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x86/IRQ: reduce casting involved in guest action retrieval
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Introduce a helper function covering both the IRQ_GUEST check and the
cast involved in obtaining the (correctly typed) pointer. Where possible
add const and/or reduce variable scope.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
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@jbeulich
jbeulich committed Dec 4, 2020
1 parent bfc78f7 commit a00b271
Showing 1 changed file with 31 additions and 45 deletions.
76 changes: 31 additions & 45 deletions xen/arch/x86/irq.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1042,6 +1042,11 @@ typedef struct {
struct domain *guest[IRQ_MAX_GUESTS];
} irq_guest_action_t;

static irq_guest_action_t *guest_action(const struct irq_desc *desc)
{
return desc->status & IRQ_GUEST ? (void *)desc->action : NULL;
}

/*
* Stack of interrupts awaiting EOI on each CPU. These must be popped in
* order, as only the current highest-priority pending irq can be EOIed.
Expand Down Expand Up @@ -1111,11 +1116,9 @@ static void irq_guest_eoi_timer_fn(void *data)

spin_lock_irq(&desc->lock);

if ( !(desc->status & IRQ_GUEST) )
if ( !(action = guest_action(desc)) )
goto out;

action = (irq_guest_action_t *)desc->action;

ASSERT(action->ack_type != ACKTYPE_NONE);

/*
Expand Down Expand Up @@ -1351,16 +1354,15 @@ static void flush_ready_eoi(void)
pending_eoi_sp(peoi) = sp+1;
}

static void __set_eoi_ready(struct irq_desc *desc)
static void __set_eoi_ready(const struct irq_desc *desc)
{
irq_guest_action_t *action = (irq_guest_action_t *)desc->action;
irq_guest_action_t *action = guest_action(desc);
struct pending_eoi *peoi = this_cpu(pending_eoi);
int irq, sp;

irq = desc - irq_desc;

if ( !(desc->status & IRQ_GUEST) ||
(action->in_flight != 0) ||
if ( !action || action->in_flight ||
!cpumask_test_and_clear_cpu(smp_processor_id(),
action->cpu_eoi_map) )
return;
Expand Down Expand Up @@ -1400,18 +1402,11 @@ void pirq_guest_eoi(struct pirq *pirq)

void desc_guest_eoi(struct irq_desc *desc, struct pirq *pirq)
{
irq_guest_action_t *action;
irq_guest_action_t *action = guest_action(desc);
cpumask_t cpu_eoi_map;

if ( !(desc->status & IRQ_GUEST) )
{
spin_unlock_irq(&desc->lock);
return;
}

action = (irq_guest_action_t *)desc->action;

if ( unlikely(!test_and_clear_bool(pirq->masked)) ||
if ( unlikely(!action) ||
unlikely(!test_and_clear_bool(pirq->masked)) ||
unlikely(--action->in_flight != 0) )
{
spin_unlock_irq(&desc->lock);
Expand Down Expand Up @@ -1510,17 +1505,17 @@ static int irq_acktype(const struct irq_desc *desc)

int pirq_shared(struct domain *d, int pirq)
{
struct irq_desc *desc;
irq_guest_action_t *action;
struct irq_desc *desc;
const irq_guest_action_t *action;
unsigned long flags;
int shared;

desc = domain_spin_lock_irq_desc(d, pirq, &flags);
if ( desc == NULL )
return 0;

action = (irq_guest_action_t *)desc->action;
shared = ((desc->status & IRQ_GUEST) && (action->nr_guests > 1));
action = guest_action(desc);
shared = (action && (action->nr_guests > 1));

spin_unlock_irqrestore(&desc->lock, flags);

