KVM: Emulate hlt in the kernel
By sleeping in the kernel when hlt is executed, we simplify the in-kernel guest interrupt path considerably. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
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@ -413,8 +413,11 @@ static void picdev_read(struct kvm_io_device *this,
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static void pic_irq_request(void *opaque, int level)
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{
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struct kvm *kvm = opaque;
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struct kvm_vcpu *vcpu = kvm->vcpus[0];
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pic_irqchip(kvm)->output = level;
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if (vcpu)
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kvm_vcpu_kick(vcpu);
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}
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struct kvm_pic *kvm_create_pic(struct kvm *kvm)
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@ -70,6 +70,10 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
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{
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int ipi_pcpu = vcpu->cpu;
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if (waitqueue_active(&vcpu->wq)) {
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wake_up_interruptible(&vcpu->wq);
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++vcpu->stat.halt_wakeup;
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}
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if (vcpu->guest_mode)
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smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0, 0);
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}
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@ -231,6 +231,7 @@ struct kvm_stat {
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u32 signal_exits;
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u32 irq_window_exits;
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u32 halt_exits;
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u32 halt_wakeup;
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u32 request_irq_exits;
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u32 irq_exits;
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u32 light_exits;
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@ -353,6 +354,7 @@ struct kvm_vcpu {
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gva_t mmio_fault_cr2;
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struct kvm_pio_request pio;
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void *pio_data;
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wait_queue_head_t wq;
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int sigset_active;
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sigset_t sigset;
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@ -76,6 +76,7 @@ static struct kvm_stats_debugfs_item {
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{ "signal_exits", STAT_OFFSET(signal_exits) },
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{ "irq_window", STAT_OFFSET(irq_window_exits) },
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{ "halt_exits", STAT_OFFSET(halt_exits) },
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{ "halt_wakeup", STAT_OFFSET(halt_wakeup) },
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{ "request_irq", STAT_OFFSET(request_irq_exits) },
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{ "irq_exits", STAT_OFFSET(irq_exits) },
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{ "light_exits", STAT_OFFSET(light_exits) },
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@ -248,6 +249,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
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vcpu->mmu.root_hpa = INVALID_PAGE;
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vcpu->kvm = kvm;
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vcpu->vcpu_id = id;
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init_waitqueue_head(&vcpu->wq);
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page = alloc_page(GFP_KERNEL | __GFP_ZERO);
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if (!page) {
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@ -1307,15 +1309,41 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
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}
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EXPORT_SYMBOL_GPL(emulate_instruction);
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/*
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* The vCPU has executed a HLT instruction with in-kernel mode enabled.
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*/
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static void kvm_vcpu_kernel_halt(struct kvm_vcpu *vcpu)
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{
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DECLARE_WAITQUEUE(wait, current);
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add_wait_queue(&vcpu->wq, &wait);
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/*
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* We will block until either an interrupt or a signal wakes us up
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*/
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while(!(irqchip_in_kernel(vcpu->kvm) && kvm_cpu_has_interrupt(vcpu))
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&& !vcpu->irq_summary
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&& !signal_pending(current)) {
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set_current_state(TASK_INTERRUPTIBLE);
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vcpu_put(vcpu);
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schedule();
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vcpu_load(vcpu);
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}
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remove_wait_queue(&vcpu->wq, &wait);
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set_current_state(TASK_RUNNING);
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}
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int kvm_emulate_halt(struct kvm_vcpu *vcpu)
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{
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if (vcpu->irq_summary ||
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(irqchip_in_kernel(vcpu->kvm) && kvm_cpu_has_interrupt(vcpu)))
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return 1;
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vcpu->run->exit_reason = KVM_EXIT_HLT;
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++vcpu->stat.halt_exits;
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if (irqchip_in_kernel(vcpu->kvm)) {
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kvm_vcpu_kernel_halt(vcpu);
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return 1;
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} else {
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vcpu->run->exit_reason = KVM_EXIT_HLT;
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return 0;
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}
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}
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EXPORT_SYMBOL_GPL(kvm_emulate_halt);
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@ -2916,6 +2944,7 @@ static long kvm_dev_ioctl(struct file *filp,
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switch (ext) {
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case KVM_CAP_IRQCHIP:
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case KVM_CAP_HLT:
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r = 1;
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break;
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default:
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@ -1398,8 +1398,11 @@ static void do_interrupt_requests(struct vcpu_svm *svm,
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static void post_kvm_run_save(struct vcpu_svm *svm,
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struct kvm_run *kvm_run)
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{
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kvm_run->ready_for_interrupt_injection
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= (svm->vcpu.interrupt_window_open &&
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if (irqchip_in_kernel(svm->vcpu.kvm))
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kvm_run->ready_for_interrupt_injection = 1;
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else
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kvm_run->ready_for_interrupt_injection =
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(svm->vcpu.interrupt_window_open &&
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svm->vcpu.irq_summary == 0);
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kvm_run->if_flag = (svm->vmcb->save.rflags & X86_EFLAGS_IF) != 0;
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kvm_run->cr8 = get_cr8(&svm->vcpu);
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@ -1961,7 +1961,11 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
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kvm_run->if_flag = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) != 0;
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kvm_run->cr8 = get_cr8(vcpu);
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kvm_run->apic_base = kvm_get_apic_base(vcpu);
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kvm_run->ready_for_interrupt_injection = (vcpu->interrupt_window_open &&
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if (irqchip_in_kernel(vcpu->kvm))
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kvm_run->ready_for_interrupt_injection = 1;
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else
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kvm_run->ready_for_interrupt_injection =
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(vcpu->interrupt_window_open &&
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vcpu->irq_summary == 0);
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}
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@ -283,6 +283,7 @@ struct kvm_signal_mask {
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* Extension capability list.
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*/
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#define KVM_CAP_IRQCHIP 0
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#define KVM_CAP_HLT 1
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/*
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* ioctls for VM fds
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