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Subject[PATCH v2 1/1] powerpc/pseries: Interface to represent PAPR firmware attributes
Date
Adds a generic interface to represent the energy and frequency related
PAPR attributes on the system using the new H_CALL
"H_GET_ENERGY_SCALE_INFO".

H_GET_EM_PARMS H_CALL was previously responsible for exporting this
information in the lparcfg, however the H_GET_EM_PARMS H_CALL
will be deprecated P10 onwards.

The H_GET_ENERGY_SCALE_INFO H_CALL is of the following call format:
hcall(
uint64 H_GET_ENERGY_SCALE_INFO, // Get energy scale info
uint64 flags, // Per the flag request
uint64 firstAttributeId,// The attribute id
uint64 bufferAddress, // Guest physical address of the output buffer
uint64 bufferSize // The size in bytes of the output buffer
);

This H_CALL can query either all the attributes at once with
firstAttributeId = 0, flags = 0 as well as query only one attribute
at a time with firstAttributeId = id, flags = 1.

The output buffer consists of the following
1. number of attributes - 8 bytes
2. array offset to the data location - 8 bytes
3. version info - 1 byte
4. A data array of size num attributes, which contains the following:
a. attribute ID - 8 bytes
b. attribute value in number - 8 bytes
c. attribute name in string - 64 bytes
d. attribute value in string - 64 bytes

The new H_CALL exports information in direct string value format, hence
a new interface has been introduced in
/sys/firmware/papr/energy_scale_info to export this information to
userspace in an extensible pass-through format.

The H_CALL returns the name, numeric value and string value (if exists)

The format of exposing the sysfs information is as follows:
/sys/firmware/papr/energy_scale_info/
|-- <id>/
|-- desc
|-- value
|-- value_desc (if exists)
|-- <id>/
|-- desc
|-- value
|-- value_desc (if exists)
...

The energy information that is exported is useful for userspace tools
such as powerpc-utils. Currently these tools infer the
"power_mode_data" value in the lparcfg, which in turn is obtained from
the to be deprecated H_GET_EM_PARMS H_CALL.
On future platforms, such userspace utilities will have to look at the
data returned from the new H_CALL being populated in this new sysfs
interface and report this information directly without the need of
interpretation.

Signed-off-by: Pratik R. Sampat <psampat@linux.ibm.com>
---
.../sysfs-firmware-papr-energy-scale-info | 26 ++
arch/powerpc/include/asm/hvcall.h | 23 +-
arch/powerpc/kvm/trace_hv.h | 1 +
arch/powerpc/platforms/pseries/Makefile | 3 +-
.../pseries/papr_platform_attributes.c | 320 ++++++++++++++++++
5 files changed, 371 insertions(+), 2 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info
create mode 100644 arch/powerpc/platforms/pseries/papr_platform_attributes.c

diff --git a/Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info b/Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info
new file mode 100644
index 000000000000..fd82f2bfafe5
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-papr-energy-scale-info
@@ -0,0 +1,26 @@
+What: /sys/firmware/papr/energy_scale_info
+Date: June 2021
+Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description: Directory hosting a set of platform attributes like
+ energy/frequency on Linux running as a PAPR guest.
+
+ Each file in a directory contains a platform
+ attribute hierarchy pertaining to performance/
+ energy-savings mode and processor frequency.
+
+What: /sys/firmware/papr/energy_scale_info/<id>
+ /sys/firmware/papr/energy_scale_info/<id>/desc
+ /sys/firmware/papr/energy_scale_info/<id>/value
+ /sys/firmware/papr/energy_scale_info/<id>/value_desc
+Date: June 2021
+Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description: Energy, frequency attributes directory for POWERVM servers
+
+ This directory provides energy, erequency, folding information. It
+ contains below sysfs attributes:
+
+ - desc: String description of the attribute <id>
+
+ - value: Numeric value of attribute <id>
+
+ - value_desc: String value of attribute <id>
diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index e3b29eda8074..25a6b744d41e 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -316,7 +316,8 @@
#define H_SCM_PERFORMANCE_STATS 0x418
#define H_RPT_INVALIDATE 0x448
#define H_SCM_FLUSH 0x44C
-#define MAX_HCALL_OPCODE H_SCM_FLUSH
+#define H_GET_ENERGY_SCALE_INFO 0x450
+#define MAX_HCALL_OPCODE H_GET_ENERGY_SCALE_INFO

