# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1217499210 -3600
# Node ID 482c16b55c28cd8dfc7b6dc93d0987f0b7bed42d
# Parent 82edb8c9ae178e32aaffc21c821767633e030b6f
evtchn: Avoid spurious event-channel notifications across unbind/bind.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
Signed-off-by: Huacai Chen <huacai.chen@xxxxxxxxx>
---
xen/arch/ia64/xen/irq.c | 3 --
xen/arch/x86/irq.c | 3 --
xen/common/domain.c | 2 +
xen/common/event_channel.c | 57 ++++++++++++++++++++++++++-------------------
xen/include/xen/irq.h | 2 -
xen/include/xen/sched.h | 2 +
xen/include/xen/spinlock.h | 4 +--
7 files changed, 43 insertions(+), 30 deletions(-)
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/arch/ia64/xen/irq.c
--- a/xen/arch/ia64/xen/irq.c Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/arch/ia64/xen/irq.c Thu Jul 31 11:13:30 2008 +0100
@@ -459,7 +459,7 @@ int pirq_guest_bind(struct vcpu *v, int
return rc;
}
-int pirq_guest_unbind(struct domain *d, int irq)
+void pirq_guest_unbind(struct domain *d, int irq)
{
irq_desc_t *desc = &irq_desc[irq];
irq_guest_action_t *action;
@@ -493,7 +493,6 @@ int pirq_guest_unbind(struct domain *d,
}
spin_unlock_irqrestore(&desc->lock, flags);
- return 0;
}
void
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/arch/x86/irq.c Thu Jul 31 11:13:30 2008 +0100
@@ -573,7 +573,7 @@ int pirq_guest_bind(struct vcpu *v, int
return rc;
}
-int pirq_guest_unbind(struct domain *d, int irq)
+void pirq_guest_unbind(struct domain *d, int irq)
{
unsigned int vector;
irq_desc_t *desc;
@@ -660,7 +660,6 @@ int pirq_guest_unbind(struct domain *d,
out:
spin_unlock_irqrestore(&desc->lock, flags);
- return 0;
}
extern void dump_ioapic_irq_info(void);
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/common/domain.c
--- a/xen/common/domain.c Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/common/domain.c Thu Jul 31 11:13:30 2008 +0100
@@ -137,6 +137,8 @@ struct vcpu *alloc_vcpu(
v->runstate.state = is_idle_vcpu(v) ? RUNSTATE_running : RUNSTATE_offline;
v->runstate.state_entry_time = NOW();
+ spin_lock_init(&v->virq_lock);
+
if ( !is_idle_domain(d) )
{
set_bit(_VPF_down, &v->pause_flags);
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/common/event_channel.c
--- a/xen/common/event_channel.c Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/common/event_channel.c Thu Jul 31 11:13:30 2008 +0100
@@ -386,14 +386,18 @@ static long __evtchn_close(struct domain
break;
case ECS_PIRQ:
- if ( (rc = pirq_guest_unbind(d1, chn1->u.pirq)) == 0 )
- d1->pirq_to_evtchn[chn1->u.pirq] = 0;
+ pirq_guest_unbind(d1, chn1->u.pirq);
+ d1->pirq_to_evtchn[chn1->u.pirq] = 0;
break;
case ECS_VIRQ:
for_each_vcpu ( d1, v )
- if ( v->virq_to_evtchn[chn1->u.virq] == port1 )
- v->virq_to_evtchn[chn1->u.virq] = 0;
+ {
+ if ( v->virq_to_evtchn[chn1->u.virq] != port1 )
+ continue;
+ v->virq_to_evtchn[chn1->u.virq] = 0;
+ spin_barrier(&v->virq_lock);
+ }
break;
case ECS_IPI:
@@ -447,6 +451,9 @@ static long __evtchn_close(struct domain
BUG();
}
+ /* Clear pending event to avoid unexpected behavior on re-bind. */
+ clear_bit(port1, &shared_info(d1, evtchn_pending));
+
/* Reset binding to vcpu0 when the channel is freed. */
