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
>                 unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
>  {
>         struct nd_cmd_get_config_size *get_size_hdr;
>         struct papr_scm_priv *p;
> +       struct nd_papr_scm_cmd_pkg *call_pkg = NULL;
> +       int rc;
>
> -       /* Only dimm-specific calls are supported atm */
> -       if (!nvdimm)
> -               return -EINVAL;
> +       /* Use a local variable in case cmd_rc pointer is NULL */
> +       if (cmd_rc == NULL)
> +               cmd_rc = &rc;
> +
> +       *cmd_rc = is_cmd_valid(nvdimm, cmd, buf, buf_len);
> +       if (*cmd_rc) {
> +               pr_debug("%s: Invalid cmd=0x%x. Err=%d\n", __func__,
> +                        cmd, *cmd_rc);
> +               return *cmd_rc;
> +       }
>
>         p = nvdimm_provider_data(nvdimm);
>
> @@ -313,13 +392,19 @@ int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
>                 *cmd_rc = papr_scm_meta_set(p, buf);
>                 break;
>
> +       case ND_CMD_CALL:
> +               call_pkg = nd_to_papr_cmd_pkg(buf);
> +               *cmd_rc = papr_scm_service_dsm(p, call_pkg);
> +               break;
> +
>         default:
> -               return -EINVAL;
> +               dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
> +               *cmd_rc = -EINVAL;
>         }
>
>         dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
>
> -       return 0;
> +       return *cmd_rc;
>  }
>
>  static inline int papr_scm_node(int node)
> --
> 2.25.1
>
Vaibhav Jain April 3, 2020, 8:30 p.m. UTC | #3
Dan Williams <dan.j.williams@intel.com> writes:

> On Tue, Mar 31, 2020 at 7:33 AM Vaibhav Jain <vaibhav@linux.ibm.com> wrote:
>>
>> Implement support for handling PAPR DSM commands in papr_scm
>> module. We advertise support for ND_CMD_CALL for the dimm command mask
>> and implement necessary scaffolding in the module to handle ND_CMD_CALL
>> ioctl and DSM commands that we receive.
>
> They aren't ACPI Device Specific Methods in the papr_scm case, right?
> I'd call them what the papr_scm specification calls them and replace
> "DSM" throughout.
Right, papr_scm doesnt use ACPI. However there is no pre-existing term
for these methods as they are defined by us. Hence we reused the "DSM"
to indicate meaning similar to what ACPI does.

The closest term in papr_scm spec is Hcall thats a system-call to
hypervisor to fetch some data. But there is no 1:1 mapping between HCall
and these "DSMs". 

>
>> The layout of the DSM commands as we expect from libnvdimm/libndctl is
>> described in newly introduced uapi header 'papr_scm_dsm.h' which
>> defines a new 'struct nd_papr_scm_cmd_pkg' header. This header is used
>> to communicate the DSM command via 'nd_pkg_papr_scm->nd_command' and
>> size of payload that need to be sent/received for servicing the DSM.
>>
>> The PAPR DSM commands are assigned indexes started from 0x10000 to
>> prevent them from overlapping ND_CMD_* values and also makes handling
>> dimm commands in papr_scm_ndctl().
>
> You don't necessarily need to have command number separation like
> that. The function number spaces are unique per family.
>
Right. This is a carry over from previous version of this patchset that
tried using ND_CMD_& and PAPR_DSM_* in a single switch-case
block. However not needed anymore, hence I will switch to values
starting from 0x0 in next iteration.

