From aa5b969287125d1924d74648b378d4abba544465 Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Thu, 27 Jun 2019 21:28:43 -0300 Subject: [PATCH] docs: Deprecate CPU model runnability guarantees MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Document that CPU model runnability guarantees won't apply to unversioned CPU models anymore. Signed-off-by: Eduardo Habkost Message-Id: <20190628002844.24894-9-ehabkost@redhat.com> Reviewed-by: Daniel P. Berrangé Signed-off-by: Eduardo Habkost --- qemu-deprecated.texi | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi index e6891c3a93..c90b08d553 100644 --- a/qemu-deprecated.texi +++ b/qemu-deprecated.texi @@ -292,3 +292,22 @@ subset of the image. In the future, QEMU will require Python 3 to be available at build time. Support for Python 2 in scripts shipped with QEMU is deprecated. + +@section Backwards compatibility + +@subsection Runnability guarantee of CPU models (since 4.1.0) + +Previous versions of QEMU never changed existing CPU models in +ways that introduced additional host software or hardware +requirements to the VM. This allowed management software to +safely change the machine type of an existing VM without +introducing new requirements ("runnability guarantee"). This +prevented CPU models from being updated to include CPU +vulnerability mitigations, leaving guests vulnerable in the +default configuration. + +The CPU model runnability guarantee won't apply anymore to +existing CPU models. Management software that needs runnability +guarantees must resolve the CPU model aliases using te +``alias-of'' field returned by the ``query-cpu-definitions'' QMP +command.