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
......@@ -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;
......
......@@ -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;
......
......@@ -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;
......
......@@ -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.
......
......@@ -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
......@@ -952,6 +952,16 @@ static int __apic_timer_fn(struct kvm_lapic *apic)
return result;
}
int apic_has_pending_timer(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *lapic = vcpu->arch.apic;
if (lapic)
return atomic_read(&lapic->timer.pending);
return 0;
}
static int __inject_apic_timer_irq(struct kvm_lapic *apic)
{
int vector;
......
......@@ -269,6 +269,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm);
int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
int kvm_cpu_has_interrupt(struct kvm_vcpu *v);
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu);
void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
static inline void kvm_guest_enter(void)
......
......@@ -765,6 +765,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
* We will block until either an interrupt or a signal wakes us up
*/
while (!kvm_cpu_has_interrupt(vcpu)
&& !kvm_cpu_has_pending_timer(vcpu)
&& !signal_pending(current)
&& !kvm_arch_vcpu_runnable(vcpu)) {
set_current_state(TASK_INTERRUPTIBLE);
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment