On Mon, Apr 07, 2008 at 06:34:57PM -0300, Marcelo Tosatti wrote:
> On Mon, Apr 07, 2008 at 01:53:36PM +0200, Nikola Ciprich wrote:
> > Hi,
> >
> > I also tried paravirt clock again in latest git with kvm-65 patch
> > applied, and problem with cpu-lockups persists:
> >
> > [10813.654806] BUG: soft lockup - CPU#0 stuck for 61s! [swapper:0]
> > [10813.655789] CPU 0:
> > [10813.656624] Modules linked in: virtio_pci virtio_ring virtio_blk virtio
> > piix dm_snapshot dm_zero dm_mirror dm_mod ide_disk
> > ide_core sd_mod scsi_mod ext3 jbd ehci_hcd ohci_hcd uhci_hcd
> > [10813.658805] Pid: 0, comm: swapper Not tainted 2.6.25-rc7 #5
> > [10813.658805] RIP: 0010:[<ffffffff80222ab2>] [<ffffffff80222ab2>]
> > native_safe_halt+0x2/0x10
> > [10813.658805] RSP: 0018:ffffffff805adf50 EFLAGS: 00000296
> > [10813.658805] RAX: 000000019b08eeb0 RBX: ffffffff805f5000 RCX:
> > 000000019b08eeb0
> > [10813.658805] RDX: 0000000000000006 RSI: 00000000356832b0 RDI:
> > ffffffff805adf38
> > [10813.658805] RBP: 0000000000000da8 R08: 0000000000000000 R09:
> > 0000000000000000
> > [10813.658805] R10: 0000000000000001 R11: 0000000000000002 R12:
> > ffffffff802228ed
> > [10813.658805] R13: 00000000000132a0 R14: ffffffff80200bba R15:
> > ffff81000100a280
> > [10813.658805] FS: 0000000000000000(0000) GS:ffffffff80576000(0000)
> > knlGS:0000000000000000
> > [10813.658805] CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
> > [10813.658805] CR2: 00007fac0f852000 CR3: 0000000000201000 CR4:
> > 00000000000006e0
> > [10813.658805] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > 0000000000000000
> > [10813.658805] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> > 0000000000000400
> > [10813.658805]
> > [10813.658805] Call Trace:
> > [10813.658805] [<ffffffff8020a55b>] ? default_idle+0x3b/0x70
> > [10813.658805] [<ffffffff8020a520>] ? default_idle+0x0/0x70
> > [10813.658805] [<ffffffff8020a60e>] ? cpu_idle+0x7e/0xe0
> > [10813.658805] [<ffffffff80211630>] ? pda_init+0x30/0xb0
> >
> > Can I somehow help to track this one down??
>
> Hi Nikola,
>
> I just reproduced this on a UP guest. Were you seeing the exact same
> stack trace in the guest with kvm-64 ?
I think the logic to wakeup tasks in HLT is racy. Nothing prevents
a timer event from being lost if it fires in between guest exit and
vcpu_block().
Please try the patch below.
> > 2) I'm getting lot's of following messages on host, what do they mean?
> > [16836.605669] Ignoring de-assert INIT to vcpu SOMENUMBER
> > [16836.605687] SIPI to vcpu SOMENUMBER vector 0xSOMENUMBER
This is the APIC SMP initialization protocol.
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 06a241a..fdd8342 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -199,10 +199,8 @@ int __pit_timer_fn(struct kvm_kpit_state *ps)
struct kvm_kpit_timer *pt = &ps->pit_timer;
atomic_inc(&pt->pending);
- if (vcpu0 && waitqueue_active(&vcpu0->wq)) {
- vcpu0->arch.mp_state = VCPU_MP_STATE_RUNNABLE;
- wake_up_interruptible(&vcpu0->wq);
- }
+ if (vcpu0)
+ kvm_wakeup_vcpu(vcpu0, VCPU_MP_STATE_RUNNABLE);
pt->timer.expires = ktime_add_ns(pt->timer.expires, pt->period);
pt->scheduled = ktime_to_ns(pt->timer.expires);
@@ -210,6 +208,16 @@ int __pit_timer_fn(struct kvm_kpit_state *ps)
return (pt->period == 0 ? 0 : 1);
}
+int pit_has_pending_event(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;
diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
index dbfe21c..18b8a0e 100644
--- a/arch/x86/kvm/irq.c
+++ b/arch/x86/kvm/irq.c
@@ -26,6 +26,21 @@
#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_event(vcpu);
+ ret |= apic_has_pending_event(vcpu);
+
+ return ret;
+}
+EXPORT_SYMBOL(kvm_cpu_has_pending_timer);
+
+/*
* check if there is pending interrupt without
* intack.
