Commit c300ab9f authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: Replace late check_nested_events() hack with more precise fix 



Add an argument to interrupt_allowed and nmi_allowed, to checking if
interrupt injection is blocked.  Use the hook to handle the case where
an interrupt arrives between check_nested_events() and the injection
logic.  Drop the retry of check_nested_events() that hack-a-fixed the
same condition.

Blocking injection is also a bit of a hack, e.g. KVM should do exiting
and non-exiting interrupt processing in a single pass, but it's a more
precise hack.  The old comment is also misleading, e.g. KVM_REQ_EVENT is
purely an optimization, setting it on every run loop (which KVM doesn't
do) should not affect functionality, only performance.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200423022550.15113-13-sean.j.christopherson@intel.com>
[Extend to SVM, add SMI and NMI.  Even though NMI and SMI cannot come
 asynchronously right now, making the fix generic is easy and removes a
 special case. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 7ab0abdb

arch/x86/include/asm/kvm_host.h

+3 −3
Original line number Diff line number Diff line
@@ -1138,8 +1138,8 @@ struct kvm_x86_ops { 
	void (*set_nmi)(struct kvm_vcpu *vcpu);

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

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

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

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

	bool (*interrupt_allowed)(struct kvm_vcpu *vcpu, bool for_injection);

	bool (*nmi_allowed)(struct kvm_vcpu *vcpu, bool for_injection);

	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);
@@ -1237,7 +1237,7 @@ struct kvm_x86_ops { 


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



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

	bool (*smi_allowed)(struct kvm_vcpu *vcpu, bool for_injection);

	int (*pre_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);

	int (*pre_leave_smm)(struct kvm_vcpu *vcpu, const char *smstate);

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

arch/x86/kvm/svm/svm.c

+20 −5
Original line number Diff line number Diff line
@@ -3083,12 +3083,16 @@ bool svm_nmi_blocked(struct kvm_vcpu *vcpu) 
	return ret;

}



static bool svm_nmi_allowed(struct kvm_vcpu *vcpu)

static bool svm_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	if (svm->nested.nested_run_pending)

		return false;



	/* An NMI must not be injected into L2 if it's supposed to VM-Exit.  */

	if (for_injection && is_guest_mode(vcpu) && nested_exit_on_nmi(svm))

		return false;



	return !svm_nmi_blocked(vcpu);

}
@@ -3138,12 +3142,19 @@ bool svm_interrupt_blocked(struct kvm_vcpu *vcpu) 
	return (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK);

}



static bool svm_interrupt_allowed(struct kvm_vcpu *vcpu)

static bool svm_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	if (svm->nested.nested_run_pending)

		return false;



	/*

	 * An IRQ must not be injected into L2 if it's supposed to VM-Exit,

	 * e.g. if the IRQ arrived asynchronously after checking nested events.

	 */

	if (for_injection && is_guest_mode(vcpu) && nested_exit_on_intr(svm))

		return false;



	return !svm_interrupt_blocked(vcpu);

}
@@ -3812,12 +3823,16 @@ bool svm_smi_blocked(struct kvm_vcpu *vcpu) 
	return is_smm(vcpu);

}



static bool svm_smi_allowed(struct kvm_vcpu *vcpu)

static bool svm_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	if (svm->nested.nested_run_pending)

		return false;



	/* An SMI must not be injected into L2 if it's supposed to VM-Exit.  */

	if (for_injection && is_guest_mode(vcpu) && nested_exit_on_smi(svm))

		return false;



	return !svm_smi_blocked(vcpu);

}

arch/x86/kvm/vmx/vmx.c

+14 −3
Original line number Diff line number Diff line
@@ -4523,11 +4523,15 @@ bool vmx_nmi_blocked(struct kvm_vcpu *vcpu) 
		 GUEST_INTR_STATE_NMI));

}



static bool vmx_nmi_allowed(struct kvm_vcpu *vcpu)

static bool vmx_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)

{

	if (to_vmx(vcpu)->nested.nested_run_pending)

		return false;



	/* An NMI must not be injected into L2 if it's supposed to VM-Exit.  */

	if (for_injection && is_guest_mode(vcpu) && nested_exit_on_nmi(vcpu))

		return false;



	return !vmx_nmi_blocked(vcpu);

}
@@ -4541,11 +4545,18 @@ bool vmx_interrupt_blocked(struct kvm_vcpu *vcpu) 
		(GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS));

}



static bool vmx_interrupt_allowed(struct kvm_vcpu *vcpu)

static bool vmx_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection)

{

	if (to_vmx(vcpu)->nested.nested_run_pending)

		return false;



       /*

        * An IRQ must not be injected into L2 if it's supposed to VM-Exit,

        * e.g. if the IRQ arrived asynchronously after checking nested events.

