KVM: arm64: pvtime: Fix potential loss of stolen time (2dbd780e) · Commits · 戴 / test

We should only check current->sched_info.run_delay once when updating stolen time. Otherwise there's a chance there could be a change between checks that we miss (preemption disabling comes after vcpu request checks). Signed-off-by:

Andrew Jones <drjones@redhat.com> Signed-off-by:

Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20200804170604.42662-3-drjones@redhat.com

arch/arm64/kvm/pvtime.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@
		void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
		{
		struct kvm *kvm = vcpu->kvm;
		u64 last_steal = vcpu->arch.steal.last_steal;
		u64 steal;
		__le64 steal_le;
		u64 offset;
		@@ -24,8 +25,8 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)

		/* Let's do the local bookkeeping */
		steal = vcpu->arch.steal.steal;
		steal += current->sched_info.run_delay - vcpu->arch.steal.last_steal;
		vcpu->arch.steal.last_steal = current->sched_info.run_delay;
		vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay);
		steal += vcpu->arch.steal.last_steal - last_steal;
		vcpu->arch.steal.steal = steal;

		steal_le = cpu_to_le64(steal);

Admin message