>>> On 22.09.16 at 12:35, <tamas.leng...@zentific.com> wrote: > On Sep 22, 2016 02:56, "Jan Beulich" <jbeul...@suse.com> wrote: >> >> >>> On 21.09.16 at 17:30, <tamas.leng...@zentific.com> wrote: >> > What I'm saying is that the guest OS should be in charge of managing >> > its own TLB when VPID is in use. Whether it does flush the TLB or not >> > is not of our concern. If it's a sane OS it will likely flush when it >> > needs to, but we should not be jumping in and doing it as we do right >> > now. We are actually breaking the architectural behavior by forcing a >> > flush, MOV-TO-CR3 doesn't by itself flush the TLB on real hardware. >> >> I continue to not understand where you take this from. Writes to >> CR3 have always been doing TLB flushes - full ones prior to the >> introduction of global pages, and flushes of only non-global entries >> nowadays. In fact prior to the introduction of INVLPG and CR4 >> there was no other way to flush TLBs. > > Yes, I meant it doesn't completely flush the TLB as we do right now when > invalidating the whole VPID.
But then what architectural behavior do you see broken? Flushing more than is required is always permitted. (And again - I'm all for improvements here, we just need to be careful to not remove flushing that is architecturally required.) Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
