On Tue, Jan 14, 2014 at 08:22:17PM +1100, Vadim Rozenfeld wrote: > The following patch allows to activate a partition reference > time enlightenment that is based on the host platform's support > for an Invariant Time Stamp Counter (iTSC). > > v2 -> v3 > Handle TSC sequence, scale, and offest changing during migration. > > v3 -> v4 > 1. Wrap access to iTSC page with kvm_read_guest/kvm_write_guest > suggested by Andrew Honig <[email protected]> and Marcelo > 2. iTSC data calculation/access fixes suggested by Marcelo and Paolo > > --- > arch/x86/kvm/x86.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 496bdb1..6e6debf 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1873,6 +1873,7 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 > msr, u64 data) > case HV_X64_MSR_REFERENCE_TSC: { > u64 gfn; > unsigned long addr; > + struct kvm_arch *ka = &kvm->arch; > HV_REFERENCE_TSC_PAGE tsc_ref; > memset(&tsc_ref, 0, sizeof(tsc_ref)); > if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE)) { > @@ -1883,6 +1884,13 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, > u32 msr, u64 data) > addr = gfn_to_hva(kvm, gfn); > if (kvm_is_error_hva(addr)) > return 1; > + if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) > + && ka->use_master_clock) { > + tsc_ref.tsc_sequence = 1; > + tsc_ref.tsc_scale = ((10000LL << 32) / > + vcpu->arch.virtual_tsc_khz) << 32; > + tsc_ref.tsc_offset = kvm->arch.kvmclock_offset; > + } > if (__copy_to_user((void __user *)addr, &tsc_ref, > sizeof(tsc_ref))) > return 1; > mark_page_dirty(kvm, gfn); > @@ -3871,6 +3879,27 @@ long kvm_arch_vm_ioctl(struct file *filp, > local_irq_enable(); > kvm->arch.kvmclock_offset = delta; > kvm_gen_update_masterclock(kvm); > + if (kvm->arch.hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) { > + HV_REFERENCE_TSC_PAGE tsc_ref; > + struct kvm_arch *ka = &kvm->arch; > + r = kvm_read_guest(kvm, kvm->arch.hv_tsc_page, > + &tsc_ref, sizeof(tsc_ref)); > + if (r) > + goto out; > + if (tsc_ref.tsc_sequence > + && boot_cpu_has(X86_FEATURE_CONSTANT_TSC) > + && ka->use_master_clock) { > + tsc_ref.tsc_sequence++; > + tsc_ref.tsc_scale = ((10000LL << 32) / > + __get_cpu_var(cpu_tsc_khz)) << 32; > + tsc_ref.tsc_offset = kvm->arch.kvmclock_offset; > + } else > + tsc_ref.tsc_sequence = 0; > + r = kvm_write_guest(kvm, kvm->arch.hv_tsc_page, > + &tsc_ref, sizeof(tsc_ref)); > + if (r) > + goto out; > + } > break; > }
Vadim, A short comment explaining the lifecycle of the exposed clock would be nice. Can you explain why are you setting tsc_offset to kvmclock_offset? -- 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