/* Scope args for H_SCM_UNBIND_ALL */
#define H_UNBIND_SCOPE_ALL (0x1)
@@ -631,6 +632,26 @@ struct hv_gpci_request_buffer {
uint8_t bytes[HGPCI_MAX_DATA_BYTES];
} __packed;

+#define MAX_ESI_ATTRS 10
+#define MAX_BUF_SZ (sizeof(struct h_energy_scale_info_hdr) + \
+ (sizeof(struct energy_scale_attribute) * MAX_ESI_ATTRS))
+
+struct energy_scale_attribute {
+ __be64 id;
+ __be64 value;
+ unsigned char desc[64];
+ unsigned char value_desc[64];
+} __packed;
+
+struct h_energy_scale_info_hdr {
+ __be64 num_attrs;
+ __be64 array_offset;
+ __u8 data_header_version;
+} __packed;
+
+/* /sys/firmware/papr */
+extern struct kobject *papr_kobj;
+
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_HVCALL_H */
diff --git a/arch/powerpc/kvm/trace_hv.h b/arch/powerpc/kvm/trace_hv.h
index 830a126e095d..38cd0ed0a617 100644
--- a/arch/powerpc/kvm/trace_hv.h
+++ b/arch/powerpc/kvm/trace_hv.h
@@ -115,6 +115,7 @@
{H_VASI_STATE, "H_VASI_STATE"}, \
{H_ENABLE_CRQ, "H_ENABLE_CRQ"}, \
{H_GET_EM_PARMS, "H_GET_EM_PARMS"}, \
+ {H_GET_ENERGY_SCALE_INFO, "H_GET_ENERGY_SCALE_INFO"}, \
{H_SET_MPP, "H_SET_MPP"}, \
{H_GET_MPP, "H_GET_MPP"}, \
{H_HOME_NODE_ASSOCIATIVITY, "H_HOME_NODE_ASSOCIATIVITY"}, \
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index c8a2b0b05ac0..d14fca89ac25 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -6,7 +6,8 @@ obj-y := lpar.o hvCall.o nvram.o reconfig.o \
of_helpers.o \
setup.o iommu.o event_sources.o ras.o \
firmware.o power.o dlpar.o mobility.o rng.o \
- pci.o pci_dlpar.o eeh_pseries.o msi.o
+ pci.o pci_dlpar.o eeh_pseries.o msi.o \
+ papr_platform_attributes.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_SCANLOG) += scanlog.o
obj-$(CONFIG_KEXEC_CORE) += kexec.o
diff --git a/arch/powerpc/platforms/pseries/papr_platform_attributes.c b/arch/powerpc/platforms/pseries/papr_platform_attributes.c
new file mode 100644
index 000000000000..117801bd7e76
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/papr_platform_attributes.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Platform energy and frequency attributes driver
+ *
+ * This driver creates a sys file at /sys/firmware/papr/ which encapsulates a
+ * directory structure containing files in keyword - value pairs that specify
+ * energy and frequency configuration of the system.
+ *
+ * The format of exposing the sysfs information is as follows:
+ * /sys/firmware/papr/energy_scale_info/
+ * |-- <id>/
+ * |-- desc
+ * |-- value
+ * |-- value_desc (if exists)
+ * |-- <id>/
+ * |-- desc
+ * |-- value
+ * |-- value_desc (if exists)
+ *
+ * Copyright 2021 IBM Corp.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/hugetlb.h>
+#include <asm/lppaca.h>
+#include <asm/hvcall.h>
+#include <asm/firmware.h>
+#include <asm/time.h>
+#include <asm/prom.h>
+#include <asm/vdso_datapage.h>
+#include <asm/vio.h>
+#include <asm/mmu.h>
+#include <asm/machdep.h>
+#include <asm/drmem.h>
+
+#include "pseries.h"
+
+#define MAX_ATTRS 3
+#define MAX_NAME_LEN 16
+
+/*
+ * Flag attributes to fetch either all or one attribute from the HCALL
+ * flag = BE(0) => fetch all attributes with firstAttributeId = 0
+ * flag = BE(1) => fetch a single attribute with firstAttributeId = id
+ */
+#define ESI_FLAGS_ALL 0
+#define ESI_FLAGS_SINGLE PPC_BIT(0)
+
+struct papr_attr {
+ u64 id;
