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" introduced 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:
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-ma...@linux.ibm.com/
Signed-off-by: Abhishek Dubey <adu...@linux.ibm.com>
Co-developed-by: Madhavan Srinivasan <ma...@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <ma...@linux.ibm.com>
---
arch/powerpc/platforms/pseries/Kconfig | 9 ++
arch/powerpc/platforms/pseries/Makefile | 1 +
arch/powerpc/platforms/pseries/htmdump.c | 120 +++++++++++++++++++++++
3 files changed, 130 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 afc0f6a61337..e0fcd4bef986 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..9ba0507e54d7
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/htmdump.c
@@ -0,0 +1,120 @@
+// 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/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");
--
2.44.0
