diff options
Diffstat (limited to 'arch/x86/kvm/lapic.c')
| -rw-r--r-- | arch/x86/kvm/lapic.c | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index fbb0e6df121b..91ffb63397f5 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -70,6 +70,11 @@ #define APIC_BROADCAST 0xFF #define X2APIC_BROADCAST 0xFFFFFFFFul +static bool lapic_timer_advance_adjust_done = false; +#define LAPIC_TIMER_ADVANCE_ADJUST_DONE 100 +/* step-by-step approximation to mitigate fluctuation */ +#define LAPIC_TIMER_ADVANCE_ADJUST_STEP 8 + static inline int apic_test_vector(int vec, void *bitmap) { return test_bit(VEC_POS(vec), (bitmap) + REG_POS(vec)); @@ -1472,7 +1477,7 @@ static bool lapic_timer_int_injected(struct kvm_vcpu *vcpu) void wait_lapic_expire(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; - u64 guest_tsc, tsc_deadline; + u64 guest_tsc, tsc_deadline, ns; if (!lapic_in_kernel(vcpu)) return; @@ -1492,6 +1497,24 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu) if (guest_tsc < tsc_deadline) __delay(min(tsc_deadline - guest_tsc, nsec_to_cycles(vcpu, lapic_timer_advance_ns))); + + if (!lapic_timer_advance_adjust_done) { + /* too early */ + if (guest_tsc < tsc_deadline) { + ns = (tsc_deadline - guest_tsc) * 1000000ULL; + do_div(ns, vcpu->arch.virtual_tsc_khz); + lapic_timer_advance_ns -= min((unsigned int)ns, + lapic_timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP); + } else { + /* too late */ + ns = (guest_tsc - tsc_deadline) * 1000000ULL; + do_div(ns, vcpu->arch.virtual_tsc_khz); + lapic_timer_advance_ns += min((unsigned int)ns, + lapic_timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP); + } + if (abs(guest_tsc - tsc_deadline) < LAPIC_TIMER_ADVANCE_ADJUST_DONE) + lapic_timer_advance_adjust_done = true; + } } static void start_sw_tscdeadline(struct kvm_lapic *apic) |