Drivers: hv: vmbus: Suspend/resume the synic for hibernation

#include <linux/kdebug.h>

#include <linux/efi.h>

#include <linux/random.h>

#include <linux/syscore_ops.h>

#include <clocksource/hyperv_timer.h>

#include "hyperv_vmbus.h"

	hyperv_cleanup();

};

static int hv_synic_suspend(void)

{

	/*

	 * When we reach here, all the non-boot CPUs have been offlined, and

	 * the stimers on them have been unbound in hv_synic_cleanup() ->

	 * hv_stimer_cleanup() -> clockevents_unbind_device().

	 *

	 * hv_synic_suspend() only runs on CPU0 with interrupts disabled. Here

	 * we do not unbind the stimer on CPU0 because: 1) it's unnecessary

	 * because the interrupts remain disabled between syscore_suspend()

	 * and syscore_resume(): see create_image() and resume_target_kernel();

	 * 2) the stimer on CPU0 is automatically disabled later by

	 * syscore_suspend() -> timekeeping_suspend() -> tick_suspend() -> ...

	 * -> clockevents_shutdown() -> ... -> hv_ce_shutdown(); 3) a warning

	 * would be triggered if we call clockevents_unbind_device(), which

	 * may sleep, in an interrupts-disabled context. So, we intentionally

	 * don't call hv_stimer_cleanup(0) here.

	 */

	hv_synic_disable_regs(0);

	return 0;

}

static void hv_synic_resume(void)

{

	hv_synic_enable_regs(0);

	/*

	 * Note: we don't need to call hv_stimer_init(0), because the timer

	 * on CPU0 is not unbound in hv_synic_suspend(), and the timer is

	 * automatically re-enabled in timekeeping_resume().

	 */

}

/* The callbacks run only on CPU0, with irqs_disabled. */

static struct syscore_ops hv_synic_syscore_ops = {

	.suspend = hv_synic_suspend,

	.resume = hv_synic_resume,

};

static int __init hv_acpi_init(void)

{

	int ret, t;

	hv_setup_kexec_handler(hv_kexec_handler);

	hv_setup_crash_handler(hv_crash_handler);

	register_syscore_ops(&hv_synic_syscore_ops);

	return 0;

cleanup:

{

	int cpu;

	unregister_syscore_ops(&hv_synic_syscore_ops);

	hv_remove_kexec_handler();

	hv_remove_crash_handler();

	vmbus_connection.conn_state = DISCONNECTED;