[PATCH v6 2/3] powerpc/pseries: Export hardware trace macro dump via debugfs

Tue Jan 14 01:19:06 AEDT 2025

> On 13 Jan 2025, at 4:10 PM, adubey at linux.ibm.com wrote:
> 
> From: Abhishek Dubey <adubey at linux.ibm.com>
> 
> This patch adds debugfs interface to export Hardware Trace Macro (HTM)
> function data in a LPAR. New hypervisor call "H_HTM" has been
> defined to setup, configure, control and dump the HTM data.
> This patch supports only dumping of HTM data in a LPAR.
> New debugfs folder called "htmdump" has been added under
> /sys/kernel/debug/arch path which contains files need to
> pass required parameters for the H_HTM dump function. New Kconfig
> option called "CONFIG_HTMDUMP" is added in platform/pseries
> for the same.
> 
> With this module loaded, list of files in debugfs path
> 
> /sys/kernel/debug/powerpc/htmdump
> coreindexonchip  htmtype  nodalchipindex  nodeindex  trace
> 
> Changelog:
>  v5->v6 : Header file inclusion
>  v4->v5 : Removed offset from available calculation, as offset is
>           always zero leading to buffur size reads.
>           Edited comments and commit message
> 
> v3 patch:
>  https://lore.kernel.org/linuxppc-dev/20240828085223.42177-2-maddy@linux.ibm.com/

Please move the Changelog and v3 patch reference to below where it won’t come as part of git log

> 
> Signed-off-by: Abhishek Dubey <adubey at linux.ibm.com>
> Co-developed-by: Madhavan Srinivasan <maddy at linux.ibm.com>
> Signed-off-by: Madhavan Srinivasan <maddy at linux.ibm.com>
> —

Here we can add the changelog.

With that change,
Reviewed-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>

