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Subject[PATCH 5/6] KVM: x86: prevent setup of invalid routes
Date
The check in kvm_set_pic_irq() and kvm_set_ioapic_irq() was just a
temporary measure until the code improved enough for us to do this.

This changes APIC in a case when KVM_SET_GSI_ROUTING is called to set up pic
and ioapic routes before KVM_CREATE_IRQCHIP. Those rules would get overwritten
by KVM_CREATE_IRQCHIP at best, so it is pointless to allow it. Userspaces
hopefully noticed that things don't work if they do that and don't do that.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/irq_comm.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 913e054a68e9..2838c0c37279 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -41,15 +41,6 @@ static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
bool line_status)
{
struct kvm_pic *pic = pic_irqchip(kvm);
-
- /*
- * XXX: rejecting pic routes when pic isn't in use would be better,
- * but the default routing table is installed while kvm->arch.vpic is
- * NULL and KVM_CREATE_IRQCHIP can race with KVM_IRQ_LINE.
- */
- if (!pic)
- return -1;
-
return kvm_pic_set_irq(pic, e->irqchip.pin, irq_source_id, level);
}

@@ -58,10 +49,6 @@ static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e,
bool line_status)
{
struct kvm_ioapic *ioapic = kvm->arch.vioapic;
-
- if (!ioapic)
- return -1;
-
return kvm_ioapic_set_irq(ioapic, e->irqchip.pin, irq_source_id, level,
line_status);
}
@@ -293,10 +280,16 @@ int kvm_set_routing_entry(struct kvm *kvm,
delta = 8;
/* fall through */
case KVM_IRQCHIP_PIC_MASTER:
+ if (!pic_in_kernel(kvm))
+ goto out;
+
e->set = kvm_set_pic_irq;
max_pin = PIC_NUM_PINS;
break;
case KVM_IRQCHIP_IOAPIC:
+ if (!ioapic_in_kernel(kvm))
+ goto out;
+
max_pin = KVM_IOAPIC_NUM_PINS;
e->set = kvm_set_ioapic_irq;
break;
--
2.10.2
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