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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v10 10/10] xen/arm: make accesses to desc->status flags atomic
This way we don't need to take the desc->lock in order to access
desc->status in many of the gic and vgic functions.
Using *_bit manipulation functions on desc->status is safe on arm64:
status is an unsigned int but is the first field of a struct that
contains pointers, therefore the alignement of the struct is at least 8
bytes.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
Changes in v10:
- add in-code comment;
- fix _IRQF_SHARED renaming.
Changes in v2:
- rebase on ab78724fc5628318b172b4344f7280621a151e1b.
---
xen/arch/arm/gic-v2.c | 4 ++--
xen/arch/arm/gic.c | 6 +++---
xen/arch/arm/irq.c | 33 +++++++++++++++++----------------
xen/include/xen/irq.h | 5 +++++
4 files changed, 27 insertions(+), 21 deletions(-)
diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index da60a41..78ad4de 100644
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -516,7 +516,7 @@ static void gicv2_irq_enable(struct irq_desc *desc)
ASSERT(spin_is_locked(&desc->lock));
spin_lock_irqsave(&gicv2.lock, flags);
- desc->status &= ~IRQ_DISABLED;
+ clear_bit(_IRQ_DISABLED, &desc->status);
dsb(sy);
/* Enable routing */
writel_gicd((1u << (irq % 32)), GICD_ISENABLER + (irq / 32) * 4);
@@ -533,7 +533,7 @@ static void gicv2_irq_disable(struct irq_desc *desc)
spin_lock_irqsave(&gicv2.lock, flags);
/* Disable routing */
writel_gicd(1u << (irq % 32), GICD_ICENABLER + (irq / 32) * 4);
- desc->status |= IRQ_DISABLED;
+ set_bit(_IRQ_DISABLED, &desc->status);
spin_unlock_irqrestore(&gicv2.lock, flags);
}
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 2aa9500..6611ba0 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -115,7 +115,7 @@ void gic_route_irq_to_xen(struct irq_desc *desc, const
cpumask_t *cpu_mask,
{
ASSERT(priority <= 0xff); /* Only 8 bits of priority */
ASSERT(desc->irq < gic_number_lines());/* Can't route interrupts that
don't exist */
- ASSERT(desc->status & IRQ_DISABLED);
+ ASSERT(test_bit(_IRQ_DISABLED, &desc->status));
ASSERT(spin_is_locked(&desc->lock));
desc->handler = gic_hw_ops->gic_host_irq_type;
@@ -133,7 +133,7 @@ void gic_route_irq_to_guest(struct domain *d, struct
irq_desc *desc,
ASSERT(spin_is_locked(&desc->lock));
desc->handler = gic_hw_ops->gic_guest_irq_type;
- desc->status |= IRQ_GUEST;
+ set_bit(_IRQ_GUEST, &desc->status);
gic_set_irq_properties(desc, cpumask_of(smp_processor_id()), GIC_PRI_IRQ);
@@ -369,7 +369,7 @@ static void gic_update_one_lr(struct vcpu *v, int i)
if ( p->desc != NULL )
{
- p->desc->status &= ~IRQ_INPROGRESS;
+ clear_bit(_IRQ_INPROGRESS, &p->desc->status);
if ( platform_has_quirk(PLATFORM_QUIRK_GUEST_PIRQ_NEED_EOI) )
gic_hw_ops->deactivate_irq(p->desc);
}
diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 7150c7a..25ecf1d 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -126,7 +126,7 @@ static inline struct domain *irq_get_domain(struct irq_desc
*desc)
{
ASSERT(spin_is_locked(&desc->lock));
- if ( !(desc->status & IRQ_GUEST) )
+ if ( !test_bit(_IRQ_GUEST, &desc->status) )
return dom_xen;
ASSERT(desc->action != NULL);
@@ -195,13 +195,13 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq,
int is_fiq)
goto out;
}
- if ( desc->status & IRQ_GUEST )
+ if ( test_bit(_IRQ_GUEST, &desc->status) )
{
struct domain *d = irq_get_domain(desc);
desc->handler->end(desc);
- desc->status |= IRQ_INPROGRESS;
+ set_bit(_IRQ_INPROGRESS, &desc->status);
desc->arch.eoi_cpu = smp_processor_id();
/* the irq cannot be a PPI, we only support delivery of SPIs to
@@ -210,22 +210,23 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq,
int is_fiq)
goto out_no_end;
}
- desc->status |= IRQ_PENDING;
+ set_bit(_IRQ_PENDING, &desc->status);
/*
* Since we set PENDING, if another processor is handling a different
* instance of this same irq, the other processor will take care of it.
