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graphic: 0.871
debug: 0.851
device: 0.818
architecture: 0.775
virtual: 0.747
vnc: 0.742
semantic: 0.726
hypervisor: 0.713
performance: 0.683
user-level: 0.681
ppc: 0.677
boot: 0.676
kernel: 0.655
register: 0.631
mistranslation: 0.625
permissions: 0.583
VMM: 0.570
socket: 0.557
assembly: 0.524
PID: 0.495
network: 0.494
KVM: 0.471
risc-v: 0.435
files: 0.434
arm: 0.421
x86: 0.396
i386: 0.335
peripherals: 0.318
TCG: 0.277
CPU Hotplug (Host Model) Causes the Windows VM to BSOD
Description of problem:
The QEMU runs on a host with the Intel(R) Xeon(R) CPU E3-1230 v6 CPU which supports Software Guard Extension (SGX). I start a VM with Windows Server 2019 inside and with `-cpu host,...`. When I attempts to hotplug additional CPU (when the VM is running), the OS issues a bug check 0x3e (`MULTIPROCESSOR_CONFIGURATION_NOT_SUPPORTED`). The problem is that the newly hotplugged CPU is not evaluated as "equivalent enough" compared to the already present CPUs. I did some more digging and reverse engineering and it looks like the CPU being hotplugged has SGX turned off. This seems to be fixed when the VM reboots.
I tried to disable SGX through `-cpu host,-sgx` which helps (the VM successfully accepts the hotplugged CPU), however, `+sgx` does not help (seems to have no effect on the CPU being hotplugged).
My goal is to be able to hotplug CPUs even when the host CPU supports SGX.
I tested with QEMU 8.0.0, 9.1.0, 9.1.1 and 9.1.50 (current master) but with no luck.
Steps to reproduce:
1. Create a simple Windows VM,
2. start the VM,
3. use `qpm-shell` to hotplug a CPU (https://www.qemu.org/docs/master/system/cpu-hotplug.html).
I can provide you the VM as well but its image (QCOW2) has around 10G in size.
Best regards
Martin Dráb
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