[RFC] powerpc/pseries: Interface to represent PAPR firmware attributes
Pratik Sampat
psampat at linux.ibm.com
Wed Jun 9 02:42:19 AEST 2021
I've implemented a POC using this interface for the powerpc-utils'
ppc64_cpu --frequency command-line tool to utilize this information
in userspace.
The POC has been hosted here:
https://github.com/pratiksampat/powerpc-utils/tree/H_GET_ENERGY_SCALE_INFO
and based on comments I suggestions I can further improve the
parsing logic from this initial implementation.
Sample output from the powerpc-utils tool is as follows:
# ppc64_cpu --frequency
Power and Performance Mode: XXXX
Idle Power Saver Status : XXXX
Processor Folding Status : XXXX --> Printed if Idle power save status is supported
Platform reported frequencies --> Frequencies reported from the platform's H_CALL i.e PAPR interface
min : NNNN GHz
max : NNNN GHz
static : NNNN GHz
Tool Computed frequencies
min : NNNN GHz (cpu XX)
max : NNNN GHz (cpu XX)
avg : NNNN GHz
On 04/06/21 10:05 pm, Pratik R. Sampat wrote:
> 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, // The logical 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
>
> 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 to export
> this information to userspace in an extensible pass-through format.
> The H_CALL returns the name, numeric value and string value. As string
> values are in human readable format, therefore if the string value
> exists then that is given precedence over the numeric value.
>
> The format of exposing the sysfs information is as follows:
> /sys/firmware/papr/
> |-- attr_0_name
> |-- attr_0_val
> |-- attr_1_name
> |-- attr_1_val
> ...
>
> 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 at linux.ibm.com>
> ---
> Documentation/ABI/testing/sysfs-firmware-papr | 24 +++
> arch/powerpc/include/asm/hvcall.h | 21 +-
> arch/powerpc/kvm/trace_hv.h | 1 +
> arch/powerpc/platforms/pseries/Makefile | 3 +-
> .../pseries/papr_platform_attributes.c | 203 ++++++++++++++++++
> 5 files changed, 250 insertions(+), 2 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-firmware-papr
> create mode 100644 arch/powerpc/platforms/pseries/papr_platform_attributes.c
>
> diff --git a/Documentation/ABI/testing/sysfs-firmware-papr b/Documentation/ABI/testing/sysfs-firmware-papr
> new file mode 100644
> index 000000000000..1c040b44ac3b
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-firmware-papr
> @@ -0,0 +1,24 @@
> +What: /sys/firmware/papr
> +Date: June 2021
> +Contact: Linux for PowerPC mailing list <linuxppc-dev at ozlabs.org>
> +Description : Director hosting a set of platform attributes on Linux
> + running as a PAPR guest.
> +
> + Each file in a directory contains a platform
> + attribute pertaining to performance/energy-savings
> + mode and processor frequency.
> +
> +What: /sys/firmware/papr/attr_X_name
> + /sys/firmware/papr/attr_X_val
> +Date: June 2021
> +Contact: Linux for PowerPC mailing list <linuxppc-dev at ozlabs.org>
> +Description: PAPR attributes directory for POWERVM servers
> +
> + This directory provides PAPR information. It
> + contains below sysfs attributes:
> +
> + - attr_X_name: File contains the name of
> + attribute X
> +
> + - attr_X_val: Numeric/string value of
> + attribute X
> diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
> index e3b29eda8074..19a2a8c77a49 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 +632,24 @@ struct hv_gpci_request_buffer {
> uint8_t bytes[HGPCI_MAX_DATA_BYTES];
> } __packed;
>
> +#define MAX_EM_ATTRS 10
> +#define MAX_EM_DATA_BYTES \
> + (sizeof(struct energy_scale_attributes) * MAX_EM_ATTRS)
> +struct energy_scale_attributes {
> + __be64 attr_id;
> + __be64 attr_value;
> + unsigned char attr_desc[64];
> + unsigned char attr_value_desc[64];
> +} __packed;
> +
> +struct hv_energy_scale_buffer {
> + __be64 num_attr;
> + __be64 array_offset;
> + __u8 data_header_version;
> + unsigned char data[MAX_EM_DATA_BYTES];
> +} __packed;
> +
> +
> #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..8818877ff47e
> --- /dev/null
> +++ b/arch/powerpc/platforms/pseries/papr_platform_attributes.c
> @@ -0,0 +1,203 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * PowerPC64 LPAR PAPR Information Driver
> + *
> + * This driver creates a sys file at /sys/firmware/papr/ which contains
> + * files keyword - value pairs that specify energy configuration of the system.