        */

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

		return false;



	return !vmx_interrupt_blocked(vcpu);

}
@@ -7688,7 +7699,7 @@ static void vmx_setup_mce(struct kvm_vcpu *vcpu) 
			~FEAT_CTL_LMCE_ENABLED;

}



static bool vmx_smi_allowed(struct kvm_vcpu *vcpu)

static bool vmx_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)

{

	/* we need a nested vmexit to enter SMM, postpone if run is pending */

	if (to_vmx(vcpu)->nested.nested_run_pending)

arch/x86/kvm/x86.c

+12 −24
Original line number Diff line number Diff line
@@ -7766,33 +7766,21 @@ static int inject_pending_event(struct kvm_vcpu *vcpu) 
	if (kvm_event_needs_reinjection(vcpu))

		return 0;



	if (vcpu->arch.smi_pending && kvm_x86_ops.smi_allowed(vcpu)) {

	if (vcpu->arch.smi_pending &&

	    kvm_x86_ops.smi_allowed(vcpu, true)) {

		vcpu->arch.smi_pending = false;

		++vcpu->arch.smi_count;

		enter_smm(vcpu);

	} else if (vcpu->arch.nmi_pending && kvm_x86_ops.nmi_allowed(vcpu)) {

	} else if (vcpu->arch.nmi_pending &&

		   kvm_x86_ops.nmi_allowed(vcpu, true)) {

		--vcpu->arch.nmi_pending;

		vcpu->arch.nmi_injected = true;

		kvm_x86_ops.set_nmi(vcpu);

	} else if (kvm_cpu_has_injectable_intr(vcpu)) {

		/*

		 * Because interrupts can be injected asynchronously, we are

		 * calling check_nested_events again here to avoid a race condition.

		 * See https://lkml.org/lkml/2014/7/2/60 for discussion about this

		 * proposal and current concerns.  Perhaps we should be setting

		 * KVM_REQ_EVENT only on certain events and not unconditionally?

		 */

		if (is_guest_mode(vcpu)) {

			r = kvm_x86_ops.nested_ops->check_events(vcpu);

			if (r != 0)

				return r;

		}

		if (kvm_x86_ops.interrupt_allowed(vcpu)) {

			kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu),

					    false);

	} else if (kvm_cpu_has_injectable_intr(vcpu) &&

		   kvm_x86_ops.interrupt_allowed(vcpu, true)) {

		kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu), false);

		kvm_x86_ops.set_irq(vcpu);

	}

	}



	return 0;

}
@@ -10203,12 +10191,12 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu) 


	if (kvm_test_request(KVM_REQ_NMI, vcpu) ||

	    (vcpu->arch.nmi_pending &&

	     kvm_x86_ops.nmi_allowed(vcpu)))

	     kvm_x86_ops.nmi_allowed(vcpu, false)))

		return true;



	if (kvm_test_request(KVM_REQ_SMI, vcpu) ||

	    (vcpu->arch.smi_pending &&

	     kvm_x86_ops.smi_allowed(vcpu)))

	     kvm_x86_ops.smi_allowed(vcpu, false)))

		return true;



	if (kvm_arch_interrupt_allowed(vcpu) &&
@@ -10260,7 +10248,7 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) 


int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu)

{

	return kvm_x86_ops.interrupt_allowed(vcpu);

	return kvm_x86_ops.interrupt_allowed(vcpu, false);

}



unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu)
@@ -10425,7 +10413,7 @@ bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu) 
	 * If interrupts are off we cannot even use an artificial

	 * halt state.

	 */

	return kvm_x86_ops.interrupt_allowed(vcpu);

	return kvm_arch_interrupt_allowed(vcpu);

}



void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,

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