Commit b463a6f7 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: Non-atomic interrupt injection 



Change the interrupt injection code to work from preemptible, interrupts
enabled context.  This works by adding a ->cancel_injection() operation
that undoes an injection in case we were not able to actually enter the guest
(this condition could never happen with atomic injection).

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 83422e17

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -552,6 +552,7 @@ struct kvm_x86_ops { 
	void (*queue_exception)(struct kvm_vcpu *vcpu, unsigned nr,

				bool has_error_code, u32 error_code,

				bool reinject);

	void (*cancel_injection)(struct kvm_vcpu *vcpu);

	int (*interrupt_allowed)(struct kvm_vcpu *vcpu);

	int (*nmi_allowed)(struct kvm_vcpu *vcpu);

	bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);

arch/x86/kvm/svm.c

+12 −0
Original line number Diff line number Diff line
@@ -3261,6 +3261,17 @@ static void svm_complete_interrupts(struct vcpu_svm *svm) 
	}

}



static void svm_cancel_injection(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	struct vmcb_control_area *control = &svm->vmcb->control;



	control->exit_int_info = control->event_inj;

	control->exit_int_info_err = control->event_inj_err;

	control->event_inj = 0;

	svm_complete_interrupts(svm);

}



#ifdef CONFIG_X86_64

#define R "r"

#else
@@ -3631,6 +3642,7 @@ static struct kvm_x86_ops svm_x86_ops = { 
	.set_irq = svm_set_irq,

	.set_nmi = svm_inject_nmi,

	.queue_exception = svm_queue_exception,

	.cancel_injection = svm_cancel_injection,

	.interrupt_allowed = svm_interrupt_allowed,

	.nmi_allowed = svm_nmi_allowed,

	.get_nmi_mask = svm_get_nmi_mask,

arch/x86/kvm/vmx.c

+11 −0
Original line number Diff line number Diff line
@@ -3895,6 +3895,16 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx) 
				  IDT_VECTORING_ERROR_CODE);

}



static void vmx_cancel_injection(struct kvm_vcpu *vcpu)

{

	__vmx_complete_interrupts(to_vmx(vcpu),

				  vmcs_read32(VM_ENTRY_INTR_INFO_FIELD),

				  VM_ENTRY_INSTRUCTION_LEN,

				  VM_ENTRY_EXCEPTION_ERROR_CODE);



	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);

}



/*

 * Failure to inject an interrupt should give us the information

 * in IDT_VECTORING_INFO_FIELD.  However, if the failure occurs
@@ -4348,6 +4358,7 @@ static struct kvm_x86_ops vmx_x86_ops = { 
	.set_irq = vmx_inject_irq,

	.set_nmi = vmx_inject_nmi,

	.queue_exception = vmx_queue_exception,

	.cancel_injection = vmx_cancel_injection,

	.interrupt_allowed = vmx_interrupt_allowed,

	.nmi_allowed = vmx_nmi_allowed,

	.get_nmi_mask = vmx_get_nmi_mask,

arch/x86/kvm/x86.c

+16 −20
Original line number Diff line number Diff line
@@ -5005,7 +5005,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
	int r;

	bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&

		vcpu->run->request_interrupt_window;

	bool req_event;



	if (vcpu->requests) {

		if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu))
@@ -5041,6 +5040,21 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
	if (unlikely(r))

		goto out;



	if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {

		inject_pending_event(vcpu);



		/* enable NMI/IRQ window open exits if needed */

		if (vcpu->arch.nmi_pending)

			kvm_x86_ops->enable_nmi_window(vcpu);

		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)

			kvm_x86_ops->enable_irq_window(vcpu);



		if (kvm_lapic_enabled(vcpu)) {

			update_cr8_intercept(vcpu);

			kvm_lapic_sync_to_vapic(vcpu);

		}

	}



	preempt_disable();



	kvm_x86_ops->prepare_guest_switch(vcpu);
@@ -5053,35 +5067,17 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 


	local_irq_disable();



	req_event = kvm_check_request(KVM_REQ_EVENT, vcpu);



	if (!atomic_read(&vcpu->guest_mode) || vcpu->requests

	    || need_resched() || signal_pending(current)) {

		if (req_event)

			kvm_make_request(KVM_REQ_EVENT, vcpu);

		atomic_set(&vcpu->guest_mode, 0);

		smp_wmb();

		local_irq_enable();

		preempt_enable();

		kvm_x86_ops->cancel_injection(vcpu);

		r = 1;

		goto out;

	}



	if (req_event || req_int_win) {

		inject_pending_event(vcpu);



		/* enable NMI/IRQ window open exits if needed */

		if (vcpu->arch.nmi_pending)

			kvm_x86_ops->enable_nmi_window(vcpu);

		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)

			kvm_x86_ops->enable_irq_window(vcpu);



		if (kvm_lapic_enabled(vcpu)) {

			update_cr8_intercept(vcpu);

			kvm_lapic_sync_to_vapic(vcpu);

		}

	}



	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);



	kvm_guest_enter();

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