[Qemu-devel] Cannot launch QEMU with -accel whpx

[Wang Wenchao]

Hi, Justin,

We are interested in WHPX but haven't got it to work. We were able to 
build QEMU with WHPX support. We used MSYS2 build environment plus two 
libraries (WinHv*.lib) from the latest Windows 10 SDK Insider Preview to 
build QEMU and added '--enable-whpx' parameter in config. But when we 
ran it on Windows with Hyper-V on, QEMU failed to be launched.

The command to launch QEMU is as below,

> qemu-system-x86_64.exe -accel whpx

The following errors were output from the command line,

qemu-system-x86_64.exe: WHPX: No accelerator found, hr=00000000
qemu-system-x86_64.exe: failed to initialize WHPX: No space left on device

We analyzed the issue and found when invoking the Windows Hypervisor 
Platform API WHvGetCapability(), it returned whpx_cap.HypervisorPresent 
with FALSE and then WHPX failed to initialize. Do you have any 
suggestion on that? Thanks.

We build and run QEMU on the same machine. Below are its specs,

Windows OS: Windows 10 Insider Preview
Windows edition: Professional
Windows version: 1803 (OS build 17133.1)
SDK version: 10.0.17125.0

Processor: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz 1.99GHz
RAM: 8.00 GB
System Type: 64-bit Operating System, x64-based processor


Best Regards,
Wenchao