tree aef5ce861803c98a609b8ffc8207380988fb1eb5
parent 45bd4b1c099843565e1686f09ae307984a08a3d6
author Dou Liyang <douly.fnst@cn.fujitsu.com> 1510626841 +0800
committer Michael S. Tsirkin <mst@redhat.com> 1510847213 +0200

NUMA: Enable adding NUMA node implicitly

Linux and Windows need ACPI SRAT table to make memory hotplug work properly,
however currently QEMU doesn't create SRAT table if numa options aren't present
on CLI.

Which breaks both linux and windows guests in certain conditions:
 * Windows: won't enable memory hotplug without SRAT table at all
 * Linux: if QEMU is started with initial memory all below 4Gb and no SRAT table
   present, guest kernel will use nommu DMA ops, which breaks 32bit hw drivers
   when memory is hotplugged and guest tries to use it with that drivers.

Fix above issues by automatically creating a numa node when QEMU is started with
memory hotplug enabled but without '-numa' options on CLI.
(PS: auto-create numa node only for new machine types so not to break migration).

Which would provide SRAT table to guests without explicit -numa options on CLI
and would allow:
 * Windows: to enable memory hotplug
 * Linux: switch to SWIOTLB DMA ops, to bounce DMA transfers to 32bit allocated
   buffers that legacy drivers/hw can handle.

[Rewritten by Igor]

Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Suggested-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Alistair Francis <alistair23@gmail.com>
Cc: Takao Indoh <indou.takao@jp.fujitsu.com>
Cc: Izumi Taku <izumi.taku@jp.fujitsu.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>