> + *
> + * 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_KOBJ_ATTRS 2
> +
> +struct papr_attr {
> + u64 id;
> + struct kobj_attribute attr;
> +} *pgattrs;
> +
> +struct kobject *papr_kobj;
> +struct hv_energy_scale_buffer *em_buf;
> +struct energy_scale_attributes *ea;
> +
> +static ssize_t papr_show_name(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + struct papr_attr *pattr = container_of(attr, struct papr_attr, attr);
> + int idx, ret = 0;
> +
> + /*
> + * We do not expect the name to change, hence use the old value
> + * and save a HCALL
> + */
> + for (idx = 0; idx < be64_to_cpu(em_buf->num_attr); idx++) {
> + if (pattr->id == be64_to_cpu(ea[idx].attr_id)) {
> + ret = sprintf(buf, "%s\n", ea[idx].attr_desc);
> + if (ret < 0)
> + ret = -EIO;
> + break;
> + }
> + }
> +
> + return ret;
> +}
> +
> +static ssize_t papr_show_val(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + struct papr_attr *pattr = container_of(attr, struct papr_attr, attr);
> + struct hv_energy_scale_buffer *t_buf;
> + struct energy_scale_attributes *t_ea;
> + int data_offset, ret = 0;
> +
> + t_buf = kmalloc(sizeof(*t_buf), GFP_KERNEL);
> + if (t_buf == NULL)
> + return -ENOMEM;
> +
> + ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, 0,
> + pattr->id, virt_to_phys(t_buf),
> + sizeof(*t_buf));
> +
> + if (ret != H_SUCCESS) {
> + pr_warn("hcall faiiled: H_GET_ENERGY_SCALE_INFO");
> + goto out;
> + }
> +
> + data_offset = be64_to_cpu(t_buf->array_offset) -
> + (sizeof(t_buf->num_attr) +
> + sizeof(t_buf->array_offset) +
> + sizeof(t_buf->data_header_version));
> +
> + t_ea = (struct energy_scale_attributes *) &t_buf->data[data_offset];
> +
> + /* Prioritize string values over numerical */
> + if (strlen(t_ea->attr_value_desc) != 0)
> + ret = sprintf(buf, "%s\n", t_ea->attr_value_desc);
> + else
> + ret = sprintf(buf, "%llu\n", be64_to_cpu(t_ea->attr_value));
> + 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 *attr,
> + char *buf);
> +} ops_info[MAX_KOBJ_ATTRS] = {
> + { "name", papr_show_name },
> + { "val", papr_show_val },
> +};
> +
> +static int __init papr_init(void)
> +{
> + uint64_t num_attr;
> + int ret, idx, i, data_offset;
> +
> + em_buf = kmalloc(sizeof(*em_buf), GFP_KERNEL);
> + if (em_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, // The logical address of the output buffer
> + * uint64 bufferSize); // The size in bytes of the output buffer
> + */
> + ret = plpar_hcall_norets(H_GET_ENERGY_SCALE_INFO, 0, 0,
> + virt_to_phys(em_buf), sizeof(*em_buf));
> +
> + if (!firmware_has_feature(FW_FEATURE_LPAR) || ret != H_SUCCESS ||
> + em_buf->data_header_version != 0x1) {
> + pr_warn("hcall faiiled: H_GET_ENERGY_SCALE_INFO");
> + goto out;
> + }
> +
> + num_attr = be64_to_cpu(em_buf->num_attr);
> +
> + /*
> + * Typecast the energy buffer to the attribute structure at the offset
> + * specified in the buffer
> + */
> + data_offset = be64_to_cpu(em_buf->array_offset) -
> + (sizeof(em_buf->num_attr) +
> + sizeof(em_buf->array_offset) +
> + sizeof(em_buf->data_header_version));
> +
> + ea = (struct energy_scale_attributes *) &em_buf->data[data_offset];
> +
> + papr_kobj = kobject_create_and_add("papr", firmware_kobj);
> + if (!papr_kobj) {
> + pr_warn("kobject_create_and_add papr failed\n");
> + goto out_kobj;
> + }
> +
> + for (idx = 0; idx < num_attr; idx++) {
> + pgattrs = kcalloc(MAX_KOBJ_ATTRS,
> + sizeof(*pgattrs),
> + GFP_KERNEL);
> + if (!pgattrs)
> + goto out_kobj;
> +
> + /*
> + * Create the sysfs attribute hierarchy for each PAPR
> + * property found
> + */
> + for (i = 0; i < MAX_KOBJ_ATTRS; i++) {
> + char buf[20];
> +
> + pgattrs[i].id = be64_to_cpu(ea[idx].attr_id);
> + sysfs_attr_init(&pgattrs[i].attr.attr);
> + sprintf(buf, "%s_%d_%s", "attr", idx,
> + ops_info[i].attr_name);
> + pgattrs[i].attr.attr.name = buf;
> + pgattrs[i].attr.attr.mode = 0444;
> + pgattrs[i].attr.show = ops_info[i].show;
> +
> + if (sysfs_create_file(papr_kobj, &pgattrs[i].attr.attr)) {
> + pr_warn("Failed to create papr file %s\n",
> + pgattrs[i].attr.attr.name);
> + goto out_pgattrs;
> + }
> + }
> + }
> +
> + return 0;
> +
> +out_pgattrs:
> + for (i = 0; i < MAX_KOBJ_ATTRS; i++)
> + kfree(pgattrs);
> +out_kobj:
> + kobject_put(papr_kobj);
> +out:
> + kfree(em_buf);
> +
> + return -ENOMEM;
> +}
> +
> +machine_device_initcall(pseries, papr_init);
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