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