+ struct kobj_attribute kobj_attr;
+};
+struct papr_group {
+ char name[MAX_NAME_LEN];
+ struct attribute_group pg;
+ struct papr_attr *pgattrs;
+} *pgs;
+
+/* /sys/firmware/papr */
+struct kobject *papr_kobj;
+/* /sys/firmware/papr/energy_scale_info */
+struct kobject *esi_kobj;
+
+struct h_energy_scale_info_hdr *esi_hdr;
+struct energy_scale_attribute *esi_attrs;
+
+/*
+ * Extract and export the description of the energy scale attribute
+ *
+ * As We do not expect the name to change, hence use the old description and
+ * save a call to the H_GET_ENERGY_SCALE_INFO HCALL
+ */
+static ssize_t papr_show_desc(struct kobject *kobj,
+ struct kobj_attribute *kobj_attr,
+ char *buf)
+{
+ struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+ kobj_attr);
+ int idx, ret = 0;
+
+ for (idx = 0; idx < be64_to_cpu(esi_hdr->num_attrs); idx++) {
+ if (pattr->id == be64_to_cpu(esi_attrs[idx].id)) {
+ ret = sprintf(buf, "%s\n", esi_attrs[idx].desc);
+ if (ret < 0)
+ ret = -EIO;
+ break;
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * Extract and export the numeric value of the energy scale attributes
+ */
+static ssize_t papr_show_value(struct kobject *kobj,
+ struct kobj_attribute *kobj_attr,
+ char *buf)
+{
+ struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+ kobj_attr);
+ char *t_buf;
+ struct h_energy_scale_info_hdr *t_hdr;
+ struct energy_scale_attribute *t_esi;
+ int ret = 0;
+
+ t_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+ if (t_buf == NULL)
+ return -ENOMEM;
+
+ ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
+ pattr->id, virt_to_phys(t_buf),
+ MAX_BUF_SZ);
+
+ if (ret != H_SUCCESS) {
+ pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+ goto out;
+ }
+
+ t_hdr = (struct h_energy_scale_info_hdr *) t_buf;
+ t_esi = (struct energy_scale_attribute *)
+ (t_buf + be64_to_cpu(t_hdr->array_offset));
+
+ ret = sprintf(buf, "%llu\n", be64_to_cpu(t_esi->value));
+ if (ret < 0)
+ ret = -EIO;
+out:
+ kfree(t_buf);
+
+ return ret;
+}
+
+/*
+ * Extract and export the value description in string format of the energy
+ * scale attributes
+ */
+static ssize_t papr_show_value_desc(struct kobject *kobj,
+ struct kobj_attribute *kobj_attr,
+ char *buf)
+{
+ struct papr_attr *pattr = container_of(kobj_attr, struct papr_attr,
+ kobj_attr);
+ char *t_buf;
+ struct h_energy_scale_info_hdr *t_hdr;
+ struct energy_scale_attribute *t_esi;
+ int ret = 0;
+
+ t_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+ if (t_buf == NULL)
+ return -ENOMEM;
+
+ ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_SINGLE,
+ pattr->id, virt_to_phys(t_buf),
+ MAX_BUF_SZ);
+
+ if (ret != H_SUCCESS) {
+ pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+ goto out;
+ }
+
+ t_hdr = (struct h_energy_scale_info_hdr *) t_buf;
+ t_esi = (struct energy_scale_attribute *)
+ (t_buf + be64_to_cpu(t_hdr->array_offset));
+
+ ret = sprintf(buf, "%s\n", t_esi->value_desc);
+ if (ret < 0)
+ ret = -EIO;
+out:
+ kfree(t_buf);
+
+ return ret;
+}
+
+static struct papr_ops_info {
+ const char *attr_name;
+ ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *kobj_attr,
+ char *buf);
+} ops_info[MAX_ATTRS] = {
+ { "desc", papr_show_desc },
+ { "value", papr_show_value },
+ { "value_desc", papr_show_value_desc },
+};
+
+static void add_attr(u64 id, int index, struct papr_attr *attr)
