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evtchn: convert per-channel lock to be IRQ-safe

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... in order for send_guest_{global,vcpu}_virq() to be able to make use
of it.

This is part of XSA-343.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
This commit is contained in:
Jan Beulich committed 2020-09-22 15:51:28 +02:00
1 parent 8d385b247b
commit c0ddc86348
1 file changed
+44 -29
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xen/common/event_channel.c
+44 -29
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@@ -248,6 +248,7 @@ static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
int port;
domid_t dom = alloc->dom;
long rc;
unsigned long flags;
d = rcu_lock_domain_by_any_id(dom);
if ( d == NULL )
@@ -263,14 +264,14 @@ static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
if ( rc )
goto out;
spin_lock(&chn->lock);
spin_lock_irqsave(&chn->lock, flags);
chn->state = ECS_UNBOUND;
if ( (chn->u.unbound.remote_domid = alloc->remote_dom) == DOMID_SELF )
chn->u.unbound.remote_domid = current->domain->domain_id;
evtchn_port_init(d, chn);
spin_unlock(&chn->lock);
spin_unlock_irqrestore(&chn->lock, flags);
alloc->port = port;
@@ -283,26 +284,32 @@ static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
}
static void double_evtchn_lock(struct evtchn *lchn, struct evtchn *rchn)
static unsigned long double_evtchn_lock(struct evtchn *lchn,
struct evtchn *rchn)
{
if ( lchn < rchn )
unsigned long flags;
if ( lchn <= rchn )
{
spin_lock(&lchn->lock);
spin_lock(&rchn->lock);
spin_lock_irqsave(&lchn->lock, flags);
if ( lchn != rchn )
spin_lock(&rchn->lock);
}
else
{
if ( lchn != rchn )
spin_lock(&rchn->lock);
spin_lock_irqsave(&rchn->lock, flags);
spin_lock(&lchn->lock);
}
return flags;
}
static void double_evtchn_unlock(struct evtchn *lchn, struct evtchn *rchn)
static void double_evtchn_unlock(struct evtchn *lchn, struct evtchn *rchn,
unsigned long flags)
{
spin_unlock(&lchn->lock);
if ( lchn != rchn )
spin_unlock(&rchn->lock);
spin_unlock(&lchn->lock);
spin_unlock_irqrestore(&rchn->lock, flags);
}
static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
@@ -312,6 +319,7 @@ static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
int lport, rport = bind->remote_port;
domid_t rdom = bind->remote_dom;
long rc;
unsigned long flags;
if ( rdom == DOMID_SELF )
rdom = current->domain->domain_id;
@@ -347,7 +355,7 @@ static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
if ( rc )
goto out;
double_evtchn_lock(lchn, rchn);
flags = double_evtchn_lock(lchn, rchn);
lchn->u.interdomain.remote_dom = rd;
lchn->u.interdomain.remote_port = rport;
@@ -364,7 +372,7 @@ static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
*/
evtchn_port_set_pending(ld, lchn->notify_vcpu_id, lchn);
double_evtchn_unlock(lchn, rchn);
double_evtchn_unlock(lchn, rchn, flags);
bind->local_port = lport;
@@ -387,6 +395,7 @@ int evtchn_bind_virq(evtchn_bind_virq_t *bind, evtchn_port_t port)
struct domain *d = current->domain;
int virq = bind->virq, vcpu = bind->vcpu;
int rc = 0;
unsigned long flags;
if ( (virq < 0) || (virq >= ARRAY_SIZE(v->virq_to_evtchn)) )
return -EINVAL;
@@ -424,14 +433,14 @@ int evtchn_bind_virq(evtchn_bind_virq_t *bind, evtchn_port_t port)
chn = evtchn_from_port(d, port);
spin_lock(&chn->lock);
spin_lock_irqsave(&chn->lock, flags);
chn->state = ECS_VIRQ;
chn->notify_vcpu_id = vcpu;
chn->u.virq = virq;
evtchn_port_init(d, chn);
spin_unlock(&chn->lock);
spin_unlock_irqrestore(&chn->lock, flags);
v->virq_to_evtchn[virq] = bind->port = port;
@@ -448,6 +457,7 @@ static long evtchn_bind_ipi(evtchn_bind_ipi_t *bind)
struct domain *d = current->domain;
