Hi I'm working on an extension to QEMU (target i386). This involves adding new MSR's. I've got it working in non-KVM mode by adding these MSR's to the state and adding extra cases to helper_wrmsr(), helper_rdmsr(). The guest can now read/write these MSR's as expected. However, it fails when running in KVM-mode. Specifically, writing the MSR's causes GPF. Note that these MSR's are not natively supported by the host CPU. I don't know enough about Intel's VMX to tell if it is even reasonable to expect that this could work for a non-natively supported MSR. As far as I can read in the VMX documentation, the hypervisor can setup a bitmap of which MSR's should cause trap's to the hypervisor and which shouldn't. I guess it would be the KVM kernel module that does this based on input it receives from QEMU. But I haven't been able to find the part of QEMU that negotiates this. I guess the solution for me is to set the necessary bits to that access to the new MSR's causes traps. Next, I need to add/modify the trap handler so that it can handle the MSR's.
I would much appreciate any help. Thanks!