>> A new function cmd_to_func() is
>> implemented that reads the args to papr_scm_ndctl() and performs
>> sanity tests on them. In case of a DSM command being sent via
>> ND_CMD_CALL a newly introduced function papr_scm_service_dsm() is
>> called to handle the request.
>>
>> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
>>
>> ---
>> Changelog:
>>
>> v4..v5: Fixed a bug in new implementation of papr_scm_ndctl().
>>
>> v3..v4: Updated papr_scm_ndctl() to delegate DSM command handling to a
>>         different function papr_scm_service_dsm(). [Aneesh]
>>
>> v2..v3: Updated the nd_papr_scm_cmd_pkg to use __xx types as its
>>         exported to the userspace [Aneesh]
>>
>> v1..v2: New patch in the series.
>> ---
>>  arch/powerpc/include/uapi/asm/papr_scm_dsm.h | 161 +++++++++++++++++++
>>  arch/powerpc/platforms/pseries/papr_scm.c    |  97 ++++++++++-
>>  2 files changed, 252 insertions(+), 6 deletions(-)
>>  create mode 100644 arch/powerpc/include/uapi/asm/papr_scm_dsm.h
>>
>> diff --git a/arch/powerpc/include/uapi/asm/papr_scm_dsm.h b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
>> new file mode 100644
>> index 000000000000..c039a49b41b4
>> --- /dev/null
>> +++ b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
>> @@ -0,0 +1,161 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
>> +/*
>> + * PAPR SCM Device specific methods and struct for libndctl and ndctl
>> + *
>> + * (C) Copyright IBM 2020
>> + *
>> + * Author: Vaibhav Jain <vaibhav at linux.ibm.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2, or (at your option)
>> + * any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>
> These 2 paragraphs of redundant license text can be dropped. The SPDX
> line is sufficient.
Agree, will address this in next iteration.

>
>> + */
>> +
>> +#ifndef _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
>> +#define _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
>> +
>> +#include <linux/types.h>
>> +
>> +#ifdef __KERNEL__
>> +#include <linux/ndctl.h>
>> +#else
>> +#include <ndctl.h>
>> +#endif
>> +
>> +/*
>> + * DSM Envelope:
>> + *
>> + * The ioctl ND_CMD_CALL transfers data between user-space and kernel via
>> + * 'envelopes' which consists of a header and user-defined payload sections.
>> + * The header is described by 'struct nd_papr_scm_cmd_pkg' which expects a
>> + * payload following it and offset of which relative to the struct is provided
>> + * by 'nd_papr_scm_cmd_pkg.payload_offset'. *
>> + *
>> + *  +-------------+---------------------+---------------------------+
>> + *  |   64-Bytes  |       8-Bytes       |       Max 184-Bytes       |
>> + *  +-------------+---------------------+---------------------------+
>> + *  |               nd_papr_scm_cmd_pkg |                           |
>> + *  |-------------+                     |                           |
>> + *  |  nd_cmd_pkg |                     |                           |
>> + *  +-------------+---------------------+---------------------------+
>> + *  | nd_family   |                    |                           |
>> + *  | nd_size_out | cmd_status          |                          |
>> + *  | nd_size_in  | payload_version     |      PAYLOAD             |
>> + *  | nd_command  | payload_offset ----->                          |
>> + *  | nd_fw_size  |                     |                          |
>> + *  +-------------+---------------------+---------------------------+
>> + *
>> + * DSM Header:
>> + *
>> + * The header is defined as 'struct nd_papr_scm_cmd_pkg' which embeds a
>> + * 'struct nd_cmd_pkg' instance. The DSM command is assigned to member
>> + * 'nd_cmd_pkg.nd_command'. Apart from size information of the envelop which is
>
>  s/envelop/envelope/
Agree, will fix this and other instances of the same error

