[PATCH AUTOSEL 4.19 091/237] powerpc/pseries: Export raw per-CPU VPA data via debugfs

Sasha Levin
2019-11-16T16:22:52Z

From: Aravinda Prasad <aravinda@linux.vnet.ibm.com>

[ Upstream commit c6c26fb55e8e4b3fc376be5611685990a17de27a ]

This patch exports the raw per-CPU VPA data via debugfs.
A per-CPU file is created which exports the VPA data of
that CPU to help debug some of the VPA related issues or
to analyze the per-CPU VPA related statistics.

v3: Removed offline CPU check.

v2: Included offline CPU check and other review comments.

Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/platforms/pseries/lpar.c | 54 +++++++++++++++++++++++++++
1 file changed, 54 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index ea602f7f97ce1..49e3a88b6a0c1 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -48,6 +48,7 @@
#include <asm/kexec.h>
#include <asm/fadump.h>
#include <asm/asm-prototypes.h>
+#include <asm/debugfs.h>

#include "pseries.h"

@@ -1032,3 +1033,56 @@ static int __init reserve_vrma_context_id(void)
return 0;
}
machine_device_initcall(pseries, reserve_vrma_context_id);
+
+#ifdef CONFIG_DEBUG_FS
+/* debugfs file interface for vpa data */
+static ssize_t vpa_file_read(struct file *filp, char __user *buf, size_t len,
+ loff_t *pos)
+{
+ int cpu = (long)filp->private_data;
+ struct lppaca *lppaca = &lppaca_of(cpu);
+
+ return simple_read_from_buffer(buf, len, pos, lppaca,
+ sizeof(struct lppaca));
+}
+
+static const struct file_operations vpa_fops = {
+ .open = simple_open,
+ .read = vpa_file_read,
+ .llseek = default_llseek,
+};
+
+static int __init vpa_debugfs_init(void)
+{
+ char name[16];
+ long i;
+ static struct dentry *vpa_dir;
+
+ if (!firmware_has_feature(FW_FEATURE_SPLPAR))
+ return 0;
+
+ vpa_dir = debugfs_create_dir("vpa", powerpc_debugfs_root);
+ if (!vpa_dir) {
+ pr_warn("%s: can't create vpa root dir\n", __func__);
+ return -ENOMEM;
+ }
+
+ /* set up the per-cpu vpa file*/
+ for_each_possible_cpu(i) {
+ struct dentry *d;
+
+ sprintf(name, "cpu-%ld", i);
+
+ d = debugfs_create_file(name, 0400, vpa_dir, (void *)i,
+ &vpa_fops);
+ if (!d) {
+ pr_warn("%s: can't create per-cpu vpa file\n",
+ __func__);
+ return -ENOMEM;
+ }
+ }
+
+ return 0;
+}
+machine_arch_initcall(pseries, vpa_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */
--
2.20.1