KVM: x86: clean/fix memory barriers in irqchip_in_kernel
The memory barriers are trying to protect against concurrent RCU-based
interrupt injection, but the IRQ routing table is not valid at the time
kvm->arch.vpic is written. Fix this by writing kvm->arch.vpic last.
kvm_destroy_pic then need not set kvm->arch.vpic to NULL; modify it
to take a struct kvm_pic* and reuse it if the IOAPIC creation fails.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index ad68c73..3d782a2 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -74,7 +74,7 @@
};
struct kvm_pic *kvm_create_pic(struct kvm *kvm);
-void kvm_destroy_pic(struct kvm *kvm);
+void kvm_destroy_pic(struct kvm_pic *vpic);
int kvm_pic_read_irq(struct kvm *kvm);
void kvm_pic_update_irq(struct kvm_pic *s);
@@ -85,11 +85,11 @@
static inline int irqchip_in_kernel(struct kvm *kvm)
{
- int ret;
+ struct kvm_pic *vpic = pic_irqchip(kvm);
- ret = (pic_irqchip(kvm) != NULL);
+ /* Read vpic before kvm->irq_routing. */
smp_rmb();
- return ret;
+ return vpic != NULL;
}
void kvm_pic_reset(struct kvm_kpic_state *s);