>
> There's a difference between commands and functions in libnvdimm.
> Commands are the top-level ioctl methods where ND_CMD_CALL is the
> generic payload command and functions are communicated inside of that
> wrapper. Otherwise if the command does not wrap other commands like
> ND_CMD_{GET,SET}_CONFIG_DATA then the individual bus providers
> translate them to the bus-local functionality. For example
> ND_CMD_{GET,SET}_CONFIG_DATA correspond to either the _LSx ACPI
> methods, or the Intel DSM label methods. The details of those
> implementations are hidden from the caller, the caller just sees the
> kernel's ND_CMD_{GET,SET}_CONFIG_DATA interface.
>
>> + * contained in 'struct nd_cmd_pkg', the header also has members following
>> + * members:
>> + *
>> + * 'cmd_status'                : (Out) Errors if any encountered while servicing DSM.
>> + * 'payload_version'   : (In/Out) Version number associated with the payload.
>> + * 'payload_offset'    : (In)Relative offset of payload from start of envelope.
>> + *
>> + * DSM Payload:
>> + *
>> + * The layout of the DSM Payload is defined by various structs shared between
>> + * papr_scm and libndctl so that contents of payload can be interpreted. During
>> + * servicing of a DSM the papr_scm module will read input args from the payload
>> + * field by casting its contents to an appropriate struct pointer based on the
>> + * DSM command. Similarly the output of servicing the DSM command will be copied
>> + * to the payload field using the same struct.
>> + *
>> + * 'libnvdimm' enforces a hard limit of 256 bytes on the envelope size, which
>> + * leaves around 184 bytes for the envelope payload (ignoring any padding that
>> + * the compiler may silently introduce).
>> + *
>> + * Payload Version:
>> + *
>> + * A 'payload_version' field is present in DSM header that indicates a specific
>> + * version of the structure present in DSM Payload for a given DSM command. This
>> + * provides backward compatibility in case the DSM Payload structure evolves
>> + * and different structures are supported by 'papr_scm' and 'libndctl'.
>> + *
>> + * When sending a DSM Payload to 'papr_scm', 'libndctl' should send the version
>> + * of the payload struct it supports via 'payload_version' field. The 'papr_scm'
>> + * module when servicing the DSM envelop checks the 'payload_version' and then
>
> s/envelop/envelope/
>
>> + * uses 'payload struct version' == MIN('payload_version field',
>> + * 'max payload-struct-version supported by papr_scm') to service the DSM. After
>> + * servicing the DSM, 'papr_scm' put the negotiated version of payload struct in
>> + * returned 'payload_version' field.
>> + *
>> + * Libndctl on receiving the envelop back from papr_scm again checks the
>
> s/envelop/envelope/
>
>> + * 'payload_version' field and based on it use the appropriate version dsm
>> + * struct to parse the results.
>> + *
>> + * Backward Compatibility:
>> + *
>> + * Above scheme of exchanging different versioned DSM struct between libndctl
>> + * and papr_scm should provide backward compatibility until following two
>> + * assumptions/conditions when defining new DSM structs hold:
>> + *
>> + * Let T(X) = { set of attributes in DSM struct 'T' versioned X }
>> + *
>> + * 1. T(X) is a proper subset of T(Y) if X > Y.
>> + *    i.e Each new version of DSM struct should retain existing struct
>> + *    attributes from previous version
>> + *
>> + * 2. If an entity (libndctl or papr_scm) supports a DSM struct T(X) then
>> + *    it should also support T(1), T(2)...T(X - 1).
>> + *    i.e When adding support for new version of a DSM struct, libndctl
>> + *    and papr_scm should retain support of the existing DSM struct
>> + *    version they support.
>> + */
>> +
>> +/* Papr-scm-header + payload expected with ND_CMD_CALL ioctl from libnvdimm */
>> +struct nd_papr_scm_cmd_pkg {
>> +       struct nd_cmd_pkg hdr;          /* Package header containing sub-cmd */
>> +       __s32 cmd_status;               /* Out: Sub-cmd status returned back */
>> +       __u16 payload_offset;   /* In: offset from start of struct */
>> +       __u16 payload_version;  /* In/Out: version of the payload */
>> +       __u8 payload[];         /* In/Out: Sub-cmd data buffer */
>
> Does this structure pack the same on all compilers?
I tried with both gcc-8.2 and clang-9.0 and pahole reported the same
struct layout. 

