The new tlbi= option has been submitted in time for Linux 7.2 stable and also marked for back-porting to stable Linux kernel versions. This option controls the TLB invalidation method and tlbi=ipi is the only option currently honored. Booting the kernel with tlbi=ipi will switch back to IPI-based Transparent Lookaside Buffer (TLB) flushing.
Due to some recently discovered INVLPGB / TLBSYNC issues on AMD CPUs with INVLPGB used for broadcast TLB flushing on recent kernel versions, this option is added to allow developers/administrators to switch back to the old IPI-based TLB flushing in order to rule it out as a potential cause of user-space crashes.
Thus for now this is just a debug option if wanting to rule out any INVLPGB/TLBSYNC issues on your Linux system. In the future it's mentioned it may be extended to support tlbi=broadcast should the current default behavior change.
The patch is pending via the x86/urgent pull request and should be mainlined to the Linux kernel shortly.