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| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-02-08 14:51:40 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-02-16 18:48:34 +0100 |
| commit | 78db6a5037965429c04d708281f35a6e5562d31b (patch) | |
| tree | 69df8a7348f8d7c2377a5b8acd3c9a46c156a14f | |
| parent | 4941b8cb3746f09bb102f7a5d64d878e96a0c6cd (diff) | |
| download | linux-78db6a5037965429c04d708281f35a6e5562d31b.tar.bz2 | |
KVM: x86: rewrite handling of scaled TSC for kvmclock
This is the same as before:
kvm_scale_tsc(tgt_tsc_khz)
= tgt_tsc_khz * ratio
= tgt_tsc_khz * user_tsc_khz / tsc_khz (see set_tsc_khz)
= user_tsc_khz (see kvm_guest_time_update)
= vcpu->arch.virtual_tsc_khz (see kvm_set_tsc_khz)
However, computing it through kvm_scale_tsc will make it possible
to include the NTP correction in tgt_tsc_khz.
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 16bbe6df679b..01d22b37556c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1713,7 +1713,7 @@ static void kvm_gen_update_masterclock(struct kvm *kvm) static int kvm_guest_time_update(struct kvm_vcpu *v) { - unsigned long flags, this_tsc_khz, tgt_tsc_khz; + unsigned long flags, tgt_tsc_khz; struct kvm_vcpu_arch *vcpu = &v->arch; struct kvm_arch *ka = &v->kvm->arch; s64 kernel_ns; @@ -1739,8 +1739,8 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) /* Keep irq disabled to prevent changes to the clock */ local_irq_save(flags); - this_tsc_khz = __this_cpu_read(cpu_tsc_khz); - if (unlikely(this_tsc_khz == 0)) { + tgt_tsc_khz = __this_cpu_read(cpu_tsc_khz); + if (unlikely(tgt_tsc_khz == 0)) { local_irq_restore(flags); kvm_make_request(KVM_REQ_CLOCK_UPDATE, v); return 1; @@ -1775,13 +1775,14 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) if (!vcpu->pv_time_enabled) return 0; - if (unlikely(vcpu->hw_tsc_khz != this_tsc_khz)) { - tgt_tsc_khz = kvm_has_tsc_control ? - vcpu->virtual_tsc_khz : this_tsc_khz; + if (kvm_has_tsc_control) + tgt_tsc_khz = kvm_scale_tsc(v, tgt_tsc_khz); + + if (unlikely(vcpu->hw_tsc_khz != tgt_tsc_khz)) { kvm_get_time_scale(NSEC_PER_SEC / 1000, tgt_tsc_khz, &vcpu->hv_clock.tsc_shift, &vcpu->hv_clock.tsc_to_system_mul); - vcpu->hw_tsc_khz = this_tsc_khz; + vcpu->hw_tsc_khz = tgt_tsc_khz; } /* With all the info we got, fill in the values */ |