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| author | Michael S. Tsirkin <mst@redhat.com> | 2012-07-19 13:45:20 +0300 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-07-20 16:12:00 -0300 |
| commit | 1a577b72475d161b6677c05abe57301362023bb2 (patch) | |
| tree | d8a9910f0016ada479c5a88c1a330b5e1cbc7ef1 /virt/kvm/ioapic.c | |
| parent | d63d3e6217c49b81d74141b7920bbe5950532432 (diff) | |
| download | lwn-1a577b72475d161b6677c05abe57301362023bb2.tar.gz lwn-1a577b72475d161b6677c05abe57301362023bb2.zip | |
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 <gleb@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'virt/kvm/ioapic.c')
| -rw-r--r-- | virt/kvm/ioapic.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 26fd54dc459e..ef61d529a6c4 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) { |