问题
I read from here that vmx capability support on QEMU must be explicitly enabled by providing the +vmx option to the command but the problem is that it does not seem to work. In my system, the VMX feature is still undetected.
Command:
qemu-system-x86_64 -no-kvm -cpu qemu64,+vmx,-svm ...
In my guest OS, when I execute cpuid 1 I get ECX = 0x80802001; bit 5 = 0 meaning that my virtual CPU does not have VMX.
Is this a bug?
Or is there another way to enable the vmx feature in QEMU?
回答1:
The following command works for me:
qemu-system-x86_64 -cpu host -kernel kernel/kernel -serial stdio -enable-kvm
-cpu host makes QEMU report host CPU features inside the VM (so your CPU must support vmx)
-enable-kvm is required by -cpu host
Even though according to this -cpu qemu64,+vmx should work, it doesn't work for me either.
回答2:
No, the vmx flag is not supported in the processor emulation mode of QEMU. In order to use vmx in QEMU, you must use KVM with QEMU (replacing -no-kvm with -enable-kvm); and your host processor must support vmx.
In this document it shows the nested vmx instructions support in the Linux KVM; meaning this feature must be used with -enable-kvm.
In my test the options -enable-kvm -cpu kvm64,+vmx work, as the vmx feature is detected in the guest OS.
来源：https://stackoverflow.com/questions/39154850/how-do-i-emulate-the-vmx-feature-with-qemu