>
>> +};
>> +
>> +/*
>> + * Sub commands for ND_CMD_CALL. To prevent overlap from ND_CMD_*, values for
>> + * these enums start at 0x10000. These values are then returned from
>> + * cmd_to_func() making it easy to implement the switch-case block in
>> + * papr_scm_ndctl(). These commands are sent to the kernel via
>> + * 'nd_papr_scm_cmd_pkg.hdr.nd_command'
>> + */
>
> With nd_family set to NVDIMM_FAMILY_PAPR_SCM the function number space
> can overlap the function numbers from other families.
Agree, will reset DSM_PAPR_SCM_MIN = 0 in next iteration.
>
>> +enum dsm_papr_scm {
>> +       DSM_PAPR_SCM_MIN =  0x10000,
>> +       DSM_PAPR_SCM_MAX,
>> +};
>> +
>> +/* Helpers to evaluate the size of PAPR_SCM envelope */
>> +/* Calculate the papr_scm-header size */
>> +#define ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE \
>> +       (sizeof(struct nd_papr_scm_cmd_pkg) - sizeof(struct nd_cmd_pkg))
>> +
>> +/* Given a type calculate envelope-content size (papr_scm-header + payload) */
>> +#define ND_PAPR_SCM_ENVELOPE_CONTENT_SIZE(_type_)      \
>> +       (sizeof(_type_) + ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE)
>> +
>> +/* Convert a libnvdimm nd_cmd_pkg to papr_scm specific pkg */
>> +static struct nd_papr_scm_cmd_pkg *nd_to_papr_cmd_pkg(struct nd_cmd_pkg *cmd)
>> +{
>> +       return (struct nd_papr_scm_cmd_pkg *) cmd;
>> +}
>> +
>> +/* Return the payload pointer for a given pcmd */
>> +static void *papr_scm_pcmd_to_payload(struct nd_papr_scm_cmd_pkg *pcmd)
>> +{
>> +       if (pcmd->hdr.nd_size_in == 0 && pcmd->hdr.nd_size_out == 0)
>> +               return NULL;
>> +       else
>> +               return (void *)((__u8 *) pcmd + pcmd->payload_offset);
>> +}
>> +#endif /* _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_ */
>> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
>> index aaf2e4ab1f75..e8ce96d2249e 100644
>> --- a/arch/powerpc/platforms/pseries/papr_scm.c
>> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
>> @@ -15,13 +15,15 @@
>>
>>  #include <asm/plpar_wrappers.h>
>>  #include <asm/papr_scm.h>
>> +#include <asm/papr_scm_dsm.h>
>>
>>  #define BIND_ANY_ADDR (~0ul)
>>
>>  #define PAPR_SCM_DIMM_CMD_MASK \
>>         ((1ul << ND_CMD_GET_CONFIG_SIZE) | \
>>          (1ul << ND_CMD_GET_CONFIG_DATA) | \
>> -        (1ul << ND_CMD_SET_CONFIG_DATA))
>> +        (1ul << ND_CMD_SET_CONFIG_DATA) | \
>> +        (1ul << ND_CMD_CALL))
>>
>>  struct papr_scm_priv {
>>         struct platform_device *pdev;
>> @@ -283,15 +285,92 @@ static int papr_scm_meta_set(struct papr_scm_priv *p,
>>         return 0;
>>  }
>>
>> +/*
>> + * Validate the inputs args to dimm-control function and return '0' if valid.
>> + * This also does initial sanity validation to ND_CMD_CALL sub-command packages.
>> + */
>> +static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
>> +                      unsigned int buf_len)
>> +{
>> +       unsigned long cmd_mask = PAPR_SCM_DIMM_CMD_MASK;
>> +       struct nd_papr_scm_cmd_pkg *pkg = nd_to_papr_cmd_pkg(buf);
>> +
>> +       /* Only dimm-specific calls are supported atm */
>> +       if (!nvdimm)
>> +               return -EINVAL;
>> +
>> +       if (!test_bit(cmd, &cmd_mask)) {
>> +               pr_debug("%s: Unsupported cmd=%u\n", __func__, cmd);
>
> Please convert all the pr_debug() statements in this file to
> dev_dbg(). Also you don't need to put the __func__ in the print
> statement because you can enable that via dynamic_debug_control see
> the "f" flag in addition to the "p" flag for dynamic debug enabling.
>
Fair suggestion. Will update in next iteration.

