diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/kvmclock.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index b999f5e5b3bf..ddee04043aeb 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -22,6 +22,7 @@ #include <asm/msr.h> #include <asm/apic.h> #include <linux/percpu.h> +#include <asm/reboot.h> #define KVM_SCALE 22 @@ -143,6 +144,28 @@ static void kvm_setup_secondary_clock(void) setup_secondary_APIC_clock(); } +/* + * After the clock is registered, the host will keep writing to the + * registered memory location. If the guest happens to shutdown, this memory + * won't be valid. In cases like kexec, in which you install a new kernel, this + * means a random memory location will be kept being written. So before any + * kind of shutdown from our side, we unregister the clock by writting anything + * that does not have the 'enable' bit set in the msr + */ +#ifdef CONFIG_KEXEC +static void kvm_crash_shutdown(struct pt_regs *regs) +{ + native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); + native_machine_crash_shutdown(regs); +} +#endif + +static void kvm_shutdown(void) +{ + native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0); + native_machine_shutdown(); +} + void __init kvmclock_init(void) { if (!kvm_para_available()) @@ -155,6 +178,10 @@ void __init kvmclock_init(void) pv_time_ops.set_wallclock = kvm_set_wallclock; pv_time_ops.sched_clock = kvm_clock_read; pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock; + machine_ops.shutdown = kvm_shutdown; +#ifdef CONFIG_KEXEC + machine_ops.crash_shutdown = kvm_crash_shutdown; +#endif clocksource_register(&kvm_clock); } } |