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KVM: ioapic: fix lost interrupt when changing a device's irq 

The ioapic acknowledge path translates interrupt vectors to irqs.  It
currently uses a first match algorithm, stopping when it finds the first
redirection table entry containing the vector.  That fails however if the
guest changes the irq to a different line, leaving the old redirection table
entry in place (though masked).  Result is interrupts not making it to the
guest.

Fix by always scanning the entire redirection table.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2008-06-17 15:36:36 -07:00
parent 6bf6a9532f
commit 4fa6b9c5dc
1 changed files with 11 additions and 20 deletions
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31
virt/kvm/ioapic.c
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@ -269,28 +269,9 @@ void kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level)
}
}
static int get_eoi_gsi(struct kvm_ioapic *ioapic, int vector)
static void __kvm_ioapic_update_eoi(struct kvm_ioapic *ioapic, int gsi)
{
int i;
for (i = 0; i < IOAPIC_NUM_PINS; i++)
if (ioapic->redirtbl[i].fields.vector == vector)
return i;
return -1;
}
void kvm_ioapic_update_eoi(struct kvm *kvm, int vector)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
union ioapic_redir_entry *ent;
int gsi;
gsi = get_eoi_gsi(ioapic, vector);
if (gsi == -1) {
printk(KERN_WARNING "Can't find redir item for %d EOI\n",
vector);
return;
}
ent = &ioapic->redirtbl[gsi];
ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG);
@ -300,6 +281,16 @@ void kvm_ioapic_update_eoi(struct kvm *kvm, int vector)
ioapic_deliver(ioapic, gsi);
}
void kvm_ioapic_update_eoi(struct kvm *kvm, int vector)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
int i;
for (i = 0; i < IOAPIC_NUM_PINS; i++)
if (ioapic->redirtbl[i].fields.vector == vector)
__kvm_ioapic_update_eoi(ioapic, i);
}
static int ioapic_in_range(struct kvm_io_device *this, gpa_t addr)
{
struct kvm_ioapic *ioapic = (struct kvm_ioapic *)this->private;