tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
kvm powerpc/book3s-apiv2: Introduce kvm-hv specific PMU
Introduce a new PMU named 'kvm-hv' inside a new module named 'kvm-hv-pmu'
to report Book3s kvm-hv specific performance counters. This will expose
KVM-HV specific performance attributes to user-space via kernel's PMU
infrastructure and would enableusers to monitor active kvm-hv based guests.
The patch creates necessary scaffolding to for the new PMU callbacks and
introduces the new kernel module name 'kvm-hv-pmu' which is built with
CONFIG_KVM_BOOK3S_HV_PMU. The patch doesn't introduce any perf-events yet,
which will be introduced in later patches
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250416162740.93143-5-vaibhav@linux.ibm.com
authored by
Vaibhav Jain
and committed by
Madhavan Srinivasan
ff45bf50
1f35ad2b
+153
+13
arch/powerpc/kvm/Kconfig
+13
arch/powerpc/kvm/Kconfig
···
83
83
depends on KVM_BOOK3S_64 && PPC_POWERNV
84
84
select KVM_BOOK3S_HV_POSSIBLE
85
85
select KVM_GENERIC_MMU_NOTIFIER
86
+
select KVM_BOOK3S_HV_PMU
86
87
select CMA
87
88
help
88
89
Support running unmodified book3s_64 guest kernels in
···
171
170
Selecting this option for the L0 host implements a workaround for
172
171
those buggy L1s which saves the L2 state, at the cost of performance
173
172
in all nested-capable guest entry/exit.
173
+
174
+
config KVM_BOOK3S_HV_PMU
175
+
tristate "Hypervisor Perf events for KVM Book3s-HV"
176
+
depends on KVM_BOOK3S_64_HV
177
+
help
178
+
Enable Book3s-HV Hypervisor Perf events PMU named 'kvm-hv'. These
179
+
Perf events give an overview of hypervisor performance overall
180
+
instead of a specific guests. Currently the PMU reports
181
+
L0-Hypervisor stats on a kvm-hv enabled PSeries LPAR like:
182
+
* Total/Used Guest-Heap
183
+
* Total/Used Guest Page-table Memory
184
+
* Total amount of Guest Page-table Memory reclaimed
174
185
175
186
config KVM_BOOKE_HV
176
187
bool
+2
arch/powerpc/perf/Makefile
+2
arch/powerpc/perf/Makefile
+138
arch/powerpc/perf/kvm-hv-pmu.c
+138
arch/powerpc/perf/kvm-hv-pmu.c
···
1
+
// SPDX-License-Identifier: GPL-2.0
2
+
/*
3
+
* Description: PMUs specific to running nested KVM-HV guests
4
+
* on Book3S processors (specifically POWER9 and later).
5
+
*/
6
+
7
+
#define pr_fmt(fmt) "kvmppc-pmu: " fmt
8
+
9
+
#include "asm-generic/local64.h"
10
+
#include <linux/kernel.h>
11
+
#include <linux/errno.h>
12
+
#include <linux/ratelimit.h>
13
+
#include <linux/kvm_host.h>
14
+
#include <linux/gfp_types.h>
15
+
#include <linux/pgtable.h>
16
+
#include <linux/perf_event.h>
17
+
#include <linux/spinlock_types.h>
18
+
#include <linux/spinlock.h>
19
+
20
+
#include <asm/types.h>
21
+
#include <asm/kvm_ppc.h>
22
+
#include <asm/kvm_book3s.h>
23
+
#include <asm/mmu.h>
24
+
#include <asm/pgalloc.h>
25
+
#include <asm/pte-walk.h>
26
+
#include <asm/reg.h>
