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KVM: add missing memory barrier in kvm_{make,check}_request

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kvm_make_request and kvm_check_request imply a producer-consumer
relationship; add implicit memory barriers to them.  There was indeed
already a place that was adding an explicit smp_mb() to order between
kvm_check_request and the processing of the request.  That memory
barrier can be removed (as an added benefit, kvm_check_request can use
smp_mb__after_atomic which is free on x86).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2016-03-10 16:30:22 +01:00
committed by Radim Krčmář
parent 46971a2f59
commit 2e4682ba2e
2 changed files with 11 additions and 3 deletions
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3
arch/x86/kvm/irq_comm.c
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@ -382,9 +382,6 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
u32 i, nr_ioapic_pins;
int idx;
/* kvm->irq_routing must be read after clearing
* KVM_SCAN_IOAPIC. */
smp_mb();
idx = srcu_read_lock(&kvm->irq_srcu);
table = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
nr_ioapic_pins = min_t(u32, table->nr_rt_entries,