[Qemu-devel] [Query] Does Linux & Qemu support KVM for ARM32 guest on ARM64 host

[RAVINDRA KUMAR SANDE]

What I did  : 
1) Just for investigation, I took a ARMv8 ( OdroidC2 ) board
2)  I compiled Linux 3.14 with KVM support for this ARMv8 ( OdroidC2 ) board, with modification replacing meson_timer by arm timer in its dts file. 
Why Linux 3.14 : I took Linux 3.14 because display drivers for this board are officially for this version; and I am interested in seeing some Linux guest booting with display on.
3)  I see from boot log of  that KVM is initialized successfully, and I can see /dev/kvm node.
4) I built latest Qemu with --enable-kvm on this board natively.

What I find :
1) running "qemu-system-arm  -enable-kvm   -machine vexpress-a9 ...." gives error :  no accelerator found
2) running "qemu-system-aarch64 -enable-kvm  -machine vexpress-a9 ...." gives error : kmv_init_vcpu (IOCtl on /dev/kvm) failed, guest not supported
( I experimented some modifications as well to overcome above error, such as replacing value assigned to cpu->kvm_target etc, but IOCtl call is failing)

Query:
1) Does Arm64 Linux not enable KVM support for Arm32 guest ? 
2) Can qemu-system-arm not use the KVM feature on Arm64 host ? 
3) Can qemu-system-aarch64 not use KVM feature for Arm32 guest ?

Thanks,
Ravindra Sande
PS : Please also point out the possibility ( already done, not done but possible or impossible ) in answer of each of above queries.