diff options
Diffstat (limited to 'arch/x86/kvm/lapic.c')
| -rw-r--r-- | arch/x86/kvm/lapic.c | 91 |
1 files changed, 70 insertions, 21 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 36c90d631096..943acbf00c69 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1301,14 +1301,42 @@ static void update_divide_count(struct kvm_lapic *apic) apic->divide_count); } +static void limit_periodic_timer_frequency(struct kvm_lapic *apic) +{ + /* + * Do not allow the guest to program periodic timers with small + * interval, since the hrtimers are not throttled by the host + * scheduler. + */ + if (apic_lvtt_period(apic) && apic->lapic_timer.period) { + s64 min_period = min_timer_period_us * 1000LL; + + if (apic->lapic_timer.period < min_period) { + pr_info_ratelimited( + "kvm: vcpu %i: requested %lld ns " + "lapic timer period limited to %lld ns\n", + apic->vcpu->vcpu_id, + apic->lapic_timer.period, min_period); + apic->lapic_timer.period = min_period; + } + } +} + static void apic_update_lvtt(struct kvm_lapic *apic) { u32 timer_mode = kvm_lapic_get_reg(apic, APIC_LVTT) & apic->lapic_timer.timer_mode_mask; if (apic->lapic_timer.timer_mode != timer_mode) { + if (apic_lvtt_tscdeadline(apic) != (timer_mode == + APIC_LVT_TIMER_TSCDEADLINE)) { + hrtimer_cancel(&apic->lapic_timer.timer); + kvm_lapic_set_reg(apic, APIC_TMICT, 0); + apic->lapic_timer.period = 0; + apic->lapic_timer.tscdeadline = 0; + } apic->lapic_timer.timer_mode = timer_mode; - hrtimer_cancel(&apic->lapic_timer.timer); + limit_periodic_timer_frequency(apic); } } @@ -1430,6 +1458,30 @@ static void start_sw_period(struct kvm_lapic *apic) HRTIMER_MODE_ABS_PINNED); } +static void update_target_expiration(struct kvm_lapic *apic, uint32_t old_divisor) +{ + ktime_t now, remaining; + u64 ns_remaining_old, ns_remaining_new; + + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) + * APIC_BUS_CYCLE_NS * apic->divide_count; + limit_periodic_timer_frequency(apic); + + now = ktime_get(); + remaining = ktime_sub(apic->lapic_timer.target_expiration, now); + if (ktime_to_ns(remaining) < 0) + remaining = 0; + + ns_remaining_old = ktime_to_ns(remaining); + ns_remaining_new = mul_u64_u32_div(ns_remaining_old, + apic->divide_count, old_divisor); + + apic->lapic_timer.tscdeadline += + nsec_to_cycles(apic->vcpu, ns_remaining_new) - + nsec_to_cycles(apic->vcpu, ns_remaining_old); + apic->lapic_timer.target_expiration = ktime_add_ns(now, ns_remaining_new); +} + static bool set_target_expiration(struct kvm_lapic *apic) { ktime_t now; @@ -1439,27 +1491,13 @@ static bool set_target_expiration(struct kvm_lapic *apic) apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) * APIC_BUS_CYCLE_NS * apic->divide_count; - if (!apic->lapic_timer.period) + if (!apic->lapic_timer.period) { + apic->lapic_timer.tscdeadline = 0; return false; - - /* - * Do not allow the guest to program periodic timers with small - * interval, since the hrtimers are not throttled by the host - * scheduler. - */ - if (apic_lvtt_period(apic)) { - s64 min_period = min_timer_period_us * 1000LL; - - if (apic->lapic_timer.period < min_period) { - pr_info_ratelimited( - "kvm: vcpu %i: requested %lld ns " - "lapic timer period limited to %lld ns\n", - apic->vcpu->vcpu_id, - apic->lapic_timer.period, min_period); - apic->lapic_timer.period = min_period; - } } + limit_periodic_timer_frequency(apic); + apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016" PRIx64 ", " "timer initial count 0x%x, period %lldns, " @@ -1515,6 +1553,9 @@ static bool start_hv_timer(struct kvm_lapic *apic) if (!apic_lvtt_period(apic) && atomic_read(&ktimer->pending)) return false; + if (!ktimer->tscdeadline) + return false; + r = kvm_x86_ops->set_hv_timer(apic->vcpu, ktimer->tscdeadline); if (r < 0) return false; @@ -1738,13 +1779,21 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) start_apic_timer(apic); break; - case APIC_TDCR: + case APIC_TDCR: { + uint32_t old_divisor = apic->divide_count; + if (val & 4) apic_debug("KVM_WRITE:TDCR %x\n", val); kvm_lapic_set_reg(apic, APIC_TDCR, val); update_divide_count(apic); + if (apic->divide_count != old_divisor && + apic->lapic_timer.period) { + hrtimer_cancel(&apic->lapic_timer.timer); + update_target_expiration(apic, old_divisor); + restart_apic_timer(apic); + } break; - + } case APIC_ESR: if (apic_x2apic_mode(apic) && val != 0) { apic_debug("KVM_WRITE:ESR not zero %x\n", val); |