+{
+ attr->id = id;
+ sysfs_attr_init(&attr->kobj_attr.attr);
+ attr->kobj_attr.attr.name = ops_info[index].attr_name;
+ attr->kobj_attr.attr.mode = 0444;
+ attr->kobj_attr.show = ops_info[index].show;
+}
+
+static int add_attr_group(u64 id, int len, struct papr_group *pg,
+ bool show_val_desc)
+{
+ int i;
+
+ for (i = 0; i < len; i++) {
+ if (!strcmp(ops_info[i].attr_name, "value_desc") &&
+ !show_val_desc) {
+ continue;
+ }
+ add_attr(id, i, &pg->pgattrs[i]);
+ pg->pg.attrs[i] = &pg->pgattrs[i].kobj_attr.attr;
+ }
+
+ return sysfs_create_group(esi_kobj, &pg->pg);
+}
+
+static int __init papr_init(void)
+{
+ uint64_t num_attrs;
+ int ret, idx, i;
+ char *esi_buf;
+
+ if (!firmware_has_feature(FW_FEATURE_LPAR))
+ return -ENXIO;
+
+ esi_buf = kmalloc(MAX_BUF_SZ, GFP_KERNEL);
+ if (esi_buf == NULL)
+ return -ENOMEM;
+ /*
+ * hcall(
+ * uint64 H_GET_ENERGY_SCALE_INFO, // Get energy scale info
+ * uint64 flags, // Per the flag request
+ * uint64 firstAttributeId, // The attribute id
+ * uint64 bufferAddress, // Guest physical address of the output buffer
+ * uint64 bufferSize); // The size in bytes of the output buffer
+ */
+ ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, ESI_FLAGS_ALL, 0,
+ virt_to_phys(esi_buf), MAX_BUF_SZ);
+ if (ret != H_SUCCESS) {
+ pr_warn("hcall failed: H_GET_ENERGY_SCALE_INFO");
+ goto out;
+ }
+
+ esi_hdr = (struct h_energy_scale_info_hdr *) esi_buf;
+ num_attrs = be64_to_cpu(esi_hdr->num_attrs);
+ /*
+ * Typecast the energy buffer to the attribute structure at the offset
+ * specified in the buffer
+ */
+ esi_attrs = (struct energy_scale_attribute *)
+ (esi_buf + be64_to_cpu(esi_hdr->array_offset));
+
+ pgs = kcalloc(num_attrs, sizeof(*pgs), GFP_KERNEL);
+ if (!pgs)
+ goto out_pgs;
+
+ papr_kobj = kobject_create_and_add("papr", firmware_kobj);
+ if (!papr_kobj) {
+ pr_warn("kobject_create_and_add papr failed\n");
+ goto out_kobj;
+ }
+
+ esi_kobj = kobject_create_and_add("energy_scale_info", papr_kobj);
+ if (!esi_kobj) {
+ pr_warn("kobject_create_and_add energy_scale_info failed\n");
+ goto out_ekobj;
+ }
+
+ for (idx = 0; idx < num_attrs; idx++) {
+ char buf[4];
+ bool show_val_desc = true;
+
+ pgs[idx].pgattrs = kcalloc(MAX_ATTRS,
+ sizeof(*pgs[idx].pgattrs),
+ GFP_KERNEL);
+ if (!pgs[idx].pgattrs)
+ goto out_kobj;
+
+ pgs[idx].pg.attrs = kcalloc(MAX_ATTRS + 1,
+ sizeof(*pgs[idx].pg.attrs),
+ GFP_KERNEL);
+ if (!pgs[idx].pg.attrs) {
+ kfree(pgs[idx].pgattrs);
+ goto out_kobj;
+ }
+
+ sprintf(buf, "%lld", be64_to_cpu(esi_attrs[idx].id));
+ pgs[idx].pg.name = buf;
+
+ /* Do not add the value description if it does not exist */
+ if (strlen(esi_attrs[idx].value_desc) == 0)
+ show_val_desc = false;
+
+ if (add_attr_group(be64_to_cpu(esi_attrs[idx].id),
+ MAX_ATTRS, &pgs[idx], show_val_desc)) {
+ pr_warn("Failed to create papr attribute group %s\n",
+ pgs[idx].pg.name);
+ goto out_pgattrs;
+ }
+ }
+
+ return 0;
+
+out_pgattrs:
+ for (i = 0; i < MAX_ATTRS; i++) {
+ kfree(pgs[i].pgattrs);
+ kfree(pgs[i].pg.attrs);
+ }
+out_ekobj:
+ kobject_put(esi_kobj);
+out_kobj:
+ kobject_put(papr_kobj);
+out_pgs:
+ kfree(pgs);
+out:
+ kfree(esi_buf);
+
+ return -ENOMEM;
+}
+
+machine_device_initcall(pseries, papr_init);
--
2.31.1
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