Re: [PATCH 00/19] Refresh queued CET virtualization series

[Paolo Bonzini]

On 6/16/22 12:12, Peter Zijlstra wrote:
> Do I understand this right in that a host without X86_KERNEL_IBT cannot
> run a guest with X86_KERNEL_IBT on? That seems unfortunate, since that
> was exactly what I did while developing the X86_KERNEL_IBT patches.
>
> I'm thinking that if the hardware supports it, KVM should expose it,
> irrespective of the host kernel using it.

For IBT in particular, I think all processor state is only loaded and 
stored at vmentry/vmexit (does not need XSAVES), so it should be feasible.

Paolo