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, 36 insertions, 0 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 786a3ae373b0..c65484b471c6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -843,6 +843,7 @@ static struct kvm *kvm_create_vm(void)
         if (IS_ERR(kvm))
                 goto out;
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
+        INIT_LIST_HEAD(&kvm->irq_routing);
         INIT_HLIST_HEAD(&kvm->mask_notifier_list);
 #endif
 
@@ -926,6 +927,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
         spin_lock(&kvm_lock);
         list_del(&kvm->vm_list);
         spin_unlock(&kvm_lock);
+        kvm_free_irq_routing(kvm);
         kvm_io_bus_destroy(&kvm->pio_bus);
         kvm_io_bus_destroy(&kvm->mmio_bus);
 #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
@@ -1946,6 +1948,36 @@ static long kvm_vm_ioctl(struct file *filp,
                 break;
         }
 #endif
+#ifdef KVM_CAP_IRQ_ROUTING
+        case KVM_SET_GSI_ROUTING: {
+                struct kvm_irq_routing routing;
+                struct kvm_irq_routing __user *urouting;
+                struct kvm_irq_routing_entry *entries;
+
+                r = -EFAULT;
+                if (copy_from_user(&routing, argp, sizeof(routing)))
+                        goto out;
+                r = -EINVAL;
+                if (routing.nr >= KVM_MAX_IRQ_ROUTES)
+                        goto out;
+                if (routing.flags)
+                        goto out;
+                r = -ENOMEM;
+                entries = vmalloc(routing.nr * sizeof(*entries));
+                if (!entries)
+                        goto out;
+                r = -EFAULT;
+                urouting = argp;
+                if (copy_from_user(entries, urouting->entries,
+                                   routing.nr * sizeof(*entries)))
+                        goto out_free_irq_routing;
+                r = kvm_set_irq_routing(kvm, entries, routing.nr,
+                                        routing.flags);
+        out_free_irq_routing:
+                vfree(entries);
+                break;
+        }
+#endif
         default:
                 r = kvm_arch_vm_ioctl(filp, ioctl, arg);
         }
@@ -2012,6 +2044,10 @@ static long kvm_dev_ioctl_check_extension_generic(long arg)
         case KVM_CAP_USER_MEMORY:
         case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
                 return 1;
+#ifdef CONFIG_HAVE_KVM_IRQCHIP
+        case KVM_CAP_IRQ_ROUTING:
+                return 1;
+#endif
         default:
                 break;
         }