Commit 730dca42 authored by Jan Kiszka's avatar Jan Kiszka Committed by Gleb Natapov
Browse files

KVM: x86: Rework request for immediate exit 



The VMX implementation of enable_irq_window raised
KVM_REQ_IMMEDIATE_EXIT after we checked it in vcpu_enter_guest. This
caused infinite loops on vmentry. Fix it by letting enable_irq_window
signal the need for an immediate exit via its return value and drop
KVM_REQ_IMMEDIATE_EXIT.

This issue only affects nested VMX scenarios.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 6614c7d0

arch/x86/include/asm/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -694,7 +694,7 @@ struct kvm_x86_ops { 
	bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);

	void (*set_nmi_mask)(struct kvm_vcpu *vcpu, bool masked);

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

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

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

	void (*update_cr8_intercept)(struct kvm_vcpu *vcpu, int tpr, int irr);

	int (*vm_has_apicv)(struct kvm *kvm);

	void (*hwapic_irr_update)(struct kvm_vcpu *vcpu, int max_irr);

arch/x86/kvm/svm.c

+2 −1
Original line number Diff line number Diff line
@@ -3632,7 +3632,7 @@ static int svm_interrupt_allowed(struct kvm_vcpu *vcpu) 
	return ret;

}



static void enable_irq_window(struct kvm_vcpu *vcpu)

static int enable_irq_window(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);
@@ -3646,6 +3646,7 @@ static void enable_irq_window(struct kvm_vcpu *vcpu) 
		svm_set_vintr(svm);

		svm_inject_irq(svm, 0x0);

	}

	return 0;

}



static void enable_nmi_window(struct kvm_vcpu *vcpu)

arch/x86/kvm/vmx.c

+8 −7
Original line number Diff line number Diff line
@@ -4398,22 +4398,23 @@ static bool nested_exit_on_nmi(struct kvm_vcpu *vcpu) 
		PIN_BASED_NMI_EXITING;

}



static void enable_irq_window(struct kvm_vcpu *vcpu)

static int enable_irq_window(struct kvm_vcpu *vcpu)

{

	u32 cpu_based_vm_exec_control;

	if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu)) {



	if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))

		/*

		 * We get here if vmx_interrupt_allowed() said we can't

		 * inject to L1 now because L2 must run. Ask L2 to exit

		 * right after entry, so we can inject to L1 more promptly.

		 * inject to L1 now because L2 must run. The caller will have

		 * to make L2 exit right after entry, so we can inject to L1

		 * more promptly.

		 */

		kvm_make_request(KVM_REQ_IMMEDIATE_EXIT, vcpu);

		return;

	}

		return -EBUSY;



	cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);

	cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;

	vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);

	return 0;

}



static void enable_nmi_window(struct kvm_vcpu *vcpu)

arch/x86/kvm/x86.c

+3 −4
Original line number Diff line number Diff line
@@ -5692,7 +5692,7 @@ 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_immediate_exit = 0;

	bool req_immediate_exit = false;



	if (vcpu->requests) {

		if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu))
@@ -5734,8 +5734,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
			record_steal_time(vcpu);

		if (kvm_check_request(KVM_REQ_NMI, vcpu))

			process_nmi(vcpu);

		req_immediate_exit =

			kvm_check_request(KVM_REQ_IMMEDIATE_EXIT, vcpu);

		if (kvm_check_request(KVM_REQ_PMU, vcpu))

			kvm_handle_pmu_event(vcpu);

		if (kvm_check_request(KVM_REQ_PMI, vcpu))
@@ -5757,7 +5755,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
		if (vcpu->arch.nmi_pending)

			kvm_x86_ops->enable_nmi_window(vcpu);

		else if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)

			kvm_x86_ops->enable_irq_window(vcpu);

			req_immediate_exit =

				kvm_x86_ops->enable_irq_window(vcpu) != 0;



		if (kvm_lapic_enabled(vcpu)) {

			/*

include/linux/kvm_host.h

+7 −8
Original line number Diff line number Diff line
@@ -119,14 +119,13 @@ static inline bool is_error_page(struct page *page) 
#define KVM_REQ_APF_HALT          12

#define KVM_REQ_STEAL_UPDATE      13

#define KVM_REQ_NMI               14

#define KVM_REQ_IMMEDIATE_EXIT    15

#define KVM_REQ_PMU               16

#define KVM_REQ_PMI               17

#define KVM_REQ_WATCHDOG          18

#define KVM_REQ_MASTERCLOCK_UPDATE 19

#define KVM_REQ_MCLOCK_INPROGRESS 20

#define KVM_REQ_EPR_EXIT          21

#define KVM_REQ_SCAN_IOAPIC       22

#define KVM_REQ_PMU               15

#define KVM_REQ_PMI               16

#define KVM_REQ_WATCHDOG          17

#define KVM_REQ_MASTERCLOCK_UPDATE 18

#define KVM_REQ_MCLOCK_INPROGRESS 19

#define KVM_REQ_EPR_EXIT          20

#define KVM_REQ_SCAN_IOAPIC       21



#define KVM_USERSPACE_IRQ_SOURCE_ID		0

#define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID	1

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