kvm: i386: Add classic PCI device assignment

This adds PCI device assignment for i386 targets using the classic KVM
interfaces. This version is 100% identical to what is being maintained
in qemu-kvm for several years and is supported by libvirt as well. It is
expected to remain relevant for another couple of years until kernels
without full-features and performance-wise equivalent VFIO support are
obsolete.

A refactoring to-do that should be done in-tree is to model MSI and
MSI-X support via the generic PCI layer, similar to what VFIO is already
doing for MSI-X. This should improve the correctness and clean up the
code from duplicate logic.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

hw/kvm/Makefile.objs

@@ -1 +1 @@
-obj-$(CONFIG_KVM) += clock.o apic.o i8259.o ioapic.o i8254.o
+obj-$(CONFIG_KVM) += clock.o apic.o i8259.o ioapic.o i8254.o pci-assign.o

hw/qdev-monitor.c

@@ -44,6 +44,7 @@ static const QDevAlias qdev_alias_table[] = {
     { "virtio-serial-s390", "virtio-serial", QEMU_ARCH_S390X },
     { "lsi53c895a", "lsi" },
     { "ich9-ahci", "ahci" },
+    { "kvm-pci-assign", "pci-assign" },
     { }
 };