Zachary Amsden wrote: > Nakajima, Jun wrote: > > And actually you don't need the write to CR3 to flush TLB because the > > one to CR4 does it. Or does kvm_flush_tlb_kernel assume that CR3 is updated > > at the same time? > > > > Jun > > It should not be necessary, but I believe this was added as a workaround > to a PII erratum. I can't find the erratum, however, and the history of > using G bits in Linux is complicated (several bugs introduced and many > intermediate versions of this code). Since this is not performance > critical, I think it is probably best to leave the CR3 reload. I don't recommend this for old processors. > > However, being unnecessary on modern processors, I already submitted a > patch to eliminate it on 64-bit (or maybe just told Andi about it, I > can't recall). > > Zach For KVM, it should be okay as well. But we can replace two CR4 accesses with just one hypercall. Jun --- Intel Open Source Technology Center _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
