Zachary Amsden wrote:
> No, I don't mean the Linux PDA - how do you access the Xen PDA? Or
> have they conjoined somehow?
You could put it that way I guess. There's a generic Linux PDA; a
paravirt patch adds a union for pv use, and a Xen patch adds a
Xen-specific element to that union. That's how it has been from the
start, so there wasn't really anything to conjoin (there was never a Xen
PDA per se).
> So your invalidate "IPI" is actually a hypercall, and you can use the
> existing flush_tlb interface for the most part. You just need a
> paravirt-op then for the IPI itself, which takes a CPU mask - and this
> seems to match nicely onto your hypercall.
Yep. There are calls for flushing the whole tlb, and for just a page;
both take CPU masks.
> I think you might want to optimize this a bit more, however, since in
> some cases you will issue implicit shootdown IPIs during a pte update
> hypercall.
Not that I've seen, at least none that doesn't also exist in baseline.
> This seems much cleaner than designing the shootdown semantic directly
> into such PTE updates, which is I believe what some of the older Xen
> patches did, although I could have misread them.
I was starting on SMP with the idea that it would be relatively isolated
and simple, but it seems I should probably do the MMU stuff first to see
what impact it has on SMP.
J
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