[CentOS-virt] XSAs 170 and 154, repository layouts, and centos-release-xen 8-1

[George Dunlap]

I have the following packages going through the CBS:
* A CentOS 7 xen-4.6.1-2, with XSAs 170 and 154
* A CentOS 6 xen-4.6.1-2, with XSAs 170 and 154
* A CentOS 6 xen-4.4.3-11, with XSAs 170

All these should show up in mirrors hopefully sometime later today.
As usual, please report any problems here.

Xen 4.4 only has XSA 170 because at the time the embargo was lifted, I
didn't have a suitable backport of XSA-154.  It's only applicable when
PCI-passthrough is in effect, so it's not that critical.

Additionally, we've moved to the new repository layout.  Repositories
will now be tagged with the release; so C6 will have xen-44 and
xen-46, and C7 will have xen-46.  For now, the existing xen/
repository will be a symlink -- to xen-44 for C6 and to xen-46 for C7.

There will be new centos-release-xen packages coming down the line.
As described elsewhere:

* centos-release-xen-44 will always point to the xen-44 repository
* centos-release-xen-46 will always point to the xen-46 repository
* centos-release-xen will (normally) point to whatever the most recent
release is.

For the time being, the C6 version of centos-release-xen will remain
pointing to xen-44.

These packages can be installed at the same time; yum will choose the
most recent release of all available.

= What you need to do (C6 users only) =

* If you want to stay on xen-44:

yum install centos-release-xen-44
yum remove centos-release-xen

* If you want to update to xen-46 and stay there until you choose to update:

yum install centos-release-xen-46
yum remove centos-release-xen

* If you want to update to xen-46, and also get further updates automatically:

yum install centos-release-xen-46

= What you need to do (C7 users) =

Much less urgent, since we don't plan to upgrade until 4.8, but:

* If you want to stay on 46 until you choose to update:

yum install centos-release-xen-46
yum remove centos-release-xen

* If you want to get further updates automatically:

Do nothing, you're already set.