On 2/17/22 05:31, Brian Geffon wrote: > How would you and Greg KH like to proceed with this? I'm happy to help > however I can. If I could wave a magic wand, I'd just apply the whole FPU rewrite to stable. My second choice would be to stop managing PKRU with XSAVE. x86_pkru_load() uses WRPKRU instead of XSAVE and keeps the task's PKRU in task->pkru instead of the XSAVE buffer. Doing that will take some care, including pulling XFEATURE_PKRU out of the feature mask (RFBM) at XRSTOR. I _think_ that can be done in a manageable set of patches which will keep stable close to mainline. I recognize that more bugs might get introduced in the process which are unique to stable. If you give that a shot and realize that it's not feasible to do a subset, then we can fall back to the minimal fix. I'm not asking for a multi-month engineering effort here. Maybe an hour or two to see if it's really as scary as it looks.