Expand All @@ -1544,9 +1539,7 @@ int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share)
goto out;
}

action = (irq_guest_action_t *)desc->action;

if ( !(desc->status & IRQ_GUEST) )
if ( !(action = guest_action(desc)) )
{
if ( desc->action != NULL )
{
Expand Down Expand Up @@ -1659,21 +1652,18 @@ int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share)
static irq_guest_action_t *__pirq_guest_unbind(
struct domain *d, struct pirq *pirq, struct irq_desc *desc)
{
irq_guest_action_t *action;
irq_guest_action_t *action = guest_action(desc);
cpumask_t cpu_eoi_map;
int i;

action = (irq_guest_action_t *)desc->action;

if ( unlikely(action == NULL) )
{
dprintk(XENLOG_G_WARNING, "dom%d: pirq %d: desc->action is NULL!\n",
d->domain_id, pirq->pirq);
BUG_ON(!(desc->status & IRQ_GUEST));
return NULL;
}

BUG_ON(!(desc->status & IRQ_GUEST));

for ( i = 0; (i < action->nr_guests) && (action->guest[i] != d); i++ )
continue;
BUG_ON(i == action->nr_guests);
Expand Down Expand Up @@ -1793,14 +1783,12 @@ static bool pirq_guest_force_unbind(struct domain *d, struct pirq *pirq)
desc = pirq_spin_lock_irq_desc(pirq, NULL);
BUG_ON(desc == NULL);

if ( !(desc->status & IRQ_GUEST) )
goto out;

action = (irq_guest_action_t *)desc->action;
action = guest_action(desc);
if ( unlikely(action == NULL) )
{
dprintk(XENLOG_G_WARNING, "dom%d: pirq %d: desc->action is NULL!\n",
d->domain_id, pirq->pirq);
if ( desc->status & IRQ_GUEST )
dprintk(XENLOG_G_WARNING, "%pd: pirq %d: desc->action is NULL!\n",
d, pirq->pirq);
goto out;
}

Expand All @@ -1827,7 +1815,7 @@ static bool pirq_guest_force_unbind(struct domain *d, struct pirq *pirq)

static void do_IRQ_guest(struct irq_desc *desc, unsigned int vector)
{
irq_guest_action_t *action = (irq_guest_action_t *)desc->action;
irq_guest_action_t *action = guest_action(desc);
unsigned int i;
struct pending_eoi *peoi = this_cpu(pending_eoi);

Expand Down Expand Up @@ -2444,7 +2432,6 @@ static void dump_irqs(unsigned char key)
{
int i, irq, pirq;
struct irq_desc *desc;
irq_guest_action_t *action;
struct domain *d;
const struct pirq *info;
unsigned long flags;
Expand All @@ -2454,6 +2441,8 @@ static void dump_irqs(unsigned char key)

for ( irq = 0; irq < nr_irqs; irq++ )
{
const irq_guest_action_t *action;

if ( !(irq & 0x1f) )
process_pending_softirqs();

Expand All @@ -2473,10 +2462,9 @@ static void dump_irqs(unsigned char key)
if ( ssid )
printk("Z=%-25s ", ssid);

if ( desc->status & IRQ_GUEST )
action = guest_action(desc);
if ( action )
{
action = (irq_guest_action_t *)desc->action;

printk("in-flight=%d%c",
action->in_flight, action->nr_guests ? ' ' : '\n');

Expand Down Expand Up @@ -2651,17 +2639,15 @@ void fixup_irqs(const cpumask_t *mask, bool verbose)
void fixup_eoi(void)
{
unsigned int irq, sp;
struct irq_desc *desc;
irq_guest_action_t *action;
struct pending_eoi *peoi;

/* Clean up cpu_eoi_map of every interrupt to exclude this CPU. */
for ( irq = 0; irq < nr_irqs; irq++ )
{
desc = irq_to_desc(irq);
if ( !(desc->status & IRQ_GUEST) )
irq_guest_action_t *action = guest_action(irq_to_desc(irq));

if ( !action )
continue;
action = (irq_guest_action_t *)desc->action;
cpumask_clear_cpu(smp_processor_id(), action->cpu_eoi_map);
}

Expand Down

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