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

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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@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Dexuan Cui 2019-09-05 23:01:16 +00:00 committed by Sasha Levin
parent dba61cda30
commit 63ecc6d22c
1 changed files with 46 additions and 0 deletions
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46
drivers/hv/vmbus_drv.c
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@ -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;