Re: [Qemu-devel] Problem building QEMU with whpx support

[Justin Terry (VM)]

Hey Umang,

Sorry I missed this. There is no official documentation for building QEMU on 
WHP as there is really no difference to cross compiling QEMU in general. 
However, yes you can cross compile this on 18.04 (and other distros). After 
installing the correct packages (mingw-w64) you will end up with a path on your 
Linux machine “/usr/x86_64-w64-mingw32/include/” folder. If you copy 
WinHvEmulation.h, WinHvPlatformDefs.h, WinHvPlatform.h from any “C:\Program 
Files (x86)\Windows Kits\10\Include\<version>\um\WinHv*.h” installed insider 
SDK you can then run “./configure --target-list=x86_64-softmmu 
--cross-prefix=x86_64_w64-mingw32- --enable-whpx” … (Etc). This will output a 
qemu binary that can be run on the Windows host.

Note, my personal way of doing this (not a requirement) is to use WSL on the 
same machine I am testing with. So I have enabled the Windows Subsystem for 
Linux, installed a distro of my choosing, copied the headers from the installed 
SDK, and run ./configure. I then have the output of make on a shared drive, so 
I can open cmd.exe launch the qemu exe with whatever options and test out my 
changes. Hope this helps!

-Justin

From: Umang Kakaiya <address@hidden>
Sent: Thursday, June 21, 2018 2:44 PM
To: address@hidden; Justin Terry (VM) <address@hidden>
Subject: Problem building QEMU with whpx support

Hi Justin,

We are trying to use QEMU on Windows Hyper-V environment with whpx enabled for 
better performance. We were unable to build QEMU with WHPX support. We used 
Ubuntu 18.04 server VM with two libraries (WinHv*.lib) from the latest Windows 
10 SDK to build QEMU and added '--enable-whpx' parameter in config. But 
building is failing giving the following message:
The command to launch QEMU is as below,

$ ./configure --enable-whpx --enable-debug

The following error was output from the command line,
Error: User requested feature WinHvPlatform
       configure was not able to find it.
       WinHvEmulation is not installed.

We analyzed the issue and found that configure is unable to locate the 
WinHvPlatform.h file.
As for providing WinHV*.lib files we tried following steps:
1. We set LD_LIB_PATH to point to the WinHV*.lib files.
2. We used --path_win_sdk option in configure to add the path to Windows 
insider SDK.
3. We moved to Windows Environment and tried building QEMU with MSYS2 build 
options according to steps mentioned in QEMU blog 
(Link<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwiki.qemu.org%2Findex.php%2FHosts%2FW32%23Native_builds_with_MSYS2&data=02%7C01%7Cjuterry%40microsoft.com%7C7cb5af61e68f4adb723c08d5d7c0252c%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C1%7C636652142620044047&sdata=VhqbjvzvQbjIn8WYmAqOGaU2QM7CnhCVpE4VrV4sepI%3D&reserved=0>)
But it didn't work because base qemu build itself fails. We then      tried 
MingW64 to build QEMU but got the same error above with --enable-whpx.


We tried to find any documentation to provide exact steps in building QEMU with 
whpx support but didn't make any progress. So there are three questions:

1. Can we build QEMU with whpx packages on Ubuntu 18.04 or do we need to use 
QEMU native build on Windows machine using MSYS2.
2. Where to keep the WinHV*.lib files in QEMU source directories so that 
configure can locate the files for build.
3. Can you provide any links or reference to documentation on building QEMU 
with whpx support with all dependency packages required.

Below is the configuration of the Hyper-V machine used for this experiment,

Windows OS: Windows Server Datacenter 2016
Windows edition: Server
Windows version: 1803 (OS build 17645.1042)
SDK version: 10.0.17686.0


Best Regards,
Umang