27
+
#include <asm/plpar_wrappers.h>
28
+
#include <asm/firmware.h>
29
+
30
+
enum kvmppc_pmu_eventid {
31
+
KVMPPC_EVENT_MAX,
32
+
};
33
+
34
+
static struct attribute *kvmppc_pmu_events_attr[] = {
35
+
NULL,
36
+
};
37
+
38
+
static const struct attribute_group kvmppc_pmu_events_group = {
39
+
.name = "events",
40
+
.attrs = kvmppc_pmu_events_attr,
41
+
};
42
+
43
+
PMU_FORMAT_ATTR(event, "config:0");
44
+
static struct attribute *kvmppc_pmu_format_attr[] = {
45
+
&format_attr_event.attr,
46
+
NULL,
47
+
};
48
+
49
+
static struct attribute_group kvmppc_pmu_format_group = {
50
+
.name = "format",
51
+
.attrs = kvmppc_pmu_format_attr,
52
+
};
53
+
54
+
static const struct attribute_group *kvmppc_pmu_attr_groups[] = {
55
+
&kvmppc_pmu_events_group,
56
+
&kvmppc_pmu_format_group,
57
+
NULL,
58
+
};
59
+
60
+
static int kvmppc_pmu_event_init(struct perf_event *event)
61
+
{
62
+
unsigned int config = event->attr.config;
63
+
64
+
pr_debug("%s: Event(%p) id=%llu cpu=%x on_cpu=%x config=%u",
65
+
__func__, event, event->id, event->cpu,
66
+
event->oncpu, config);
67
+
68
+
if (event->attr.type != event->pmu->type)
69
+
return -ENOENT;
70
+
71
+
if (config >= KVMPPC_EVENT_MAX)
72
+
return -EINVAL;
73
+
74
+
local64_set(&event->hw.prev_count, 0);
75
+
local64_set(&event->count, 0);
76
+
77
+
return 0;
78
+
}
79
+
80
+
static void kvmppc_pmu_del(struct perf_event *event, int flags)
81
+
{
82
+
}
83
+
84
+
static int kvmppc_pmu_add(struct perf_event *event, int flags)
85
+
{
86
+
return 0;
87
+
}
88
+
89
+
static void kvmppc_pmu_read(struct perf_event *event)
90
+
{
91
+
}
92
+
93
+
/* L1 wide counters PMU */
94
+
static struct pmu kvmppc_pmu = {
95
+
.module = THIS_MODULE,
96
+
.task_ctx_nr = perf_sw_context,
97
+
.name = "kvm-hv",
98
+
.event_init = kvmppc_pmu_event_init,
99
+
.add = kvmppc_pmu_add,
100
+
.del = kvmppc_pmu_del,
101
+
.read = kvmppc_pmu_read,
102
+
.attr_groups = kvmppc_pmu_attr_groups,
103
+
.type = -1,
104
+
};
105
+
106
+
static int __init kvmppc_register_pmu(void)
107
+
{
108
+
int rc = -EOPNOTSUPP;
109
+
110
+
/* only support events for nestedv2 right now */
111
+
if (kvmhv_is_nestedv2()) {
112
+
/* Register the pmu */
113
+
rc = perf_pmu_register(&kvmppc_pmu, kvmppc_pmu.name, -1);
114
+
if (rc)
115
+
goto out;
116
+
117
+
pr_info("Registered kvm-hv pmu");
118
+
}
119
+
120
+
out:
121
+
return rc;
122
+
}
123
+
124
+
static void __exit kvmppc_unregister_pmu(void)
125
+
{
126
+
if (kvmhv_is_nestedv2()) {
127
+
if (kvmppc_pmu.type != -1)
128
+
perf_pmu_unregister(&kvmppc_pmu);
129
+
130
+
pr_info("kvmhv_pmu unregistered.\n");
131
+
}
132
+
}
133
+
134
+
module_init(kvmppc_register_pmu);
135
+
module_exit(kvmppc_unregister_pmu);
136
+
MODULE_DESCRIPTION("KVM PPC Book3s-hv PMU");
137
+
MODULE_AUTHOR("Vaibhav Jain <vaibhav@linux.ibm.com>");
138
+
MODULE_LICENSE("GPL");