Re: [Xen-devel] Question about VPID during MOV-TO-CR3

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.09.16 at 17:30, <tamas.lengyel@xxxxxxxxxxxx> 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.

Jan


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