From 1a577b72475d161b6677c05abe57301362023bb2 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 19 Jul 2012 13:45:20 +0300 Subject: KVM: fix race with level interrupts When more than 1 source id is in use for the same GSI, we have the following race related to handling irq_states race: CPU 0 clears bit 0. CPU 0 read irq_state as 0. CPU 1 sets level to 1. CPU 1 calls kvm_ioapic_set_irq(1). CPU 0 calls kvm_ioapic_set_irq(0). Now ioapic thinks the level is 0 but irq_state is not 0. Fix by performing all irq_states bitmap handling under pic/ioapic lock. This also removes the need for atomics with irq_states handling. Reported-by: Gleb Natapov Signed-off-by: Michael S. Tsirkin Signed-off-by: Marcelo Tosatti --- virt/kvm/ioapic.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'virt/kvm/ioapic.c') diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 26fd54dc459..ef61d529a6c 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -191,7 +191,8 @@ static int ioapic_deliver(struct kvm_ioapic *ioapic, int irq) return kvm_irq_delivery_to_apic(ioapic->kvm, NULL, &irqe); } -int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) +int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id, + int level) { u32 old_irr; u32 mask = 1 << irq; @@ -201,9 +202,11 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) spin_lock(&ioapic->lock); old_irr = ioapic->irr; if (irq >= 0 && irq < IOAPIC_NUM_PINS) { + int irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq], + irq_source_id, level); entry = ioapic->redirtbl[irq]; - level ^= entry.fields.polarity; - if (!level) + irq_level ^= entry.fields.polarity; + if (!irq_level) ioapic->irr &= ~mask; else { int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG); @@ -221,6 +224,16 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) return ret; } +void kvm_ioapic_clear_all(struct kvm_ioapic *ioapic, int irq_source_id) +{ + int i; + + spin_lock(&ioapic->lock); + for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++) + __clear_bit(irq_source_id, &ioapic->irq_states[i]); + spin_unlock(&ioapic->lock); +} + static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int vector, int trigger_mode) { -- cgit v1.2.3