>> +               return -EINVAL;
>> +       } else if (cmd == ND_CMD_CALL) {
>> +
>> +               /* Verify the envelop package */
>
> s/envelop/envelope/
>
>> +               if (!buf || buf_len < sizeof(struct nd_papr_scm_cmd_pkg)) {
>> +                       pr_debug("%s: Invalid pkg size=%u\n", __func__,
>> +                                buf_len);
>> +                       return -EINVAL;
>> +               }
>> +
>> +               /* Verify that the DSM command family is valid */
>> +               if (pkg->hdr.nd_family != NVDIMM_FAMILY_PAPR_SCM) {
>> +                       pr_debug("%s: Invalid pkg family=0x%llx\n", __func__,
>> +                                pkg->hdr.nd_family);
>> +                       return -EINVAL;
>> +
>> +               }
>> +
>> +               /* We except a payload with all DSM commands */
>> +               if (papr_scm_pcmd_to_payload(pkg) == NULL) {
>> +                       pr_debug("%s: Empty payload for sub-command=0x%llx\n",
>> +                                __func__, pkg->hdr.nd_command);
>> +                       return -EINVAL;
>> +               }
>> +       }
>> +
>> +       /* Command looks valid */
>> +       return 0;
>> +}
>> +
>> +static int papr_scm_service_dsm(struct papr_scm_priv *p,
>> +                               struct nd_papr_scm_cmd_pkg *call_pkg)
>> +{
>> +       /* unknown subcommands return error in packages */
>> +       if (call_pkg->hdr.nd_command <= DSM_PAPR_SCM_MIN ||
>> +           call_pkg->hdr.nd_command >= DSM_PAPR_SCM_MAX) {
>> +               pr_debug("Invalid DSM command 0x%llx\n",
>> +                        call_pkg->hdr.nd_command);
>> +               call_pkg->cmd_status = -EINVAL;
>> +               return 0;
>> +       }
>> +
>> +       /* Depending on the DSM command call appropriate service routine */
>> +       switch (call_pkg->hdr.nd_command) {
>> +       default:
>> +               pr_debug("Unsupported DSM command 0x%llx\n",
>> +                        call_pkg->hdr.nd_command);
>> +               call_pkg->cmd_status = -ENOENT;
>> +               return 0;
>> +       }
>> +}
>> +
>>  int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
>>                 unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
>>  {
>>         struct nd_cmd_get_config_size *get_size_hdr;
>>         struct papr_scm_priv *p;
>> +       struct nd_papr_scm_cmd_pkg *call_pkg = NULL;
>> +       int rc;
>>
>> -       /* Only dimm-specific calls are supported atm */
>> -       if (!nvdimm)
>> -               return -EINVAL;
>> +       /* Use a local variable in case cmd_rc pointer is NULL */
>> +       if (cmd_rc == NULL)
>> +               cmd_rc = &rc;
>> +
>> +       *cmd_rc = is_cmd_valid(nvdimm, cmd, buf, buf_len);
>> +       if (*cmd_rc) {
>> +               pr_debug("%s: Invalid cmd=0x%x. Err=%d\n", __func__,
>> +                        cmd, *cmd_rc);
>> +               return *cmd_rc;
>> +       }
>>
>>         p = nvdimm_provider_data(nvdimm);
>>
>> @@ -313,13 +392,19 @@ int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
>>                 *cmd_rc = papr_scm_meta_set(p, buf);
>>                 break;
>>
>> +       case ND_CMD_CALL:
>> +               call_pkg = nd_to_papr_cmd_pkg(buf);
>> +               *cmd_rc = papr_scm_service_dsm(p, call_pkg);
>> +               break;
>> +
>>         default:
>> -               return -EINVAL;
>> +               dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
>> +               *cmd_rc = -EINVAL;
>>         }
>>
>>         dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
>>
>> -       return 0;
>> +       return *cmd_rc;
>>  }
>>
>>  static inline int papr_scm_node(int node)
>> --
>> 2.25.1
>>

