1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun #include <linux/notifier.h>
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun #include <xen/xen.h>
7*4882a593Smuzhiyun #include <xen/xenbus.h>
8*4882a593Smuzhiyun
9*4882a593Smuzhiyun #include <asm/xen/hypervisor.h>
10*4882a593Smuzhiyun #include <asm/cpu.h>
11*4882a593Smuzhiyun
enable_hotplug_cpu(int cpu)12*4882a593Smuzhiyun static void enable_hotplug_cpu(int cpu)
13*4882a593Smuzhiyun {
14*4882a593Smuzhiyun if (!cpu_present(cpu))
15*4882a593Smuzhiyun xen_arch_register_cpu(cpu);
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun set_cpu_present(cpu, true);
18*4882a593Smuzhiyun }
19*4882a593Smuzhiyun
disable_hotplug_cpu(int cpu)20*4882a593Smuzhiyun static void disable_hotplug_cpu(int cpu)
21*4882a593Smuzhiyun {
22*4882a593Smuzhiyun if (!cpu_is_hotpluggable(cpu))
23*4882a593Smuzhiyun return;
24*4882a593Smuzhiyun lock_device_hotplug();
25*4882a593Smuzhiyun if (cpu_online(cpu))
26*4882a593Smuzhiyun device_offline(get_cpu_device(cpu));
27*4882a593Smuzhiyun if (!cpu_online(cpu) && cpu_present(cpu)) {
28*4882a593Smuzhiyun xen_arch_unregister_cpu(cpu);
29*4882a593Smuzhiyun set_cpu_present(cpu, false);
30*4882a593Smuzhiyun }
31*4882a593Smuzhiyun unlock_device_hotplug();
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun
vcpu_online(unsigned int cpu)34*4882a593Smuzhiyun static int vcpu_online(unsigned int cpu)
35*4882a593Smuzhiyun {
36*4882a593Smuzhiyun int err;
37*4882a593Smuzhiyun char dir[16], state[16];
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun sprintf(dir, "cpu/%u", cpu);
40*4882a593Smuzhiyun err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state);
41*4882a593Smuzhiyun if (err != 1) {
42*4882a593Smuzhiyun if (!xen_initial_domain())
43*4882a593Smuzhiyun pr_err("Unable to read cpu state\n");
44*4882a593Smuzhiyun return err;
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun if (strcmp(state, "online") == 0)
48*4882a593Smuzhiyun return 1;
49*4882a593Smuzhiyun else if (strcmp(state, "offline") == 0)
50*4882a593Smuzhiyun return 0;
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun pr_err("unknown state(%s) on CPU%d\n", state, cpu);
53*4882a593Smuzhiyun return -EINVAL;
54*4882a593Smuzhiyun }
vcpu_hotplug(unsigned int cpu)55*4882a593Smuzhiyun static void vcpu_hotplug(unsigned int cpu)
56*4882a593Smuzhiyun {
57*4882a593Smuzhiyun if (cpu >= nr_cpu_ids || !cpu_possible(cpu))
58*4882a593Smuzhiyun return;
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun switch (vcpu_online(cpu)) {
61*4882a593Smuzhiyun case 1:
62*4882a593Smuzhiyun enable_hotplug_cpu(cpu);
63*4882a593Smuzhiyun break;
64*4882a593Smuzhiyun case 0:
65*4882a593Smuzhiyun disable_hotplug_cpu(cpu);
66*4882a593Smuzhiyun break;
67*4882a593Smuzhiyun default:
68*4882a593Smuzhiyun break;
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun }
71*4882a593Smuzhiyun
handle_vcpu_hotplug_event(struct xenbus_watch * watch,const char * path,const char * token)72*4882a593Smuzhiyun static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
73*4882a593Smuzhiyun const char *path, const char *token)
74*4882a593Smuzhiyun {
75*4882a593Smuzhiyun unsigned int cpu;
76*4882a593Smuzhiyun char *cpustr;
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun cpustr = strstr(path, "cpu/");
79*4882a593Smuzhiyun if (cpustr != NULL) {
80*4882a593Smuzhiyun sscanf(cpustr, "cpu/%u", &cpu);
81*4882a593Smuzhiyun vcpu_hotplug(cpu);
82*4882a593Smuzhiyun }
83*4882a593Smuzhiyun }
84*4882a593Smuzhiyun
setup_cpu_watcher(struct notifier_block * notifier,unsigned long event,void * data)85*4882a593Smuzhiyun static int setup_cpu_watcher(struct notifier_block *notifier,
86*4882a593Smuzhiyun unsigned long event, void *data)
87*4882a593Smuzhiyun {
88*4882a593Smuzhiyun int cpu;
89*4882a593Smuzhiyun static struct xenbus_watch cpu_watch = {
90*4882a593Smuzhiyun .node = "cpu",
91*4882a593Smuzhiyun .callback = handle_vcpu_hotplug_event};
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun (void)register_xenbus_watch(&cpu_watch);
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun for_each_possible_cpu(cpu) {
96*4882a593Smuzhiyun if (vcpu_online(cpu) == 0)
97*4882a593Smuzhiyun disable_hotplug_cpu(cpu);
98*4882a593Smuzhiyun }
99*4882a593Smuzhiyun
100*4882a593Smuzhiyun return NOTIFY_DONE;
101*4882a593Smuzhiyun }
102*4882a593Smuzhiyun
setup_vcpu_hotplug_event(void)103*4882a593Smuzhiyun static int __init setup_vcpu_hotplug_event(void)
104*4882a593Smuzhiyun {
105*4882a593Smuzhiyun static struct notifier_block xsn_cpu = {
106*4882a593Smuzhiyun .notifier_call = setup_cpu_watcher };
107*4882a593Smuzhiyun
108*4882a593Smuzhiyun #ifdef CONFIG_X86
109*4882a593Smuzhiyun if (!xen_pv_domain() && !xen_pvh_domain())
110*4882a593Smuzhiyun #else
111*4882a593Smuzhiyun if (!xen_domain())
112*4882a593Smuzhiyun #endif
113*4882a593Smuzhiyun return -ENODEV;
114*4882a593Smuzhiyun
115*4882a593Smuzhiyun register_xenstore_notifier(&xsn_cpu);
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun return 0;
118*4882a593Smuzhiyun }
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun late_initcall(setup_vcpu_hotplug_event);
121*4882a593Smuzhiyun
122