Re: [PATCH v4] KVM: x86: Fix KVM_GET_CPUID2 ioctl to return cpuid entries count

[Paolo Bonzini]

On 04/05/21 10:15, Denis V. Lunev wrote:
> As far as I understand only some testing within kernel now.
> Though we have plans to expose it for QAPI as the series
> in QEMU
>    [PATCH 1/2] qapi: fix error handling for x-vz-query-cpu-model-cpuid
>    [PATCH 2/2] qapi: blacklisted x-vz-query-cpu-model-cpuid in tests
> is not coming in a good way.
> The idea was to avoid manual code rework in QEMU and
> expose collected model at least for debug.

KVM_GET_CPUID2 as a VM ioctl cannot expose the whole truth about CPUID 
either, since it doesn't handle the TSX_CTRL_CPUID_CLEAR bit.  Given 
that QEMU doesn't need KVM_GET_CPUID2; it only needs to save whatever it 
passed to KVM_SET_CPUID2.

Paolo