Patch
diff mbox series

diff --git a/arch/powerpc/include/uapi/asm/papr_scm_dsm.h b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
new file mode 100644
index 000000000000..c039a49b41b4
--- /dev/null
+++ b/arch/powerpc/include/uapi/asm/papr_scm_dsm.h
@@ -0,0 +1,161 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * PAPR SCM Device specific methods and struct for libndctl and ndctl
+ *
+ * (C) Copyright IBM 2020
+ *
+ * Author: Vaibhav Jain <vaibhav at linux.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
+#define _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_
+
+#include <linux/types.h>
+
+#ifdef __KERNEL__
+#include <linux/ndctl.h>
+#else
+#include <ndctl.h>
+#endif
+
+/*
+ * DSM Envelope:
+ *
+ * The ioctl ND_CMD_CALL transfers data between user-space and kernel via
+ * 'envelopes' which consists of a header and user-defined payload sections.
+ * The header is described by 'struct nd_papr_scm_cmd_pkg' which expects a
+ * payload following it and offset of which relative to the struct is provided
+ * by 'nd_papr_scm_cmd_pkg.payload_offset'. *
+ *
+ *  +-------------+---------------------+---------------------------+
+ *  |   64-Bytes  |       8-Bytes       |       Max 184-Bytes       |
+ *  +-------------+---------------------+---------------------------+
+ *  |               nd_papr_scm_cmd_pkg |                           |
+ *  |-------------+                     |                           |
+ *  |  nd_cmd_pkg |                     |                           |
+ *  +-------------+---------------------+---------------------------+
+ *  | nd_family   |			|			    |
+ *  | nd_size_out | cmd_status          |			    |
+ *  | nd_size_in  | payload_version     |      PAYLOAD		    |
+ *  | nd_command  | payload_offset ----->			    |
+ *  | nd_fw_size  |                     |			    |
+ *  +-------------+---------------------+---------------------------+
+ *
+ * DSM Header:
+ *
+ * The header is defined as 'struct nd_papr_scm_cmd_pkg' which embeds a
+ * 'struct nd_cmd_pkg' instance. The DSM command is assigned to member
+ * 'nd_cmd_pkg.nd_command'. Apart from size information of the envelop which is
+ * contained in 'struct nd_cmd_pkg', the header also has members following
+ * members:
+ *
+ * 'cmd_status'		: (Out) Errors if any encountered while servicing DSM.
+ * 'payload_version'	: (In/Out) Version number associated with the payload.
+ * 'payload_offset'	: (In)Relative offset of payload from start of envelope.
+ *
+ * DSM Payload:
+ *
+ * The layout of the DSM Payload is defined by various structs shared between
+ * papr_scm and libndctl so that contents of payload can be interpreted. During
+ * servicing of a DSM the papr_scm module will read input args from the payload
+ * field by casting its contents to an appropriate struct pointer based on the
+ * DSM command. Similarly the output of servicing the DSM command will be copied
+ * to the payload field using the same struct.
+ *
+ * 'libnvdimm' enforces a hard limit of 256 bytes on the envelope size, which
+ * leaves around 184 bytes for the envelope payload (ignoring any padding that
+ * the compiler may silently introduce).
+ *
+ * Payload Version:
+ *
+ * A 'payload_version' field is present in DSM header that indicates a specific
+ * version of the structure present in DSM Payload for a given DSM command. This
+ * provides backward compatibility in case the DSM Payload structure evolves
+ * and different structures are supported by 'papr_scm' and 'libndctl'.
