Add CPU arch filter scheduler support

In a mixed environment of running different CPU architecutres,
one would not want to run an ARM instance on a X86_64 host and
vice versa.

This scheduler filter option will prevent instances running
on a host that it is not intended for.

The libvirt driver queries the guest capabilities of the
host and stores the guest arches in the permitted_instances_types
list in the cpu_info dict of the host.

The Xen equivalent will be done later in another commit.

The arch filter will compare the instance arch against
the permitted_instances_types of a host
and filter out invalid hosts.

Also adds ARM as a valid arch to the filter.

The ArchFilter is not turned on by default.

Change-Id: I17bd103f00c25d6006a421252c9c8dcfd2d2c49b
Signed-off-by: Chuck Short <chuck.short@canonical.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/nova/utils.py b/nova/utils.py
index ddc998524..8bd71359f 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -1321,6 +1321,15 @@ def strcmp_const_time(s1, s2):
     return result == 0
 
 
+def sys_platform_translate(arch):
+    """Translate cpu architecture into supported platforms."""
+    if (arch[0] == 'i' and arch[1].isdigit() and arch[2:4] == '86'):
+        arch = 'i686'
+    elif arch.startswith('arm'):
+        arch = 'arm'
+    return arch
+
+
 class UndoManager(object):
     """Provides a mechanism to facilitate rolling back a series of actions
     when an exception is raised.