> +static unsigned int ref_freq;
> +static unsigned long loops_per_jiffy_ref;
> +static unsigned long tsc_khz_ref;
Doesn't these need to be percpu too ?
Otherwise we could be calculating the new frequency based on a foreign
reference.
> +
> +static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
> + void *data)
> +{
> + struct cpufreq_freqs *freq = data;
> + unsigned long *lpj, dummy;
> + struct kvm *kvm;
> + struct kvm_vcpu *vcpu;
> + int i, guest_mode;
> +
> + if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC))
> + return 0;
> +
> + lpj = &dummy;
> + if (!(freq->flags & CPUFREQ_CONST_LOOPS))
> +#ifdef CONFIG_SMP
> + lpj = &cpu_data(freq->cpu).loops_per_jiffy;
> +#else
> + lpj = &boot_cpu_data.loops_per_jiffy;
> +#endif
> +
> + if (!ref_freq) {
> + ref_freq = freq->old;
> + loops_per_jiffy_ref = *lpj;
> + tsc_khz_ref = tsc_khz;
> + }
> +
> + if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
> + (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
> + (val == CPUFREQ_RESUMECHANGE)) {
> + *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
> + per_cpu(cpu_tsc_khz, freq->cpu) = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
I believe a possible approach is to move those that refer to tsc
calculation to tsc.c, and make all uses
of tsc_khz comply to a per_cpu use. A global tsc_khz does not make sense anyway.
Then we'll have a specific kvm notifier that just forces the guest out
of its execution so we can update
the clock state.
--
Glauber Costa.
"Free as in Freedom"
http://glommer.net
"The less confident you are, the more serious you have to act."
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