+ *
+ * When sending a DSM Payload to 'papr_scm', 'libndctl' should send the version
+ * of the payload struct it supports via 'payload_version' field. The 'papr_scm'
+ * module when servicing the DSM envelop checks the 'payload_version' and then
+ * uses 'payload struct version' == MIN('payload_version field',
+ * 'max payload-struct-version supported by papr_scm') to service the DSM. After
+ * servicing the DSM, 'papr_scm' put the negotiated version of payload struct in
+ * returned 'payload_version' field.
+ *
+ * Libndctl on receiving the envelop back from papr_scm again checks the
+ * 'payload_version' field and based on it use the appropriate version dsm
+ * struct to parse the results.
+ *
+ * Backward Compatibility:
+ *
+ * Above scheme of exchanging different versioned DSM struct between libndctl
+ * and papr_scm should provide backward compatibility until following two
+ * assumptions/conditions when defining new DSM structs hold:
+ *
+ * Let T(X) = { set of attributes in DSM struct 'T' versioned X }
+ *
+ * 1. T(X) is a proper subset of T(Y) if X > Y.
+ *    i.e Each new version of DSM struct should retain existing struct
+ *    attributes from previous version
+ *
+ * 2. If an entity (libndctl or papr_scm) supports a DSM struct T(X) then
+ *    it should also support T(1), T(2)...T(X - 1).
+ *    i.e When adding support for new version of a DSM struct, libndctl
+ *    and papr_scm should retain support of the existing DSM struct
+ *    version they support.
+ */
+
+/* Papr-scm-header + payload expected with ND_CMD_CALL ioctl from libnvdimm */
+struct nd_papr_scm_cmd_pkg {
+	struct nd_cmd_pkg hdr;		/* Package header containing sub-cmd */
+	__s32 cmd_status;		/* Out: Sub-cmd status returned back */
+	__u16 payload_offset;	/* In: offset from start of struct */
+	__u16 payload_version;	/* In/Out: version of the payload */
+	__u8 payload[];		/* In/Out: Sub-cmd data buffer */
+};
+
+/*
+ * Sub commands for ND_CMD_CALL. To prevent overlap from ND_CMD_*, values for
+ * these enums start at 0x10000. These values are then returned from
+ * cmd_to_func() making it easy to implement the switch-case block in
+ * papr_scm_ndctl(). These commands are sent to the kernel via
+ * 'nd_papr_scm_cmd_pkg.hdr.nd_command'
+ */
+enum dsm_papr_scm {
+	DSM_PAPR_SCM_MIN =  0x10000,
+	DSM_PAPR_SCM_MAX,
+};
+
+/* Helpers to evaluate the size of PAPR_SCM envelope */
+/* Calculate the papr_scm-header size */
+#define ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE \
+	(sizeof(struct nd_papr_scm_cmd_pkg) - sizeof(struct nd_cmd_pkg))
+
+/* Given a type calculate envelope-content size (papr_scm-header + payload) */
+#define ND_PAPR_SCM_ENVELOPE_CONTENT_SIZE(_type_)	\
+	(sizeof(_type_) + ND_PAPR_SCM_ENVELOPE_CONTENT_HDR_SIZE)
+
+/* Convert a libnvdimm nd_cmd_pkg to papr_scm specific pkg */
+static struct nd_papr_scm_cmd_pkg *nd_to_papr_cmd_pkg(struct nd_cmd_pkg *cmd)
+{
+	return (struct nd_papr_scm_cmd_pkg *) cmd;
+}
+
+/* Return the payload pointer for a given pcmd */
+static void *papr_scm_pcmd_to_payload(struct nd_papr_scm_cmd_pkg *pcmd)
+{
+	if (pcmd->hdr.nd_size_in == 0 && pcmd->hdr.nd_size_out == 0)
+		return NULL;
+	else
+		return (void *)((__u8 *) pcmd + pcmd->payload_offset);
+}
+#endif /* _UAPI_ASM_POWERPC_PAPR_SCM_DSM_H_ */
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index aaf2e4ab1f75..e8ce96d2249e 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -15,13 +15,15 @@ 
 
