OK, I will write a patch as what Paolo says. Anything else need to be taken into consideration, Paolo? Arthur Chunqi Li Department of Computer Science School of EECS Peking University Beijing, China >From my iPhone 在 2013-7-3，17:14，Gleb Natapov <gleb@xxxxxxxxxx> 写道： > On Wed, Jul 03, 2013 at 04:24:33PM +0800, Arthur Chunqi Li wrote: >> Hi Gleb and Paolo, >> When I write test cases for nested virt and found that reading/writing >> IA32_FEATURE_CONTROL will be simply ignored or return 0 (in >> arch/x86/kvm/vmx.c) in VM. Checking this MSR will be done by some >> hypervisors (e.g. NOVA) and may cause error then, so it is necessary >> to behave right when read/write it in VM. > NOVA cannot write to it and expect anything but #GP since BIOSes usually > lock the MSR. So I agree with Paolo about returning 5 on read and #GP on > write. Later we can implement locking functionality and make BIOS > enable/disable nested vmx. > >> Are there any difficulties to handle this MSR? I have two solutions. >> The first one is return the value of physical CPU's and always return >> true when write. This is simple but may behave as if it is a VM >> because write to it after VMXON will not return GP exception. This >> solution can solve most basic problems since this MSR is not commonly >> used. Another solution is adding a field in VCPU to handle this MSR. >> This is a complex but better method. >> >> I think I can complete this if needed. >> >> Thanks, >> Arthur >> >> -- >> Arthur Chunqi Li >> Department of Computer Science >> School of EECS >> Peking University >> Beijing, China > > -- > Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
