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Commit 3d80840d authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Avi Kivity
Browse files

KVM: hlt emulation should take in-kernel APIC/PIT timers into account 



Timers that fire between guest hlt and vcpu_block's add_wait_queue() are
ignored, possibly resulting in hangs.

Also make sure that atomic_inc and waitqueue_active tests happen in the
specified order, otherwise the following race is open:

CPU0                                        CPU1
                                            if (waitqueue_active(wq))
add_wait_queue()
if (!atomic_read(pit_timer->pending))
    schedule()
                                            atomic_inc(pit_timer->pending)

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 3564990a

arch/ia64/kvm/kvm-ia64.c

+5 −0
Original line number Diff line number Diff line
@@ -1778,6 +1778,11 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu) 
	return 0;

}



int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)

{

	return 0;

}



gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)

{

	return gfn;

arch/s390/kvm/interrupt.c

+5 −0
Original line number Diff line number Diff line
@@ -325,6 +325,11 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu) 
	return rc;

}



int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)

{

	return 0;

}



int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)

{

	u64 now, sltime;

arch/x86/kvm/i8254.c

+10 −0
Original line number Diff line number Diff line
@@ -212,6 +212,16 @@ int __pit_timer_fn(struct kvm_kpit_state *ps) 
	return (pt->period == 0 ? 0 : 1);

}



int pit_has_pending_timer(struct kvm_vcpu *vcpu)

{

	struct kvm_pit *pit = vcpu->kvm->arch.vpit;



	if (pit && vcpu->vcpu_id == 0)

		return atomic_read(&pit->pit_state.pit_timer.pending);



	return 0;

}



static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)

{

	struct kvm_kpit_state *ps;

arch/x86/kvm/irq.c

+15 −0
Original line number Diff line number Diff line
@@ -25,6 +25,21 @@ 
#include "irq.h"

#include "i8254.h"



/*

 * check if there are pending timer events

 * to be processed.

 */

int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)

{

	int ret;



	ret = pit_has_pending_timer(vcpu);

	ret |= apic_has_pending_timer(vcpu);



	return ret;

}

EXPORT_SYMBOL(kvm_cpu_has_pending_timer);



/*

 * check if there is pending interrupt without

 * intack.

arch/x86/kvm/irq.h

+3 −0
Original line number Diff line number Diff line
@@ -85,4 +85,7 @@ void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu); 
void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu);

void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu);



int pit_has_pending_timer(struct kvm_vcpu *vcpu);

int apic_has_pending_timer(struct kvm_vcpu *vcpu);



#endif