*/
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index fa5ed5d..ff0ddb5 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -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_event(struct kvm_vcpu *vcpu);
+int apic_has_pending_event(struct kvm_vcpu *vcpu);
+
#endif
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 31280df..9973d8e 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -936,13 +936,10 @@ EXPORT_SYMBOL_GPL(kvm_lapic_enabled);
static int __apic_timer_fn(struct kvm_lapic *apic)
{
int result = 0;
- wait_queue_head_t *q = &apic->vcpu->wq;
atomic_inc(&apic->timer.pending);
- if (waitqueue_active(q)) {
- apic->vcpu->arch.mp_state = VCPU_MP_STATE_RUNNABLE;
- wake_up_interruptible(q);
- }
+ kvm_wakeup_vcpu(apic->vcpu, VCPU_MP_STATE_RUNNABLE);
+
if (apic_lvtt_period(apic)) {
result = 1;
apic->timer.dev.expires = ktime_add_ns(
@@ -952,6 +949,16 @@ static int __apic_timer_fn(struct kvm_lapic *apic)
return result;
}
+int apic_has_pending_event(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;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cb57b6a..b11ea81 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3925,10 +3944,7 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
{
int ipi_pcpu = vcpu->cpu;
- if (waitqueue_active(&vcpu->wq)) {
- wake_up_interruptible(&vcpu->wq);
- ++vcpu->stat.halt_wakeup;
- }
+ kvm_wakeup_vcpu(vcpu, vcpu->arch.mp_state);
if (vcpu->guest_mode)
smp_call_function_single(ipi_pcpu, vcpu_kick_intr, vcpu, 0, 0);
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a2ceb51..a6cb75e 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -69,6 +69,7 @@ struct kvm_vcpu {
int fpu_active;
int guest_fpu_loaded;
wait_queue_head_t wq;
+ spinlock_t wq_lock;
int sigset_active;
sigset_t sigset;
struct kvm_vcpu_stat stat;
@@ -184,6 +185,7 @@ int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn);
void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
void kvm_vcpu_block(struct kvm_vcpu *vcpu);
+void kvm_wakeup_vcpu(struct kvm_vcpu *vcpu, int mpstate);
void kvm_resched(struct kvm_vcpu *vcpu);
void kvm_load_guest_fpu(struct kvm_vcpu *vcpu);
void kvm_put_guest_fpu(struct kvm_vcpu *vcpu);
@@ -256,6 +262,7 @@ 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)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3396a5f..00d1a6c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -152,6 +152,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm,
unsigned id)
vcpu->kvm = kvm;
vcpu->vcpu_id = id;
init_waitqueue_head(&vcpu->wq);
+ spin_lock_init(&vcpu->wq_lock);
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page) {
@@ -698,6 +699,23 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
}
}
+void kvm_wakeup_vcpu(struct kvm_vcpu *vcpu, int mpstate)
+{
+ wait_queue_head_t *q = &vcpu->wq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vcpu->wq_lock, flags);
+ if (waitqueue_active(q)) {
+#ifdef CONFIG_X86
+ vcpu->arch.mp_state = mpstate;
+#endif
+ wake_up_interruptible(q);
+ ++vcpu->stat.halt_wakeup;
+ }
+ spin_unlock_irqrestore(&vcpu->wq_lock, flags);
+
+}
+
/*
* The vCPU has executed a HLT instruction with in-kernel mode enabled.
*/
@@ -705,19 +723,24 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
{
DECLARE_WAITQUEUE(wait, current);
+ spin_lock_irq(&vcpu->wq_lock);
add_wait_queue(&vcpu->wq, &wait);
/*
* 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);
+ spin_unlock_irq(&vcpu->wq_lock);
vcpu_put(vcpu);
schedule();
vcpu_load(vcpu);
+ spin_lock_irq(&vcpu->wq_lock);
}
+ spin_unlock_irq(&vcpu->wq_lock);
__set_current_state(TASK_RUNNING);
remove_wait_queue(&vcpu->wq, &wait);
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