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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Xen stolen ticks accounting.
4 */
5#include <linux/kernel.h>
6#include <linux/kernel_stat.h>
7#include <linux/math64.h>
8#include <linux/gfp.h>
9#include <linux/slab.h>
10#include <linux/static_call.h>
11
12#include <asm/paravirt.h>
13#include <asm/xen/hypervisor.h>
14#include <asm/xen/hypercall.h>
15
16#include <xen/events.h>
17#include <xen/features.h>
18#include <xen/interface/xen.h>
19#include <xen/interface/vcpu.h>
20#include <xen/xen-ops.h>
21
22/* runstate info updated by Xen */
23static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
24
25static DEFINE_PER_CPU(u64[4], old_runstate_time);
26
27/* return an consistent snapshot of 64-bit time/counter value */
28static u64 get64(const u64 *p)
29{
30 u64 ret;
31
32 if (BITS_PER_LONG < 64) {
33 u32 *p32 = (u32 *)p;
34 u32 h, l, h2;
35
36 /*
37 * Read high then low, and then make sure high is
38 * still the same; this will only loop if low wraps
39 * and carries into high.
40 * XXX some clean way to make this endian-proof?
41 */
42 do {
43 h = READ_ONCE(p32[1]);
44 l = READ_ONCE(p32[0]);
45 h2 = READ_ONCE(p32[1]);
46 } while(h2 != h);
47
48 ret = (((u64)h) << 32) | l;
49 } else
50 ret = READ_ONCE(*p);
51
52 return ret;
53}
54
55static void xen_get_runstate_snapshot_cpu_delta(
56 struct vcpu_runstate_info *res, unsigned int cpu)
57{
58 u64 state_time;
59 struct vcpu_runstate_info *state;
60
61 BUG_ON(preemptible());
62
63 state = per_cpu_ptr(&xen_runstate, cpu);
64
65 do {
66 state_time = get64(&state->state_entry_time);
67 rmb(); /* Hypervisor might update data. */
68 *res = __READ_ONCE(*state);
69 rmb(); /* Hypervisor might update data. */
70 } while (get64(&state->state_entry_time) != state_time ||
71 (state_time & XEN_RUNSTATE_UPDATE));
72}
73
74static void xen_get_runstate_snapshot_cpu(struct vcpu_runstate_info *res,
75 unsigned int cpu)
76{
77 int i;
78
79 xen_get_runstate_snapshot_cpu_delta(res, cpu);
80
81 for (i = 0; i < 4; i++)
82 res->time[i] += per_cpu(old_runstate_time, cpu)[i];
83}
84
85void xen_manage_runstate_time(int action)
86{
87 static struct vcpu_runstate_info *runstate_delta;
88 struct vcpu_runstate_info state;
89 int cpu, i;
90
91 switch (action) {
92 case -1: /* backup runstate time before suspend */
93 if (unlikely(runstate_delta))
94 pr_warn_once("%s: memory leak as runstate_delta is not NULL\n",
95 __func__);
96
97 runstate_delta = kmalloc_array(num_possible_cpus(),
98 sizeof(*runstate_delta),
99 GFP_ATOMIC);
100 if (unlikely(!runstate_delta)) {
101 pr_warn("%s: failed to allocate runstate_delta\n",
102 __func__);
103 return;
104 }
105
106 for_each_possible_cpu(cpu) {
107 xen_get_runstate_snapshot_cpu_delta(&state, cpu);
108 memcpy(runstate_delta[cpu].time, state.time,
109 sizeof(runstate_delta[cpu].time));
110 }
111
112 break;
113
114 case 0: /* backup runstate time after resume */
115 if (unlikely(!runstate_delta)) {
116 pr_warn("%s: cannot accumulate runstate time as runstate_delta is NULL\n",
117 __func__);
118 return;
119 }
120
121 for_each_possible_cpu(cpu) {
122 for (i = 0; i < 4; i++)
123 per_cpu(old_runstate_time, cpu)[i] +=
124 runstate_delta[cpu].time[i];
125 }
126
127 break;
128
129 default: /* do not accumulate runstate time for checkpointing */
130 break;
131 }
132
133 if (action != -1 && runstate_delta) {
134 kfree(runstate_delta);
135 runstate_delta = NULL;
136 }
137}
138
139/*
140 * Runstate accounting
141 */
142void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
143{
144 xen_get_runstate_snapshot_cpu(res, smp_processor_id());
145}
146
147/* return true when a vcpu could run but has no real cpu to run on */
148bool xen_vcpu_stolen(int vcpu)
149{
150 return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
151}
152
153u64 xen_steal_clock(int cpu)
154{
155 struct vcpu_runstate_info state;
156
157 xen_get_runstate_snapshot_cpu(&state, cpu);
158 return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];
159}
160
161void xen_setup_runstate_info(int cpu)
162{
163 struct vcpu_register_runstate_memory_area area;
164
165 area.addr.v = &per_cpu(xen_runstate, cpu);
166
167 if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
168 xen_vcpu_nr(cpu), &area))
169 BUG();
170}
171
172void __init xen_time_setup_guest(void)
173{
174 bool xen_runstate_remote;
175
176 xen_runstate_remote = !HYPERVISOR_vm_assist(VMASST_CMD_enable,
177 VMASST_TYPE_runstate_update_flag);
178
179 static_call_update(pv_steal_clock, xen_steal_clock);
180
181 static_key_slow_inc(¶virt_steal_enabled);
182 if (xen_runstate_remote)
183 static_key_slow_inc(¶virt_steal_rq_enabled);
184}
1/*
2 * Xen stolen ticks accounting.
