On Wed, Sep 23, 2009 at 05:29:01PM -1000, Zachary Amsden wrote: > They are globals, not clearly protected by any ordering or locking, and > vulnerable to various startup races. > > Instead, for variable TSC machines, register the cpufreq notifier and get > the TSC frequency directly from the cpufreq machinery. Not only is it > always right, it is also perfectly accurate, as no error prone measurement > is required. On such machines, also detect the frequency when bringing > a new CPU online; it isn't clear what frequency it will start with, and > it may not correspond to the reference. > > Signed-off-by: Zachary Amsden <[email protected]> > --- > arch/x86/kvm/x86.c | 38 ++++++++++++++++++++++++++++---------- > 1 files changed, 28 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 15d2ace..35082dd 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -650,6 +650,19 @@ static void kvm_set_time_scale(uint32_t tsc_khz, struct > pvclock_vcpu_time_info * > > static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); > > +static inline void kvm_get_cpu_khz(int cpu) > +{ > + unsigned int khz = cpufreq_get(cpu);
cpufreq_get does down_read, while kvm_arch_hardware_enable is called either with a spinlock held or from interrupt context? -- 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
