[PATCH v3 3/4] powerpc/papr_scm, uapi: Add support for handling PAPR DSM commands
Vaibhav Jain
vaibhav at linux.ibm.com
Mon Mar 30 22:09:42 AEDT 2020
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() easier via a simplified switch-case
block. For this a new function cmd_to_func() is implemented that reads
the args to papr_scm_ndctl() , performs sanity tests on them and
converts them to PAPR DSM commands which can then be handled via the
switch-case block.
Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
---
Changelog:
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 | 87 +++++++++-
2 files changed, 241 insertions(+), 7 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..9a2614aaae88 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;
@@ -283,19 +285,82 @@ static int papr_scm_meta_set(struct papr_scm_priv *p,
return 0;
}
+/*
+ * Validate the input to dimm-control function and return papr_scm specific
+ * commands. This does sanity validation to ND_CMD_CALL sub-command packages.
+ */
+static int cmd_to_func(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) {
+ return cmd;
+ }
+
+ /* cmd == ND_CMD_CALL so 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;
+ }
+
+ 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;
+
+ }
+
+ if (pkg->hdr.nd_command <= DSM_PAPR_SCM_MIN ||
+ pkg->hdr.nd_command >= DSM_PAPR_SCM_MAX) {
+
+ /* for unknown subcommands return ND_CMD_CALL */
+ pr_debug("%s: Unknown sub-command=0x%llx\n", __func__,
+ pkg->hdr.nd_command);
+ return ND_CMD_CALL;
+ }
+
+ /* We except a payload with all DSM commands */
+ if (papr_scm_pcmd_to_payload(pkg) == NULL) {
+ pr_debug("%s: Empty patload for sub-command=0x%llx\n", __func__,
+ pkg->hdr.nd_command);
+ return -EINVAL;
+ }
+
+ /* Return the DSM_PAPR_SCM_* command */
+ return pkg->hdr.nd_command;
+}
+
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 cmd_in, 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_in = cmd_to_func(nvdimm, cmd, buf, buf_len);
+ if (cmd_in < 0) {
+ pr_debug("%s: Invalid cmd=%u. Err=%d\n", __func__, cmd, cmd_in);
+ return cmd_in;
+ }
p = nvdimm_provider_data(nvdimm);
- switch (cmd) {
+ switch (cmd_in) {
case ND_CMD_GET_CONFIG_SIZE:
get_size_hdr = buf;
@@ -313,13 +378,21 @@ 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:
+ /* This happens if subcommand package sanity fails */
+ call_pkg = nd_to_papr_cmd_pkg(buf);
+ call_pkg->cmd_status = -ENOENT;
+ *cmd_rc = 0;
+ break;
+
default:
- return -EINVAL;
+ dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd_in);
+ *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)
--
2.24.1
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