diff options
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/x86.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4e9bd23d522d..e86f9b22eaca 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1013,10 +1013,10 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz) static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns) { - u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.last_tsc_nsec, + u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.this_tsc_nsec, vcpu->arch.virtual_tsc_mult, vcpu->arch.virtual_tsc_shift); - tsc += vcpu->arch.last_tsc_write; + tsc += vcpu->arch.this_tsc_write; return tsc; } @@ -1059,7 +1059,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data) if (nsdiff < NSEC_PER_SEC && vcpu->arch.virtual_tsc_khz == kvm->arch.last_tsc_khz) { if (!check_tsc_unstable()) { - offset = kvm->arch.last_tsc_offset; + offset = kvm->arch.cur_tsc_offset; pr_debug("kvm: matched tsc offset for %llu\n", data); } else { u64 delta = nsec_to_cycles(vcpu, elapsed); @@ -1067,20 +1067,45 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data) offset = kvm_x86_ops->compute_tsc_offset(vcpu, data); pr_debug("kvm: adjusted tsc offset by %llu\n", delta); } + } else { + /* + * We split periods of matched TSC writes into generations. + * For each generation, we track the original measured + * nanosecond time, offset, and write, so if TSCs are in + * sync, we can match exact offset, and if not, we can match + * exact software computaion in compute_guest_tsc() + * + * These values are tracked in kvm->arch.cur_xxx variables. + */ + kvm->arch.cur_tsc_generation++; + kvm->arch.cur_tsc_nsec = ns; + kvm->arch.cur_tsc_write = data; + kvm->arch.cur_tsc_offset = offset; + pr_debug("kvm: new tsc generation %u, clock %llu\n", + kvm->arch.cur_tsc_generation, data); } + + /* + * We also track th most recent recorded KHZ, write and time to + * allow the matching interval to be extended at each write. + */ kvm->arch.last_tsc_nsec = ns; kvm->arch.last_tsc_write = data; - kvm->arch.last_tsc_offset = offset; kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz; - kvm_x86_ops->write_tsc_offset(vcpu, offset); - raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); /* Reset of TSC must disable overshoot protection below */ vcpu->arch.hv_clock.tsc_timestamp = 0; - vcpu->arch.last_tsc_write = data; - vcpu->arch.last_tsc_nsec = ns; vcpu->arch.last_guest_tsc = data; + + /* Keep track of which generation this VCPU has synchronized to */ + vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation; + vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec; + vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write; + + kvm_x86_ops->write_tsc_offset(vcpu, offset); + raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); } + EXPORT_SYMBOL_GPL(kvm_write_tsc); static int kvm_guest_time_update(struct kvm_vcpu *v) |