arch/x86/kvm/i8259.c

Source file repositories/reference/linux-study-clean/arch/x86/kvm/i8259.c

File Facts

System
Linux kernel
Corpus path
arch/x86/kvm/i8259.c
Extension
.c
Size
14868 bytes
Lines
656
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

kvm_for_each_vcpu(i, vcpu, s->kvm) {
			if (kvm_apic_accept_pic_intr(vcpu)) {
				kvm_make_request(KVM_REQ_EVENT, vcpu);
				kvm_vcpu_kick(vcpu);
				return;
			}
		}
	}
}

static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
{
	s->isr &= ~(1 << irq);
	if (s != &s->pics_state->pics[0])
		irq += 8;
	/*
	 * We are dropping lock while calling ack notifiers since ack
	 * notifier callbacks for assigned devices call into PIC recursively.
	 * Other interrupt may be delivered to PIC while lock is dropped but
	 * it should be safe since PIC state is already updated at this stage.
	 */
	pic_unlock(s->pics_state);
	kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
	pic_lock(s->pics_state);
}

/*
 * set irq level. If an edge is detected, then the IRR is set to 1
 */
static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level)
{
	int mask, ret = 1;
	mask = 1 << irq;
	if (s->elcr & mask)	/* level triggered */
		if (level) {
			ret = !(s->irr & mask);
			s->irr |= mask;
			s->last_irr |= mask;
		} else {
			s->irr &= ~mask;
			s->last_irr &= ~mask;
		}
	else	/* edge triggered */
		if (level) {
			if ((s->last_irr & mask) == 0) {
				ret = !(s->irr & mask);
				s->irr |= mask;
			}
			s->last_irr |= mask;
		} else
			s->last_irr &= ~mask;

	return (s->imr & mask) ? -1 : ret;
}

/*
 * return the highest priority found in mask (highest = smallest
 * number). Return 8 if no irq
 */
static inline int get_priority(struct kvm_kpic_state *s, int mask)
{
	int priority;
	if (mask == 0)
		return 8;
	priority = 0;
	while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0)
		priority++;
	return priority;
}

/*
 * return the pic wanted interrupt. return -1 if none
 */
static int pic_get_irq(struct kvm_kpic_state *s)
{
	int mask, cur_priority, priority;

	mask = s->irr & ~s->imr;
	priority = get_priority(s, mask);
	if (priority == 8)
		return -1;
	/*
	 * compute current priority. If special fully nested mode on the
	 * master, the IRQ coming from the slave is not taken into account
	 * for the priority computation.
	 */
	mask = s->isr;
	if (s->special_fully_nested_mode && s == &s->pics_state->pics[0])
		mask &= ~(1 << 2);
	cur_priority = get_priority(s, mask);

Annotation

Implementation Notes