On 11/07/2016 14:28, Anna-Maria Gleixner wrote:
> From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
>
> Install the callbacks via the state machine and let the core invoke
> the callbacks on the already online CPUs.
>
> We assumed that the priority ordering was ment to invoke the online
> callback as the last step. In the original code this also invoked the
> down prepare callback as the last step. With the symmetric state
> machine the down prepare callback is now the first step.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Gleb Natapov <gleb@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 35 ++++++++---------------------------
> include/linux/cpuhotplug.h | 1 +
> 2 files changed, 9 insertions(+), 27 deletions(-)
>
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5552,9 +5552,10 @@ int kvm_fast_pio_out(struct kvm_vcpu *vc
> }
> EXPORT_SYMBOL_GPL(kvm_fast_pio_out);
>
> -static void tsc_bad(void *info)
> +static int kvmclock_cpu_down_prep(unsigned int cpu)
> {
> __this_cpu_write(cpu_tsc_khz, 0);
> + return 0;
> }
>
> static void tsc_khz_changed(void *data)
> @@ -5659,35 +5660,18 @@ static struct notifier_block kvmclock_cp
> .notifier_call = kvmclock_cpufreq_notifier
> };
>
> -static int kvmclock_cpu_notifier(struct notifier_block *nfb,
> - unsigned long action, void *hcpu)
> +static int kvmclock_cpu_online(unsigned int cpu)
> {
> - unsigned int cpu = (unsigned long)hcpu;
> -
> - switch (action) {
> - case CPU_ONLINE:
> - case CPU_DOWN_FAILED:
> - tsc_khz_changed(NULL);
> - break;
> - case CPU_DOWN_PREPARE:
> - tsc_bad(NULL);
> - break;
> - }
> - return NOTIFY_OK;
> + tsc_khz_changed(NULL);
> + return 0;
> }
>
> -static struct notifier_block kvmclock_cpu_notifier_block = {
> - .notifier_call = kvmclock_cpu_notifier,
> - .priority = -INT_MAX
> -};
> -
> static void kvm_timer_init(void)
> {
> int cpu;
>
> max_tsc_khz = tsc_khz;
>
> - cpu_notifier_register_begin();
> if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
> #ifdef CONFIG_CPU_FREQ
> struct cpufreq_policy policy;
> @@ -5702,12 +5686,9 @@ static void kvm_timer_init(void)
> CPUFREQ_TRANSITION_NOTIFIER);
> }
> pr_debug("kvm: max_tsc_khz = %ld\n", max_tsc_khz);
> - for_each_online_cpu(cpu)
> - smp_call_function_single(cpu, tsc_khz_changed, NULL, 1);
> -
> - __register_hotcpu_notifier(&kvmclock_cpu_notifier_block);
> - cpu_notifier_register_done();
>
> + cpuhp_setup_state(CPUHP_AP_X86_KVM_CLK_ONLINE, "AP_X86_KVM_CLK_ONLINE",
> + kvmclock_cpu_online, kvmclock_cpu_down_prep);
> }
>
> static DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
> @@ -5896,7 +5877,7 @@ void kvm_arch_exit(void)
> if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
> cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
> CPUFREQ_TRANSITION_NOTIFIER);
> - unregister_hotcpu_notifier(&kvmclock_cpu_notifier_block);
> + cpuhp_remove_state_nocalls(CPUHP_X86_KVM_CLK_ONLINE);
> #ifdef CONFIG_X86_64
> pvclock_gtod_unregister_notifier(&pvclock_gtod_notifier);
> #endif
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -56,6 +56,7 @@ enum cpuhp_state {
> CPUHP_AP_ONLINE_DYN,
> CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,
> CPUHP_AP_X86_HPET_ONLINE,
> + CPUHP_AP_X86_KVM_CLK_ONLINE,
> CPUHP_AP_ACTIVE,
> CPUHP_ONLINE,
> };
>
>
>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
(I don't have problems with patches sent as attachments, but others might).
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