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KVM: fix race with level interrupts

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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>
This commit is contained in:
Michael S. Tsirkin
2012-07-19 13:45:20 +03:00
committed by Marcelo Tosatti
parent d63d3e6217
commit 1a577b7247
5 changed files with 51 additions and 35 deletions
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15
arch/x86/include/asm/kvm_host.h
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@@ -816,7 +816,20 @@ int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
int kvm_pic_set_irq(void *opaque, int irq, int level);
static inline int __kvm_irq_line_state(unsigned long *irq_state,
int irq_source_id, int level)
{
/* Logical OR for level trig interrupt */
if (level)
__set_bit(irq_source_id, irq_state);
else
__clear_bit(irq_source_id, irq_state);
return !!(*irq_state);
}
int kvm_pic_set_irq(struct kvm_pic *pic, int irq, int irq_source_id, int level);
void kvm_pic_clear_all(struct kvm_pic *pic, int irq_source_id);
void kvm_inject_nmi(struct kvm_vcpu *vcpu);