KVM: Userspace controlled irq routing

Currently KVM has a static routing from GSI numbers to interrupts (namely,
0-15 are mapped 1:1 to both PIC and IOAPIC, and 16:23 are mapped 1:1 to
the IOAPIC).  This is insufficient for several reasons:

- HPET requires non 1:1 mapping for the timer interrupt
- MSIs need a new method to assign interrupt numbers and dispatch them
- ACPI APIC mode needs to be able to reassign the PCI LINK interrupts to the
  ioapics

This patch implements an interrupt routing table (as a linked list, but this
can be easily changed) and a userspace interface to replace the table.  The
routing table is initialized according to the current hardwired mapping.

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 141a0166e51c..32e3a7ec6ad2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1835,6 +1835,12 @@ long kvm_arch_vm_ioctl(struct file *filp,
                         }
                 } else
                         goto out;
+                r = kvm_setup_default_irq_routing(kvm);
+                if (r) {
+                        kfree(kvm->arch.vpic);
+                        kfree(kvm->arch.vioapic);
+                        goto out;
+                }
                 break;
         case KVM_CREATE_PIT:
                 mutex_lock(&kvm->lock);