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KVM: PPC: Book3S: PR: Fix signal check race
As Scott put it: > If we get a signal after the check, we want to be sure that we don't > receive the reschedule IPI until after we're in the guest, so that it > will cause another signal check. we need to have interrupts disabled from the point we do signal_check() all the way until we actually enter the guest. This patch fixes potential signal loss races. Reported-by: Scott Wood <scottwood@freescale.com> Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
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1 changed files with 20 additions and 0 deletions
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@ -51,6 +51,8 @@ static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
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#define MSR_USER32 MSR_USER
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#define MSR_USER64 MSR_USER
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#define HW_PAGE_SIZE PAGE_SIZE
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#define __hard_irq_disable local_irq_disable
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#define __hard_irq_enable local_irq_enable
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#endif
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void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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@ -776,7 +778,16 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
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/* To avoid clobbering exit_reason, only check for signals if
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* we aren't already exiting to userspace for some other
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* reason. */
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/*
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* Interrupts could be timers for the guest which we have to
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* inject again, so let's postpone them until we're in the guest
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* and if we really did time things so badly, then we just exit
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* again due to a host external interrupt.
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*/
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__hard_irq_disable();
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if (signal_pending(current)) {
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__hard_irq_enable();
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#ifdef EXIT_DEBUG
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printk(KERN_EMERG "KVM: Going back to host\n");
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#endif
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@ -959,8 +970,17 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
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kvmppc_core_prepare_to_enter(vcpu);
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/*
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* Interrupts could be timers for the guest which we have to inject
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* again, so let's postpone them until we're in the guest and if we
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* really did time things so badly, then we just exit again due to
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* a host external interrupt.
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*/
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__hard_irq_disable();
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/* No need to go into the guest when all we do is going out */
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if (signal_pending(current)) {
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__hard_irq_enable();
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kvm_run->exit_reason = KVM_EXIT_INTR;
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ret = -EINTR;
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goto out;
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