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KVM: VMX: avoid double list add with VT-d posted interrupts
In some cases, for example involving hot-unplug of assigned devices, pi_post_block can forget to remove the vCPU from the blocked_vcpu_list. When this happens, the next call to pi_pre_block corrupts the list. Fix this in two ways. First, check vcpu->pre_pcpu in pi_pre_block and WARN instead of adding the element twice in the list. Second, always do the list removal in pi_post_block if vcpu->pre_pcpu is set (not -1). The new code keeps interrupts disabled for the whole duration of pi_pre_block/pi_post_block. This is not strictly necessary, but easier to follow. For the same reason, PI.ON is checked only after the cmpxchg, and to handle it we just call the post-block code. This removes duplication of the list removal code. Cc: Huangweidong <weidong.huang@huawei.com> Cc: Gonglei <arei.gonglei@huawei.com> Cc: wangxin <wangxinxin.wang@huawei.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Tested-by: Longpeng (Mike) <longpeng2@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -11710,10 +11710,11 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
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struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
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struct pi_desc old, new;
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unsigned int dest;
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unsigned long flags;
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do {
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old.control = new.control = pi_desc->control;
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WARN(old.nv != POSTED_INTR_WAKEUP_VECTOR,
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"Wakeup handler not enabled while the VCPU is blocked\n");
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dest = cpu_physical_id(vcpu->cpu);
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@ -11730,14 +11731,10 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
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} while (cmpxchg(&pi_desc->control, old.control,
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new.control) != old.control);
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if(vcpu->pre_pcpu != -1) {
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spin_lock_irqsave(
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&per_cpu(blocked_vcpu_on_cpu_lock,
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vcpu->pre_pcpu), flags);
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if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) {
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spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
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list_del(&vcpu->blocked_vcpu_list);
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spin_unlock_irqrestore(
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&per_cpu(blocked_vcpu_on_cpu_lock,
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vcpu->pre_pcpu), flags);
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spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
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vcpu->pre_pcpu = -1;
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}
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}
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@ -11757,7 +11754,6 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
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*/
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static int pi_pre_block(struct kvm_vcpu *vcpu)
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{
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unsigned long flags;
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unsigned int dest;
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struct pi_desc old, new;
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struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
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@ -11767,34 +11763,20 @@ static int pi_pre_block(struct kvm_vcpu *vcpu)
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!kvm_vcpu_apicv_active(vcpu))
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return 0;
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vcpu->pre_pcpu = vcpu->cpu;
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spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
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vcpu->pre_pcpu), flags);
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list_add_tail(&vcpu->blocked_vcpu_list,
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&per_cpu(blocked_vcpu_on_cpu,
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vcpu->pre_pcpu));
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spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock,
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vcpu->pre_pcpu), flags);
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WARN_ON(irqs_disabled());
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local_irq_disable();
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if (!WARN_ON_ONCE(vcpu->pre_pcpu != -1)) {
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vcpu->pre_pcpu = vcpu->cpu;
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spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
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list_add_tail(&vcpu->blocked_vcpu_list,
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&per_cpu(blocked_vcpu_on_cpu,
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vcpu->pre_pcpu));
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spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
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}
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do {
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old.control = new.control = pi_desc->control;
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/*
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* We should not block the vCPU if
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* an interrupt is posted for it.
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*/
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if (pi_test_on(pi_desc) == 1) {
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spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock,
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vcpu->pre_pcpu), flags);
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list_del(&vcpu->blocked_vcpu_list);
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spin_unlock_irqrestore(
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&per_cpu(blocked_vcpu_on_cpu_lock,
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vcpu->pre_pcpu), flags);
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vcpu->pre_pcpu = -1;
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return 1;
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}
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WARN((pi_desc->sn == 1),
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"Warning: SN field of posted-interrupts "
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"is set before blocking\n");
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@ -11819,7 +11801,12 @@ static int pi_pre_block(struct kvm_vcpu *vcpu)
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} while (cmpxchg(&pi_desc->control, old.control,
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new.control) != old.control);
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return 0;
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/* We should not block the vCPU if an interrupt is posted for it. */
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if (pi_test_on(pi_desc) == 1)
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__pi_post_block(vcpu);
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local_irq_enable();
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return (vcpu->pre_pcpu == -1);
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}
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static int vmx_pre_block(struct kvm_vcpu *vcpu)
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@ -11835,12 +11822,13 @@ static int vmx_pre_block(struct kvm_vcpu *vcpu)
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static void pi_post_block(struct kvm_vcpu *vcpu)
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{
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if (!kvm_arch_has_assigned_device(vcpu->kvm) ||
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!irq_remapping_cap(IRQ_POSTING_CAP) ||
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!kvm_vcpu_apicv_active(vcpu))
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if (vcpu->pre_pcpu == -1)
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return;
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WARN_ON(irqs_disabled());
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local_irq_disable();
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__pi_post_block(vcpu);
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local_irq_enable();
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}
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static void vmx_post_block(struct kvm_vcpu *vcpu)
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