This is needed when we resume the old kernel from the "current" kernel. Note: when hv_synic_suspend() and hv_synic_resume() run, all the non-boot CPUs have been offlined, and interrupts are disabled on CPU0. Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> --- drivers/hv/vmbus_drv.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index ebd35fc..2ef375c 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -30,6 +30,7 @@ #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" @@ -2086,6 +2087,47 @@ static void hv_crash_handler(struct pt_regs *regs) 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; @@ -2116,6 +2158,8 @@ static int __init hv_acpi_init(void) hv_setup_kexec_handler(hv_kexec_handler); hv_setup_crash_handler(hv_crash_handler); + register_syscore_ops(&hv_synic_syscore_ops); + return 0; cleanup: @@ -2128,6 +2172,8 @@ static void __exit vmbus_exit(void) { int cpu; + unregister_syscore_ops(&hv_synic_syscore_ops); + hv_remove_kexec_handler(); hv_remove_crash_handler(); vmbus_connection.conn_state = DISCONNECTED; -- 1.8.3.1