From: Eduardo Habkost <ehabkost@redhat.com>
To: qemu-devel@nongnu.org
Cc: libvir-list@redhat.com, Igor Mammedov <imammedo@redhat.com>,
Jiri Denemark <jdenemar@redhat.com>,
"Daniel P. Berrange" <berrange@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: [Qemu-devel] [PATCH 5/6] docs: Deprecate CPU model runnability guarantees
Date: Tue, 25 Jun 2019 02:00:07 -0300 [thread overview]
Message-ID: <20190625050008.12789-6-ehabkost@redhat.com> (raw)
In-Reply-To: <20190625050008.12789-1-ehabkost@redhat.com>
Document that CPU model runnability guarantees won't apply to
unversioned CPU models anymore.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Cc: libvir-list@redhat.com
---
qemu-deprecated.texi | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
index df04f2840b..5fafb62a6d 100644
--- a/qemu-deprecated.texi
+++ b/qemu-deprecated.texi
@@ -243,3 +243,22 @@ Note that if you are exposing the export via /dev/nbd0, it is easier
to just export the entire image and then mount only /dev/nbd0p1 than
it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
subset of the image.
+
+@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.
--
2.18.0.rc1.1.g3f1ff2140
next prev parent reply other threads:[~2019-06-25 5:08 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-25 5:00 [Qemu-devel] [PATCH 0/6] x86 CPU model versioning Eduardo Habkost
2019-06-25 5:00 ` [Qemu-devel] [PATCH 1/6] i386: Add x-force-features option for testing Eduardo Habkost
2019-06-25 5:00 ` [Qemu-devel] [PATCH 2/6] i386: Remove unused host_cpudef variable Eduardo Habkost
2019-06-25 9:04 ` Dr. David Alan Gilbert
2019-06-25 5:00 ` [Qemu-devel] [PATCH 3/6] qmp: Add "alias-of" field to query-cpu-definitions Eduardo Habkost
2019-06-25 16:15 ` Daniel P. Berrangé
2019-06-25 18:00 ` Eduardo Habkost
2019-06-25 5:00 ` [Qemu-devel] [PATCH 4/6] i386: Infrastructure for versioned CPU models Eduardo Habkost
2019-06-25 9:32 ` Dr. David Alan Gilbert
2019-06-25 13:40 ` Eduardo Habkost
2019-06-25 14:32 ` Dr. David Alan Gilbert
2019-06-25 14:53 ` Eduardo Habkost
2019-06-25 14:56 ` Dr. David Alan Gilbert
2019-06-25 16:05 ` Eduardo Habkost
2019-06-25 16:26 ` Daniel P. Berrangé
2019-06-25 17:59 ` Eduardo Habkost
2019-06-25 18:08 ` Daniel P. Berrangé
2019-06-25 18:11 ` Eduardo Habkost
2019-06-25 5:00 ` Eduardo Habkost [this message]
2019-06-25 5:00 ` [Qemu-devel] [PATCH 6/6] i386: Add Cascadelake-Server-4.1.1 CPU model Eduardo Habkost
2019-06-25 5:35 ` Tao Xu
2019-06-25 13:11 ` Eduardo Habkost
2019-06-25 5:15 ` [Qemu-devel] [PATCH 0/6] x86 CPU model versioning no-reply
2019-06-25 16:13 ` Daniel P. Berrangé
2019-06-25 18:11 ` Eduardo Habkost
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