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SubjectRe: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor
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Radim Krčmář <rkrcmar@redhat.com> writes:
...
>> > and no other mentions of a VM exit, so I think that the VM exit happens
>> > only under these conditions:
>> >
>> > — The EPT memory type (bits 2:0) must be a value supported by the
>> > processor as indicated in the IA32_VMX_EPT_VPID_CAP MSR (see
>> > Appendix A.10).
>> > — Bits 5:3 (1 less than the EPT page-walk length) must be 3, indicating
>> > an EPT page-walk length of 4; see Section 28.2.2.
>> > — Bit 6 (enable bit for accessed and dirty flags for EPT) must be 0 if
>> > bit 21 of the IA32_VMX_EPT_VPID_CAP MSR (see Appendix A.10) is read
>> > as 0, indicating that the processor does not support accessed and
>> > dirty flags for EPT.
>> > — Reserved bits 11:7 and 63:N (where N is the processor’s
>> > physical-address width) must all be 0.
>> >
>> > And it looks like we need parts of nested_ept_init_mmu_context() to
>> > properly handle VMX_EPT_AD_ENABLE_BIT.
>>
>> I completely ignored AD and the #VE sections. I will add a TODO item
>> in the comment section.
>
> AFAIK, we don't support #VE, but AD would be nice to handle from the
> beginning. (I think that caling nested_ept_init_mmu_context() as-is
> isn't that bad.)

I went back to the spec to take a look at the AD handling. It doesn't look
like anything needs to be done since nested_ept_init_mmu_context() is already
being called with the correct eptp in prepare_vmcs02 ? Anything else that
needs to be done for AD handling in vmfunc context ?

Thanks,
Bandan

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