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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2008-06-06 16:37:36 -0300 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2008-06-24 12:16:59 +0300 |
| commit | 06e05645661211b9eaadaf6344c335d2e80f0ba2 (patch) | |
| tree | 8846d2a5052aec44141e811c0a76fdb39c2e77ca | |
| parent | d4acf7e7abe45457e751525a2a4d5b693dfdd597 (diff) | |
| download | linux-06e05645661211b9eaadaf6344c335d2e80f0ba2.tar.gz linux-06e05645661211b9eaadaf6344c335d2e80f0ba2.tar.bz2 linux-06e05645661211b9eaadaf6344c335d2e80f0ba2.zip | |
KVM: close timer injection race window in __vcpu_run
If a timer fires after kvm_inject_pending_timer_irqs() but before
local_irq_disable() the code will enter guest mode and only inject such
timer interrupt the next time an unrelated event causes an exit.
It would be simpler if the timer->pending irq conversion could be done
with IRQ's disabled, so that the above problem cannot happen.
For now introduce a new vcpu requests bit to cancel guest entry.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
| -rw-r--r-- | arch/x86/kvm/i8254.c | 9 | ||||
| -rw-r--r-- | arch/x86/kvm/lapic.c | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 1 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 1 |
4 files changed, 9 insertions, 3 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index f2f5d260874e..3829aa7b663f 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -200,9 +200,12 @@ int __pit_timer_fn(struct kvm_kpit_state *ps) atomic_inc(&pt->pending); smp_mb__after_atomic_inc(); - if (vcpu0 && waitqueue_active(&vcpu0->wq)) { - vcpu0->arch.mp_state = KVM_MP_STATE_RUNNABLE; - wake_up_interruptible(&vcpu0->wq); + if (vcpu0) { + set_bit(KVM_REQ_PENDING_TIMER, &vcpu0->requests); + if (waitqueue_active(&vcpu0->wq)) { + vcpu0->arch.mp_state = KVM_MP_STATE_RUNNABLE; + wake_up_interruptible(&vcpu0->wq); + } } pt->timer.expires = ktime_add_ns(pt->timer.expires, pt->period); diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index c297c50eba63..ebc03f5ae162 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -940,6 +940,7 @@ static int __apic_timer_fn(struct kvm_lapic *apic) wait_queue_head_t *q = &apic->vcpu->wq; atomic_inc(&apic->timer.pending); + set_bit(KVM_REQ_PENDING_TIMER, &apic->vcpu->requests); if (waitqueue_active(q)) { apic->vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; wake_up_interruptible(q); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b90744a1dc3a..b08812d6b34c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2774,6 +2774,7 @@ again: } } + clear_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests); kvm_inject_pending_timer_irqs(vcpu); preempt_disable(); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 092b1b25291d..de9d1df4bba2 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -33,6 +33,7 @@ #define KVM_REQ_REPORT_TPR_ACCESS 2 #define KVM_REQ_MMU_RELOAD 3 #define KVM_REQ_TRIPLE_FAULT 4 +#define KVM_REQ_PENDING_TIMER 5 struct kvm_vcpu; extern struct kmem_cache *kvm_vcpu_cache; |