*/
- if ( desc->status & (IRQ_DISABLED | IRQ_INPROGRESS) )
+ if ( test_bit(_IRQ_DISABLED, &desc->status) ||
+ test_bit(_IRQ_INPROGRESS, &desc->status) )
goto out;
- desc->status |= IRQ_INPROGRESS;
+ set_bit(_IRQ_INPROGRESS, &desc->status);
- while ( desc->status & IRQ_PENDING )
+ while ( test_bit(_IRQ_PENDING, &desc->status) )
{
struct irqaction *action;
- desc->status &= ~IRQ_PENDING;
+ clear_bit(_IRQ_PENDING, &desc->status);
action = desc->action;
spin_unlock_irq(&desc->lock);
@@ -239,7 +240,7 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq,
int is_fiq)
spin_lock_irq(&desc->lock);
}
- desc->status &= ~IRQ_INPROGRESS;
+ clear_bit(_IRQ_INPROGRESS, &desc->status);
out:
desc->handler->end(desc);
@@ -282,13 +283,13 @@ void release_irq(unsigned int irq, const void *dev_id)
if ( !desc->action )
{
desc->handler->shutdown(desc);
- desc->status &= ~IRQ_GUEST;
+ clear_bit(_IRQ_GUEST, &desc->status);
}
spin_unlock_irqrestore(&desc->lock,flags);
/* Wait to make sure it's not being used on another CPU */
- do { smp_mb(); } while ( desc->status & IRQ_INPROGRESS );
+ do { smp_mb(); } while ( test_bit(_IRQ_INPROGRESS, &desc->status) );
if ( action->free_on_release )
xfree(action);
@@ -305,13 +306,13 @@ static int __setup_irq(struct irq_desc *desc, unsigned
int irqflags,
* - if the IRQ is marked as shared
* - dev_id is not NULL when IRQF_SHARED is set
*/
- if ( desc->action != NULL && (!(desc->status & IRQF_SHARED) || !shared) )
+ if ( desc->action != NULL && (!test_bit(_IRQF_SHARED, &desc->status) ||
!shared) )
return -EINVAL;
if ( shared && new->dev_id == NULL )
return -EINVAL;
if ( shared )
- desc->status |= IRQF_SHARED;
+ set_bit(_IRQF_SHARED, &desc->status);
new->next = desc->action;
dsb(ish);
@@ -332,7 +333,7 @@ int setup_irq(unsigned int irq, unsigned int irqflags,
struct irqaction *new)
spin_lock_irqsave(&desc->lock, flags);
- if ( desc->status & IRQ_GUEST )
+ if ( test_bit(_IRQ_GUEST, &desc->status) )
{
struct domain *d = irq_get_domain(desc);
@@ -396,10 +397,10 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
{
struct domain *ad = irq_get_domain(desc);
- if ( (desc->status & IRQ_GUEST) && d == ad )
+ if ( test_bit(_IRQ_GUEST, &desc->status) && d == ad )
goto out;
- if ( desc->status & IRQ_GUEST )
+ if ( test_bit(_IRQ_GUEST, &desc->status) )
printk(XENLOG_ERR "ERROR: IRQ %u is already used by domain %u\n",
irq, ad->domain_id);
else
diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index 96d818f..ffb5932 100644
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -76,6 +76,11 @@ struct msi_desc;
* This is the "IRQ descriptor", which contains various information
* about the irq, including what kind of hardware handling it has,
* whether it is disabled etc etc.
+ *
+ * Note: on ARMv8 we can use normal bit manipulation functions to access
+ * the status field because struct irq_desc contains pointers, therefore
+ * the alignment of the struct is at least 8 bytes and status is the
+ * first field.
*/
typedef struct irq_desc {
unsigned int status; /* IRQ status */
--
1.7.10.4
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