Messages in this thread | | | Subject | Re: [RFC PATCH 0/4] KVM: Emulate UMIP (or almost do so) | From | Paolo Bonzini <> | Date | Fri, 10 Mar 2017 16:00:06 +0100 |
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On 10/03/2017 10:31, Yu Zhang wrote: >> We can also add a module parameter to force emulation, so that it will >> be possible to test UMIP emulation on newer processors too. > > Thanks for your reply, Paolo. :-) > > Well, my previous understanding is that there might be a situation on a > machine with UMIP > feature: > 1> when an APP in VM runs instructions such as sgdt addrA, > 2> and the addrA may cause anVM exit(e.g. ept violation), > 3> next, the emulator in hypervisor need to inject a GP fault to the VM. > Is this situation possible?
No, the guest will execute the instruction again after the vmexit.
> But as to the scenario you described, I do not quit understand. > I mean, on a host which do not support UMIP, although hypervisor may > intercept cpuid and > provide an emulated cr4 to guest, how does it guarantee those > instructions in VM will cause a VM exit?
All instructions except SMSW can be trapped using descriptor table vmexits.
Paolo
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