chn1->state = ECS_FREE;
chn1->notify_vcpu_id = 0;
@@ -573,37 +580,33 @@ static int evtchn_set_pending(struct vcp
return 0;
}
+int guest_enabled_event(struct vcpu *v, int virq)
+{
+ return ((v != NULL) && (v->virq_to_evtchn[virq] != 0));
+}
void send_guest_vcpu_virq(struct vcpu *v, int virq)
{
+ unsigned long flags;
int port;
ASSERT(!virq_is_global(virq));
+
+ spin_lock_irqsave(&v->virq_lock, flags);
port = v->virq_to_evtchn[virq];
if ( unlikely(port == 0) )
- return;
+ goto out;
evtchn_set_pending(v, port);
-}
-
-int guest_enabled_event(struct vcpu *v, int virq)
-{
- int port;
-
- if ( unlikely(v == NULL) )
- return 0;
-
- port = v->virq_to_evtchn[virq];
- if ( port == 0 )
- return 0;
-
- /* virq is in use */
- return 1;
+
+ out:
+ spin_unlock_irqrestore(&v->virq_lock, flags);
}
void send_guest_global_virq(struct domain *d, int virq)
{
+ unsigned long flags;
int port;
struct vcpu *v;
struct evtchn *chn;
@@ -617,20 +620,28 @@ void send_guest_global_virq(struct domai
if ( unlikely(v == NULL) )
return;
+ spin_lock_irqsave(&v->virq_lock, flags);
+
port = v->virq_to_evtchn[virq];
if ( unlikely(port == 0) )
- return;
+ goto out;
chn = evtchn_from_port(d, port);
evtchn_set_pending(d->vcpu[chn->notify_vcpu_id], port);
-}
-
+
+ out:
+ spin_unlock_irqrestore(&v->virq_lock, flags);
+}
int send_guest_pirq(struct domain *d, int pirq)
{
int port = d->pirq_to_evtchn[pirq];
struct evtchn *chn;
+ /*
+ * It should not be possible to race with __evtchn_close():
+ * The caller of this function must synchronise with pirq_guest_unbind().
+ */
ASSERT(port != 0);
chn = evtchn_from_port(d, port);
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/include/xen/irq.h
--- a/xen/include/xen/irq.h Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/include/xen/irq.h Thu Jul 31 11:13:30 2008 +0100
@@ -78,7 +78,7 @@ extern int pirq_guest_eoi(struct domain
extern int pirq_guest_eoi(struct domain *d, int irq);
extern int pirq_guest_unmask(struct domain *d);
extern int pirq_guest_bind(struct vcpu *v, int irq, int will_share);
-extern int pirq_guest_unbind(struct domain *d, int irq);
+extern void pirq_guest_unbind(struct domain *d, int irq);
static inline void set_native_irq_info(int irq, cpumask_t mask)
{
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/include/xen/sched.h Thu Jul 31 11:13:30 2008 +0100
@@ -137,7 +137,9 @@ struct vcpu
unsigned long pause_flags;
atomic_t pause_count;
+ /* IRQ-safe virq_lock protects against delivering VIRQ to stale evtchn. */
u16 virq_to_evtchn[NR_VIRQS];
+ spinlock_t virq_lock;
/* Bitmask of CPUs on which this VCPU may run. */
cpumask_t cpu_affinity;
diff -r 82edb8c9ae17 -r 482c16b55c28 xen/include/xen/spinlock.h
--- a/xen/include/xen/spinlock.h Thu Jul 31 09:51:06 2008 +0100
+++ b/xen/include/xen/spinlock.h Thu Jul 31 11:13:30 2008 +0100
@@ -85,8 +85,8 @@ typedef struct { int gcc_is_buggy; } rwl
/* Ensure a lock is quiescent between two critical operations. */
static inline void spin_barrier(spinlock_t *lock)
{
- spin_lock(lock);
- spin_unlock(lock);
+ do { mb(); } while ( spin_is_locked(lock) );
+ mb();
}
#define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED
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