5b02aa1e6e
When the initial domain starts, it prints (depending on the amount of CPUs) a slew of XENBUS: Unable to read cpu state XENBUS: Unable to read cpu state XENBUS: Unable to read cpu state XENBUS: Unable to read cpu state which provide no useful information - as the error is a valid issue - but not on the initial domain. The reason is that the XenStore is not accessible at that time (it is after all the first guest) so the CPU hotplug watch cannot parse "availability/cpu" attribute. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
113 lines
2 KiB
C
113 lines
2 KiB
C
#include <linux/notifier.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/cpu.h>
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static void enable_hotplug_cpu(int cpu)
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{
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if (!cpu_present(cpu))
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arch_register_cpu(cpu);
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set_cpu_present(cpu, true);
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}
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static void disable_hotplug_cpu(int cpu)
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{
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if (cpu_present(cpu))
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arch_unregister_cpu(cpu);
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set_cpu_present(cpu, false);
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}
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static int vcpu_online(unsigned int cpu)
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{
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int err;
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char dir[32], state[32];
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sprintf(dir, "cpu/%u", cpu);
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err = xenbus_scanf(XBT_NIL, dir, "availability", "%s", state);
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if (err != 1) {
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if (!xen_initial_domain())
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printk(KERN_ERR "XENBUS: Unable to read cpu state\n");
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return err;
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}
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if (strcmp(state, "online") == 0)
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return 1;
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else if (strcmp(state, "offline") == 0)
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return 0;
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printk(KERN_ERR "XENBUS: unknown state(%s) on CPU%d\n", state, cpu);
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return -EINVAL;
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}
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static void vcpu_hotplug(unsigned int cpu)
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{
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if (!cpu_possible(cpu))
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return;
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switch (vcpu_online(cpu)) {
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case 1:
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enable_hotplug_cpu(cpu);
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break;
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case 0:
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(void)cpu_down(cpu);
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disable_hotplug_cpu(cpu);
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break;
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default:
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break;
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}
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}
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static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
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const char **vec, unsigned int len)
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{
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unsigned int cpu;
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char *cpustr;
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const char *node = vec[XS_WATCH_PATH];
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cpustr = strstr(node, "cpu/");
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if (cpustr != NULL) {
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sscanf(cpustr, "cpu/%u", &cpu);
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vcpu_hotplug(cpu);
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}
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}
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static int setup_cpu_watcher(struct notifier_block *notifier,
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unsigned long event, void *data)
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{
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int cpu;
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static struct xenbus_watch cpu_watch = {
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.node = "cpu",
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.callback = handle_vcpu_hotplug_event};
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(void)register_xenbus_watch(&cpu_watch);
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for_each_possible_cpu(cpu) {
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if (vcpu_online(cpu) == 0) {
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(void)cpu_down(cpu);
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set_cpu_present(cpu, false);
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}
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}
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return NOTIFY_DONE;
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}
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static int __init setup_vcpu_hotplug_event(void)
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{
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static struct notifier_block xsn_cpu = {
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.notifier_call = setup_cpu_watcher };
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if (!xen_pv_domain())
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return -ENODEV;
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register_xenstore_notifier(&xsn_cpu);
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return 0;
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}
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arch_initcall(setup_vcpu_hotplug_event);
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