 #include <asm/plpar_wrappers.h>
 #include <asm/papr_scm.h>
+#include <asm/papr_scm_dsm.h>
 
 #define BIND_ANY_ADDR (~0ul)
 
 #define PAPR_SCM_DIMM_CMD_MASK \
 	((1ul << ND_CMD_GET_CONFIG_SIZE) | \
 	 (1ul << ND_CMD_GET_CONFIG_DATA) | \
-	 (1ul << ND_CMD_SET_CONFIG_DATA))
+	 (1ul << ND_CMD_SET_CONFIG_DATA) | \
+	 (1ul << ND_CMD_CALL))
 
 struct papr_scm_priv {
 	struct platform_device *pdev;
@@ -283,15 +285,92 @@  static int papr_scm_meta_set(struct papr_scm_priv *p,
 	return 0;
 }
 
+/*
+ * Validate the inputs args to dimm-control function and return '0' if valid.
+ * This also does initial sanity validation to ND_CMD_CALL sub-command packages.
+ */
+static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
+		       unsigned int buf_len)
+{
+	unsigned long cmd_mask = PAPR_SCM_DIMM_CMD_MASK;
+	struct nd_papr_scm_cmd_pkg *pkg = nd_to_papr_cmd_pkg(buf);
+
+	/* Only dimm-specific calls are supported atm */
+	if (!nvdimm)
+		return -EINVAL;
+
+	if (!test_bit(cmd, &cmd_mask)) {
+		pr_debug("%s: Unsupported cmd=%u\n", __func__, cmd);
+		return -EINVAL;
+	} else if (cmd == ND_CMD_CALL) {
+
+		/* Verify the envelop package */
+		if (!buf || buf_len < sizeof(struct nd_papr_scm_cmd_pkg)) {
+			pr_debug("%s: Invalid pkg size=%u\n", __func__,
+				 buf_len);
+			return -EINVAL;
+		}
+
+		/* Verify that the DSM command family is valid */
+		if (pkg->hdr.nd_family != NVDIMM_FAMILY_PAPR_SCM) {
+			pr_debug("%s: Invalid pkg family=0x%llx\n", __func__,
+				 pkg->hdr.nd_family);
+			return -EINVAL;
+
+		}
+
+		/* We except a payload with all DSM commands */
+		if (papr_scm_pcmd_to_payload(pkg) == NULL) {
+			pr_debug("%s: Empty payload for sub-command=0x%llx\n",
+				 __func__, pkg->hdr.nd_command);
+			return -EINVAL;
+		}
+	}
+
+	/* Command looks valid */
+	return 0;
+}
+
+static int papr_scm_service_dsm(struct papr_scm_priv *p,
+				struct nd_papr_scm_cmd_pkg *call_pkg)
+{
+	/* unknown subcommands return error in packages */
+	if (call_pkg->hdr.nd_command <= DSM_PAPR_SCM_MIN ||
+	    call_pkg->hdr.nd_command >= DSM_PAPR_SCM_MAX) {
+		pr_debug("Invalid DSM command 0x%llx\n",
+			 call_pkg->hdr.nd_command);
+		call_pkg->cmd_status = -EINVAL;
+		return 0;
+	}
+
+	/* Depending on the DSM command call appropriate service routine */
+	switch (call_pkg->hdr.nd_command) {
+	default:
+		pr_debug("Unsupported DSM command 0x%llx\n",
+			 call_pkg->hdr.nd_command);
+		call_pkg->cmd_status = -ENOENT;
+		return 0;
+	}
+}
+
 int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
 		unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
 {
 	struct nd_cmd_get_config_size *get_size_hdr;
 	struct papr_scm_priv *p;
+	struct nd_papr_scm_cmd_pkg *call_pkg = NULL;
+	int rc;
 
-	/* Only dimm-specific calls are supported atm */
-	if (!nvdimm)
-		return -EINVAL;
+	/* Use a local variable in case cmd_rc pointer is NULL */
+	if (cmd_rc == NULL)
+		cmd_rc = &rc;
+
+	*cmd_rc = is_cmd_valid(nvdimm, cmd, buf, buf_len);
+	if (*cmd_rc) {
+		pr_debug("%s: Invalid cmd=0x%x. Err=%d\n", __func__,
+			 cmd, *cmd_rc);
+		return *cmd_rc;
+	}
 
 	p = nvdimm_provider_data(nvdimm);
 
@@ -313,13 +392,19 @@  int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
 		*cmd_rc = papr_scm_meta_set(p, buf);
 		break;
 
+	case ND_CMD_CALL:
+		call_pkg = nd_to_papr_cmd_pkg(buf);
+		*cmd_rc = papr_scm_service_dsm(p, call_pkg);
+		break;
+
 	default:
-		return -EINVAL;
+		dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
+		*cmd_rc = -EINVAL;
 	}
 
 	dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
 
-	return 0;
+	return *cmd_rc;
 }
 
 static inline int papr_scm_node(int node)