3 */
4#include <linux/kernel.h>
5#include <linux/kernel_stat.h>
6#include <linux/math64.h>
7#include <linux/gfp.h>
8
9#include <asm/paravirt.h>
10#include <asm/xen/hypervisor.h>
11#include <asm/xen/hypercall.h>
12
13#include <xen/events.h>
14#include <xen/features.h>
15#include <xen/interface/xen.h>
16#include <xen/interface/vcpu.h>
17#include <xen/xen-ops.h>
18
19/* runstate info updated by Xen */
20static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
21
22/* return an consistent snapshot of 64-bit time/counter value */
23static u64 get64(const u64 *p)
24{
25 u64 ret;
26
27 if (BITS_PER_LONG < 64) {
28 u32 *p32 = (u32 *)p;
29 u32 h, l, h2;
30
31 /*
32 * Read high then low, and then make sure high is
33 * still the same; this will only loop if low wraps
34 * and carries into high.
35 * XXX some clean way to make this endian-proof?
36 */
37 do {
38 h = READ_ONCE(p32[1]);
39 l = READ_ONCE(p32[0]);
40 h2 = READ_ONCE(p32[1]);
41 } while(h2 != h);
42
43 ret = (((u64)h) << 32) | l;
44 } else
45 ret = READ_ONCE(*p);
46
47 return ret;
48}
49
50static void xen_get_runstate_snapshot_cpu(struct vcpu_runstate_info *res,
51 unsigned int cpu)
52{
53 u64 state_time;
54 struct vcpu_runstate_info *state;
55
56 BUG_ON(preemptible());
57
58 state = per_cpu_ptr(&xen_runstate, cpu);
59
60 do {
61 state_time = get64(&state->state_entry_time);
62 rmb(); /* Hypervisor might update data. */
63 *res = READ_ONCE(*state);
64 rmb(); /* Hypervisor might update data. */
65 } while (get64(&state->state_entry_time) != state_time ||
66 (state_time & XEN_RUNSTATE_UPDATE));
67}
68
69/*
70 * Runstate accounting
71 */
72void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
73{
74 xen_get_runstate_snapshot_cpu(res, smp_processor_id());
75}
76
77/* return true when a vcpu could run but has no real cpu to run on */
78bool xen_vcpu_stolen(int vcpu)
79{
80 return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
81}
82
83u64 xen_steal_clock(int cpu)
84{
85 struct vcpu_runstate_info state;
86
87 xen_get_runstate_snapshot_cpu(&state, cpu);
88 return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];
89}
90
91void xen_setup_runstate_info(int cpu)
92{
93 struct vcpu_register_runstate_memory_area area;
94
95 area.addr.v = &per_cpu(xen_runstate, cpu);
96
97 if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
98 xen_vcpu_nr(cpu), &area))
99 BUG();
100}
101
102void __init xen_time_setup_guest(void)
103{
104 bool xen_runstate_remote;
105
106 xen_runstate_remote = !HYPERVISOR_vm_assist(VMASST_CMD_enable,
107 VMASST_TYPE_runstate_update_flag);
108
109 pv_time_ops.steal_clock = xen_steal_clock;
110
111 static_key_slow_inc(¶virt_steal_enabled);
112 if (xen_runstate_remote)
113 static_key_slow_inc(¶virt_steal_rq_enabled);
114}