int port, vcpu = bind->vcpu;
long rc = 0;
unsigned long flags;
if ( domain_vcpu(d, vcpu) == NULL )
return -ENOENT;
@@ -459,13 +469,13 @@ static long evtchn_bind_ipi(evtchn_bind_ipi_t *bind)
chn = evtchn_from_port(d, port);
spin_lock(&chn->lock);
spin_lock_irqsave(&chn->lock, flags);
chn->state = ECS_IPI;
chn->notify_vcpu_id = vcpu;
evtchn_port_init(d, chn);
spin_unlock(&chn->lock);
spin_unlock_irqrestore(&chn->lock, flags);
bind->port = port;
@@ -509,6 +519,7 @@ static long evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
struct pirq *info;
int port = 0, pirq = bind->pirq;
long rc;
unsigned long flags;
if ( (pirq < 0) || (pirq >= d->nr_pirqs) )
return -EINVAL;
@@ -541,14 +552,14 @@ static long evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
goto out;
}
spin_lock(&chn->lock);
spin_lock_irqsave(&chn->lock, flags);
chn->state = ECS_PIRQ;
chn->u.pirq.irq = pirq;
link_pirq_port(port, chn, v);
evtchn_port_init(d, chn);
spin_unlock(&chn->lock);
spin_unlock_irqrestore(&chn->lock, flags);
bind->port = port;
@@ -569,6 +580,7 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
struct evtchn *chn1, *chn2;
int port2;
long rc = 0;
unsigned long flags;
again:
spin_lock(&d1->event_lock);
@@ -668,14 +680,14 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
BUG_ON(chn2->state != ECS_INTERDOMAIN);
BUG_ON(chn2->u.interdomain.remote_dom != d1);
double_evtchn_lock(chn1, chn2);
flags = double_evtchn_lock(chn1, chn2);
evtchn_free(d1, chn1);
chn2->state = ECS_UNBOUND;
chn2->u.unbound.remote_domid = d1->domain_id;
double_evtchn_unlock(chn1, chn2);
double_evtchn_unlock(chn1, chn2, flags);
goto out;
@@ -683,9 +695,9 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
BUG();
}
spin_lock(&chn1->lock);
spin_lock_irqsave(&chn1->lock, flags);
evtchn_free(d1, chn1);
spin_unlock(&chn1->lock);
spin_unlock_irqrestore(&chn1->lock, flags);
out:
if ( d2 != NULL )
@@ -705,13 +717,14 @@ int evtchn_send(struct domain *ld, unsigned int lport)
struct evtchn *lchn, *rchn;
struct domain *rd;
int rport, ret = 0;
unsigned long flags;
if ( !port_is_valid(ld, lport) )
return -EINVAL;
lchn = evtchn_from_port(ld, lport);
spin_lock(&lchn->lock);
spin_lock_irqsave(&lchn->lock, flags);
/* Guest cannot send via a Xen-attached event channel. */
if ( unlikely(consumer_is_xen(lchn)) )
@@ -746,7 +759,7 @@ int evtchn_send(struct domain *ld, unsigned int lport)
}
out:
spin_unlock(&lchn->lock);
spin_unlock_irqrestore(&lchn->lock, flags);
return ret;
}
@@ -1238,6 +1251,7 @@ int alloc_unbound_xen_event_channel(
{
struct evtchn *chn;
int port, rc;
unsigned long flags;
spin_lock(&ld->event_lock);
@@ -1250,14 +1264,14 @@ int alloc_unbound_xen_event_channel(
if ( rc )
goto out;
spin_lock(&chn->lock);
spin_lock_irqsave(&chn->lock, flags);
chn->state = ECS_UNBOUND;
chn->xen_consumer = get_xen_consumer(notification_fn);
chn->notify_vcpu_id = lvcpu;
chn->u.unbound.remote_domid = remote_domid;
spin_unlock(&chn->lock);
spin_unlock_irqrestore(&chn->lock, flags);
write_atomic(&ld->xen_evtchns, ld->xen_evtchns + 1);
@@ -1280,11 +1294,12 @@ void notify_via_xen_event_channel(struct domain *ld, int lport)
{
struct evtchn *lchn, *rchn;
struct domain *rd;
unsigned long flags;
ASSERT(port_is_valid(ld, lport));
lchn = evtchn_from_port(ld, lport);
spin_lock(&lchn->lock);
spin_lock_irqsave(&lchn->lock, flags);
if ( likely(lchn->state == ECS_INTERDOMAIN) )
{
@@ -1294,7 +1309,7 @@ void notify_via_xen_event_channel(struct domain *ld, int lport)
evtchn_port_set_pending(rd, rchn->notify_vcpu_id, rchn);
}
spin_unlock(&lchn->lock);
spin_unlock_irqrestore(&lchn->lock, flags);
}
void evtchn_check_pollers(struct domain *d, unsigned int port)
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