** Description changed:
+ ## Qemu SRU ##
+
+ [Impact]
+
+ * CPU definitions are added to qemu as these CPUs are known.
+ And due to that over time are missing in former releases.
+
+ * To really benefit from the new features of these chips
+ they have to be known, therefore new type additions done by
+ upstream should be backported if they generally apply and do
+ not depend on SRU-critical changes.
+
+ * This backports two upstream fixes that just add definitions (no
+ control flow changes)
+
+ [Test Case]
+
+ * Probe qemu for the known CPU types (works on all HW)
+ $ qemu-system-x86_64 -cpu ? | grep EPYC
+ Focal without fix:
+ x86 EPYC (alias configured by machine type)
+ x86 EPYC-IBPB (alias of EPYC-v2)
+ x86 EPYC-v1 AMD EPYC Processor
+ x86 EPYC-v2 AMD EPYC Processor (with IBPB)
+ Focal with fix also adds:
+ x86 EPYC-Rome (alias configured by machine type)
+ x86 EPYC-Rome-v1 AMD EPYC-Rome Processor
+ x86 EPYC-v3 AMD EPYC Processor
+
+ * Given such HW is available start a KVM guest using those new types
+ Since we don't have libvirt support (yet) do so directly in qemu
+ commandline like (bootloader is enough)
+ $ qemu-system-x86_64 -cpu EPYC-Rome -machine pc-q35-focal,accel=kvm
-nographic
+ $ qemu-system-x86_64 -cpu EPYC-v3 -machine pc-q35-focal,accel=kvm
-nographic
+
+ [Regression Potential]
+
+ * This adds new CPU types to the list of known CPUs defining their name
+ and features. Generally the changes are contained to those new types
+ and only active when selected - and usually only selectable on such new
+ machines. Therefore not a lot should change for other users.
+ One thing thou, if a user selected an unversioned type (which in this
+ case only can be "EPYC") by default it will pick the latest subversion
+ that applies. In this case the behavior will change and pick EPYC-v3
+ after the fix. But this is the whole purpose of versioned (stay as is)
+ and unversioned (move with updates) CPU types - so that should be ok.
+ The EPYC-Rome type didn't exist in Focal before, so it can't "change"
+ for users.
+
+
+ [Other Info]
+
+ * Depends on the new kernel 5.4.0-49 or later (Currently in
+ focal-proposed)
+
+ ---
+
Qemu in focal has already support for most (except amd-stibp) flags of
this model.
Please backport the following patches:
https://github.com/qemu/qemu/commit/a16e8dbc043720abcb37fc7dca313e720b4e0f0c
https://github.com/qemu/qemu/commit/143c30d4d346831a09e59e9af45afdca0331e819
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https://bugs.launchpad.net/bugs/1887490
Title:
Add/Backport EPYC-v3 and EPYC-Rome CPU model
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