Re: [PATCH v11 7/7] KVM: x86: virtualize cpuid faulting
From: Kyle Huey
Date: Wed Nov 16 2016 - 11:40:16 EST
On Fri, Nov 11, 2016 at 12:54 PM, Nadav Amit <nadav.amit@xxxxxxxxx> wrote:
>> On Nov 10, 2016, at 3:40 PM, Kyle Huey <me@xxxxxxxxxxxx> wrote:
>> Hardware support for faulting on the cpuid instruction is not required to
>> emulate it, because cpuid triggers a VM exit anyways. KVM handles the relevant
>> MSRs (MSR_PLATFORM_INFO and MSR_MISC_FEATURES_ENABLE) and upon a
>> cpuid-induced VM exit checks the cpuid faulting state and the CPL.
>> kvm_require_cpl is even kind enough to inject the GP fault for us.
> I think that for consistency you should also revise em_cpuid() of KVM
> instruction emulator. Otherwise it may be a potential security
> hazard (as far fetched as it currently seems).
Hmm, ok. Do you know how I can test this code path?