Thanks
Athira
> arch/powerpc/platforms/pseries/Kconfig   |   9 ++
> arch/powerpc/platforms/pseries/Makefile  |   1 +
> arch/powerpc/platforms/pseries/htmdump.c | 121 +++++++++++++++++++++++
> 3 files changed, 131 insertions(+)
> create mode 100644 arch/powerpc/platforms/pseries/htmdump.c
> 
> diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
> index 42fc66e97539..b839e87408aa 100644
> --- a/arch/powerpc/platforms/pseries/Kconfig
> +++ b/arch/powerpc/platforms/pseries/Kconfig
> @@ -128,6 +128,15 @@ config CMM
>  will be reused for other LPARs. The interface allows firmware to
>  balance memory across many LPARs.
> 
> +config HTMDUMP
> + tristate "PowerVM data dumper"
> + depends on PPC_PSERIES && DEBUG_FS
> + default m
> + help
> +  Select this option, if you want to enable the kernel debugfs
> +  interface to dump the Hardware Trace Macro (HTM) function data
> +  in the LPAR.
> +
> config HV_PERF_CTRS
> bool "Hypervisor supplied PMU events (24x7 & GPCI)"
> default y
> diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
> index 7bf506f6b8c8..3f3e3492e436 100644
> --- a/arch/powerpc/platforms/pseries/Makefile
> +++ b/arch/powerpc/platforms/pseries/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_HVC_CONSOLE) += hvconsole.o
> obj-$(CONFIG_HVCS) += hvcserver.o
> obj-$(CONFIG_HCALL_STATS) += hvCall_inst.o
> obj-$(CONFIG_CMM) += cmm.o
> +obj-$(CONFIG_HTMDUMP) += htmdump.o
> obj-$(CONFIG_IO_EVENT_IRQ) += io_event_irq.o
> obj-$(CONFIG_LPARCFG) += lparcfg.o
> obj-$(CONFIG_IBMVIO) += vio.o
> diff --git a/arch/powerpc/platforms/pseries/htmdump.c b/arch/powerpc/platforms/pseries/htmdump.c
> new file mode 100644
> index 000000000000..57fc1700f604
> --- /dev/null
> +++ b/arch/powerpc/platforms/pseries/htmdump.c
> @@ -0,0 +1,121 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) IBM Corporation, 2024
> + */
> +
> +#define pr_fmt(fmt) "htmdump: " fmt
> +
> +#include <linux/debugfs.h>
> +#include <linux/module.h>
> +#include <asm/io.h>
> +#include <asm/machdep.h>
> +#include <asm/plpar_wrappers.h>
> +
> +static void *htm_buf;
> +static u32 nodeindex;
> +static u32 nodalchipindex;
> +static u32 coreindexonchip;
> +static u32 htmtype;
> +static struct dentry *htmdump_debugfs_dir;
> +
> +static ssize_t htmdump_read(struct file *filp, char __user *ubuf,
> +     size_t count, loff_t *ppos)
> +{
> + void *htm_buf = filp->private_data;
> + unsigned long page, read_size, available;
> + loff_t offset;
> + long rc;
> +
> + page = ALIGN_DOWN(*ppos, PAGE_SIZE);
> + offset = (*ppos) % PAGE_SIZE;
> +
> + rc = htm_get_dump_hardware(nodeindex, nodalchipindex, coreindexonchip,
> +   htmtype, virt_to_phys(htm_buf), PAGE_SIZE, page);
> +
> + switch (rc) {
> + case H_SUCCESS:
> + /* H_PARTIAL for the case where all available data can't be
> + * returned due to buffer size constraint.
> + */
> + case H_PARTIAL:
> + break;
> + /* H_NOT_AVAILABLE indicates reading from an offset outside the range,
> + * i.e. past end of file.
> + */
> + case H_NOT_AVAILABLE:
> + return 0;
> + case H_BUSY:
> + case H_LONG_BUSY_ORDER_1_MSEC:
> + case H_LONG_BUSY_ORDER_10_MSEC:
> + case H_LONG_BUSY_ORDER_100_MSEC:
> + case H_LONG_BUSY_ORDER_1_SEC:
> + case H_LONG_BUSY_ORDER_10_SEC:
> + case H_LONG_BUSY_ORDER_100_SEC:
> + return -EBUSY;
> + case H_PARAMETER:
> + case H_P2:
> + case H_P3:
> + case H_P4:
> + case H_P5:
> + case H_P6:
> + return -EINVAL;
> + case H_STATE:
> + return -EIO;
> + case H_AUTHORITY:
> + return -EPERM;
> + }
> +
> + available = PAGE_SIZE;
> + read_size = min(count, available);
> + *ppos += read_size;
> + return simple_read_from_buffer(ubuf, count, &offset, htm_buf, available);
> +}
> +
> +static const struct file_operations htmdump_fops = {
> + .llseek = NULL,
> + .read = htmdump_read,
> + .open = simple_open,
> +};
> +
> +static int htmdump_init_debugfs(void)
> +{
> + htm_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
> + if (!htm_buf) {
> + pr_err("Failed to allocate htmdump buf\n");
> + return -ENOMEM;
> + }
> +
> + htmdump_debugfs_dir = debugfs_create_dir("htmdump",
> +  arch_debugfs_dir);
> +
> + debugfs_create_u32("nodeindex", 0600,
> + htmdump_debugfs_dir, &nodeindex);
> + debugfs_create_u32("nodalchipindex", 0600,
> + htmdump_debugfs_dir, &nodalchipindex);
> + debugfs_create_u32("coreindexonchip", 0600,
> + htmdump_debugfs_dir, &coreindexonchip);
> + debugfs_create_u32("htmtype", 0600,
> + htmdump_debugfs_dir, &htmtype);
> + debugfs_create_file("trace", 0400, htmdump_debugfs_dir, htm_buf, &htmdump_fops);
> +
> + return 0;
> +}
> +
> +static int __init htmdump_init(void)
> +{
> + if (htmdump_init_debugfs())
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static void __exit htmdump_exit(void)
> +{
> + debugfs_remove_recursive(htmdump_debugfs_dir);
> + kfree(htm_buf);
> +}
> +
> +module_init(htmdump_init);
> +module_exit(htmdump_exit);
> +MODULE_DESCRIPTION("PHYP Hardware Trace Macro (HTM) data dumper");
> +MODULE_LICENSE("GPL");
> -- 
> 2.39.3
> 