tree d8a9910f0016ada479c5a88c1a330b5e1cbc7ef1
parent d63d3e6217c49b81d74141b7920bbe5950532432
author Michael S. Tsirkin <mst@redhat.com> 1342694720 +0300
committer Marcelo Tosatti <mtosatti@redhat.com> 1342811520 -0300

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>