If !CONFIG_KVM_GUEST, kvm_smp_prepare_boot_cpu() is not defined. So,
kvm_register_clock("primary cpu clock") in kvm_smp_prepare_boot_cpu()
is not called.The detail of problem is hv_clock percpu usage. hv_clock is percpu variable, but kvmclock_init() is called _before_ initializing percpu area, and doesn't update address after initialized percpu area. So, host kvm modify the memory area _before_ initializing percpu. This became the cause of strange memory corruption on guest OS. This fixes it by adding kvm_smp_prepare_boot_cpu(). [we might be better to kill the usage before percpu initialization.] Signed-off-by: OGAWA Hirofumi <[email protected]> --- arch/x86/kernel/kvmclock.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff -puN arch/x86/kernel/kvmclock.c~kvm-fix-kvmclock-init arch/x86/kernel/kvmclock.c --- tux3fs/arch/x86/kernel/kvmclock.c~kvm-fix-kvmclock-init 2012-08-15 22:15:22.000000000 +0900 +++ tux3fs-hirofumi/arch/x86/kernel/kvmclock.c 2012-08-15 22:16:14.000000000 +0900 @@ -145,6 +145,14 @@ static void kvm_restore_sched_clock_stat kvm_register_clock("primary cpu clock, resume"); } +#if defined(CONFIG_SMP) && !defined(CONFIG_KVM_GUEST) +static void __init kvm_smp_prepare_boot_cpu(void) +{ + WARN_ON(kvm_register_clock("primary cpu clock")); + native_smp_prepare_boot_cpu(); +} +#endif + #ifdef CONFIG_X86_LOCAL_APIC static void __cpuinit kvm_setup_secondary_clock(void) { @@ -194,6 +202,12 @@ void __init kvmclock_init(void) printk(KERN_INFO "kvm-clock: Using msrs %x and %x", msr_kvm_system_time, msr_kvm_wall_clock); + /* + * This is temporary register until percpu is initialized. + * After percpu was initialized, we register real hv_clock via + * kvm_smp_prepare_boot_cpu(). + * FIXME: it wouldn't be good to use before percpu is initialized. + */ if (kvm_register_clock("boot clock")) return; pv_time_ops.sched_clock = kvm_clock_read; @@ -210,6 +224,9 @@ void __init kvmclock_init(void) #ifdef CONFIG_KEXEC machine_ops.crash_shutdown = kvm_crash_shutdown; #endif +#if defined(CONFIG_SMP) && !defined(CONFIG_KVM_GUEST) + smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; +#endif kvm_get_preset_lpj(); clocksource_register_hz(&kvm_clock, NSEC_PER_SEC); pv_info.paravirt_enabled = 1; _ -- OGAWA Hirofumi <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
