On Wed, 2024-01-03 at 00:25 +0200, Maxim Levitsky wrote: > I still think that we should consider adding XFEATURE_MASK_CET_KERNEL > to > XFEATURE_MASK_INDEPENDENT or at least have a good conversation on why > this doesn't make sense, > but I also don't intend to fight over this, as long as the code > works. Hi, Using XFEATURE_MASK_INDEPENDENT would be pretty close to what we initially discussed when this series resumed: https://lore.kernel.org/lkml/20230803042732.88515-10-weijiang.yang@xxxxxxxxx/ Except that it used manual MSR operations instead of xsaves. But the gist is the same I think - the state is managed manually by KVM. A XFEATURE_MASK_INDEPENDENT solution seems reasonable to me. I kind of liked the that the MSR version didn't complicate the overly complex FPU code. But there was an idea to give XFEATURE_MASK_KERNEL_DYNAMIC a try, to see if it turned out easy. I think it turned out "ok" complexity wise. So it doesn't make it clear win one way or the other for me. I guess it might be slightly more efficient as in this patch because it gets to use the lazy FPU stuff. It won't need to save/restore if the exit is handled within KVM, or the kernel switches to a kernel thread and back. I think that tilts it in favor of XFEATURE_MASK_KERNEL_DYNAMIC. Rick
