We believe all of the in-tree uses of kernel FPU now support using FPU_KERN_NOCTX or allocated contexts.
In cases where FPU support is used multiple times across discrete function calls (none of which rely on the FPU state from the previous one), it seems wasteful to potentially save/restore that state across these calls when there are context switches. Instead, for cases like these with short enough run times, we can rely on FPU_KERN_NOCTX. If the context must be carried across multiple calls or the run time is too long for a critical section, we can use an allocated context.