diff options
| -rw-r--r-- | virt/kvm/ioapic.c | 74 |
1 files changed, 50 insertions, 24 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 25e16a6898ed..270f7fe73f39 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -163,6 +163,55 @@ static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic) return false; } +static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq, + int irq_level, bool line_status) +{ + union kvm_ioapic_redirect_entry entry; + u32 mask = 1 << irq; + u32 old_irr; + int edge, ret; + + entry = ioapic->redirtbl[irq]; + edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG); + + if (!irq_level) { + ioapic->irr &= ~mask; + ret = 1; + goto out; + } + + /* + * Return 0 for coalesced interrupts; for edge-triggered interrupts, + * this only happens if a previous edge has not been delivered due + * do masking. For level interrupts, the remote_irr field tells + * us if the interrupt is waiting for an EOI. + * + * RTC is special: it is edge-triggered, but userspace likes to know + * if it has been already ack-ed via EOI because coalesced RTC + * interrupts lead to time drift in Windows guests. So we track + * EOI manually for the RTC interrupt. + */ + if (irq == RTC_GSI && line_status && + rtc_irq_check_coalesced(ioapic)) { + ret = 0; + goto out; + } + + old_irr = ioapic->irr; + ioapic->irr |= mask; + if ((edge && old_irr == ioapic->irr) || + (!edge && entry.fields.remote_irr)) { + ret = 0; + goto out; + } + + ret = ioapic_service(ioapic, irq, line_status); + +out: + trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0); + return ret; +} + static void update_handled_vectors(struct kvm_ioapic *ioapic) { DECLARE_BITMAP(handled_vectors, 256); @@ -308,38 +357,15 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status) int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id, int level, bool line_status) { - u32 old_irr; - u32 mask = 1 << irq; - union kvm_ioapic_redirect_entry entry; int ret, irq_level; BUG_ON(irq < 0 || irq >= IOAPIC_NUM_PINS); spin_lock(&ioapic->lock); - old_irr = ioapic->irr; irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq], irq_source_id, level); - entry = ioapic->redirtbl[irq]; - if (!irq_level) { - ioapic->irr &= ~mask; - ret = 1; - } else { - int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG); + ret = ioapic_set_irq(ioapic, irq, irq_level, line_status); - if (irq == RTC_GSI && line_status && - rtc_irq_check_coalesced(ioapic)) { - ret = 0; /* coalesced */ - goto out; - } - ioapic->irr |= mask; - if ((edge && old_irr != ioapic->irr) || - (!edge && !entry.fields.remote_irr)) - ret = ioapic_service(ioapic, irq, line_status); - else - ret = 0; /* report coalesced interrupt */ - } -out: - trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0); spin_unlock(&ioapic->lock); return ret; |