[Bug 2077321] Re: Please backport the more restrictive XSAVES deactivation for Zen1/2 arch

This bug is awaiting verification that the linux-xilinx/6.8.0-1009.10
kernel in -proposed solves the problem. Please test the kernel and
update this bug with the results. If the problem is solved, change the
tag 'verification-needed-noble-linux-xilinx' to 'verification-done-
noble-linux-xilinx'. If the problem still exists, change the tag
'verification-needed-noble-linux-xilinx' to 'verification-failed-noble-
linux-xilinx'.


If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.


See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: kernel-spammed-noble-linux-xilinx-v2 verification-needed-noble-linux-xilinx

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https://bugs.launchpad.net/bugs/2077321

Title:
Please backport the more restrictive XSAVES deactivation for Zen1/2
arch

Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Jammy:
Fix Committed
Status in linux source package in Noble:
Fix Committed
Status in linux source package in Oracular:
Confirmed

Bug description:
On recent kernels, commit https://git.launchpad.net/~ubuntu-
kernel/ubuntu/+source/linux/+git/jammy/commit/?id=b0563468eeac88ebc70559d52a0b66efc37e4e9d
deactivate the XSAVES instruction for Zen 1/2 architectures.

This means that for a QEMU vm using cpu=host running on older kernels
where XSAVES is activated, it will not be possible to migrate that VM
to newer kernels which have the XSAVES disabled.

The more recent commit
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=29ba89f1895285f06c333546882e0c5ae9a6df23
only deactivates XSAVES on kernel where the fixed microcode is not
present.

This will prevent the QEMU migration problem to occur on AMD system
where the microcode has been correctly updated.

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