>>> On 20.09.16 at 19:29, <tamas.leng...@zentific.com> wrote: > I'm trying to figure out the design decision regarding the handling of > guest MOV-TO-CR3 operations and TLB flushes. AFAICT since support for > VPID has been added to Xen, every guest MOV-TO-CR3 flushes the TLB > (vmx_cr_access -> hvm_mov_to_cr -> hvm_set_cr3 -> paging_update_cr3 -> > hap_update_cr3 -> vmx_update_guest_cr -> hvm_asid_flush_vcpu). From a > TLB utilization point-of-view this seems to be rather wasteful. > Furthermore, it even breaks the guests' ability to take advantage of > PCID, as the TLB just guts flushed when a new process is scheduled. > Does anyone have an insight into what was the rationale behind this?
Since you don't quote the specific commit(s), I would guess that this was mainly an attempt by the author(s) to keep things simple for themselves, i.e. not having to properly think through under which conditions less than a full TLB flush would suffice. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
