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Commit dd489240 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: document memory barriers for kvm->vcpus/kvm->online_vcpus 



Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c847fe88

include/linux/kvm_host.h

+4 −0
Original line number Diff line number Diff line
@@ -427,6 +427,10 @@ struct kvm { 


static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i)

{

	/* Pairs with smp_wmb() in kvm_vm_ioctl_create_vcpu, in case

	 * the caller has read kvm->online_vcpus before (as is the case

	 * for kvm_for_each_vcpu, for example).

	 */

	smp_rmb();

	return kvm->vcpus[i];

}

virt/kvm/kvm_main.c

+5 −0
Original line number Diff line number Diff line
@@ -2206,6 +2206,11 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id) 
	}



	kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;



	/*

	 * Pairs with smp_rmb() in kvm_get_vcpu.  Write kvm->vcpus

	 * before kvm->online_vcpu's incremented value.

	 */

	smp_wmb();

	atomic_inc(&kvm->online_vcpus);