** Description changed:
+ [ Impact ]
+
+ * Windows 11 released a Windows update several months back that broke it on
AMD Processors on KVM when using host-passthrough CPU mode. Users can no longer
run
+ the Windows 11 VMs.
+
+ [ Test Plan ]
+
+ * There are several ways to test this fix, one way is to run Windows 11 VM
+ but it is a little bit complex. We can test this fix by checking if the
+ faulty behavior that causes Windows 11 stop working has been fixed.
+
+ * The faulty behavior is about to always enabling (emulate)
arch-capabilities
+ on AMD CPUs even if AMD CPUs do not have this feature.
+
+ * The right behavior is : when users do not explicitly specify the arch-
+ capabilities feature, it should ONLY be enabled when the CPU has it.
+
+ * Here are the tests steps:
+ - on AMD CPU without arch-capabilities (for example : AMD EPYC Genoa - but
+ you can verify if your CPU has it by using cpuid).
+
+ - First run a VM:
+ $ qemu-system-x86_64 -enable-kvm -cpu host -vga none -monitor stdio -vnc
:999 -qmp unix:/tmp/qmp.sock,server,nowait
+
+ - Second verify that the VM does not have "arch-capabilities" set to
+ true
+
+ $ ( echo '{"execute":"qmp_capabilities"}'; echo
+ '{"execute":"query-cpu-model-
+ expansion","arguments":{"type":"full","model":{"name":"host"}}}'; ) |
+ sudo socat - UNIX-CONNECT:/tmp/qmp.sock | grep arch-capabilities
+
+ [ Where problems could occur ]
+
+ * Since we modify the CPU features on an old Ubuntu releases, this breaks
the
+ migration of existing VMs to newer Ubuntu releases.
+
+ To avoid that we add new Ubuntu machine type and enable the fix only for
this
+ new machine type. We also make this new machine type the default one so
that
+ users can benefit from the fix transparently.
+
+ This ensure the migration to happen correctly. However, we might want to
keep
+ in mind that if there will be any regression caused by this SRU, it would
be likely related to the migration feature.
+
+
+ [ Other Info ]
+
+ None
+
+
+ Original bug report
+ ---------------------
+
Issue has been discovered by HPE :
---------------------------------------------------------
Got some updates on this.
-
+
Firstly, we are using Ubuntu 24.04 LTS Base as 26.04 is not out yet. This
means QEMU version is 8.2.2.
I tried to use Windows 11 25H2 ISO instead and this sort of worked. We got
past install and into the setup wizard. But as soon as Windows Updates were
downloaded and kicked off, the system went back to KMODE EXCEPTION (0x1E)
-
- I believe this only occurs if Secure Boot is enabled (UEFI Non secure with SW
TPM 2.0 seems to work ok last I checked).
+ I believe this only occurs if Secure Boot is enabled (UEFI Non secure
+ with SW TPM 2.0 seems to work ok last I checked).
----------------------------------------------------------
There are several articles on it online but short summary
-
-
https://forum.proxmox.com/threads/amd-bsod-unsupported-processor-since-windows-build-26100-4202-update-kb5060842-its-preview-kb5058499.166828/
-
- Windows 11 released a Windows update several months back that broke it on AMD
Processors on KVM when using host-passthrough CPU mode. The solutions suggested
out there are often to switch cpu model to x86-64-v4. We noticed this only
happens when Secure Boot is used (UEFI non secure is fine). We are trying to
dig farther we have it tracked in JIRA as PCCP-7972 but were curious if you all
hand any insight here or could help us find a solution as this is something
inside kvm/qemu .
-
+
+ https://forum.proxmox.com/threads/amd-bsod-unsupported-processor-since-
+ windows-build-26100-4202-update-kb5060842-its-preview-kb5058499.166828/
+
+ Windows 11 released a Windows update several months back that broke it
+ on AMD Processors on KVM when using host-passthrough CPU mode. The
+ solutions suggested out there are often to switch cpu model to
+ x86-64-v4. We noticed this only happens when Secure Boot is used (UEFI
+ non secure is fine). We are trying to dig farther we have it tracked in
+ JIRA as PCCP-7972 but were curious if you all hand any insight here or
+ could help us find a solution as this is something inside kvm/qemu .
+
Thanks,
David Estes
-
----------------------------------
This specific observation is subject of a QEMU issue Windows 11 24H2
(KB5063060) fails to boot with 'UNSUPPORTED PROCESSOR' on multi-core QEMU
guests with AMD EPYC host (#3001) · Issue · qemu-project/qemu
The root cause and QEMU patch
https://lore.kernel.org/qemu-devel/[email protected]/
The last update in the QEMU issue tracker from a week ago details the release
intercept plans for the fix. Fixed in 10.0.4, though the fixed caused a
regression that was fixed in 10.0.6, and confirms 10.1.x has the fix.
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https://bugs.launchpad.net/bugs/2131822
Title:
Known Windows 11 KVM Issue AMD KMODE Exception
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