[Xiaowei Yang]
> Espen,
> The patches look good to me with some comments:
> - For the occasions when P2M is changed, the hooks of
> iommu_{un}map_page() can be added cleaner. Only the hooks inside
> guest_physmap_add/remove_page() are necessary. The hooks in
> populate_physmap() and memory_exchange() can be omitted by some
> small code rearrangement like removing if(paging_mode_translate(d))
> before calling guest_physmap_add_page().
Yes. I considered this as an option as well, but ended up with the
current approach. Your suggestion is probably cleaner, so I'll switch
over to doing that.
> - gnttab_map/unmap_grant_ref() need to be hooked also. There are no
> P2M changes at that time while the guest PT is updated directly. The
> mapped pages can also be used for DMA by backend drivers.
Thanks. Overlooked that one. Only caught the gnttab_transfer().
> - dom0 can be treated as the same as other PV domains with regard to
> VTd PT updating. Unfortunately, it need some special care. All of
> devices are assigned to it by default and usually it ones the most
> of devices. iommu_{un}map_page() could be called very frequently by
> it while it serves other domains IO requests. It will bring
> performance penalty and CPU overhead.
dom0 should not need to do any VT-d page table updating once it has
been set up, so marking it as need_iommu() should be unnecessary.
Also, if passthrough mode is supported in VT-d then dom0 does not need
to have VT-d page tables at all. I think setting it's VT-d tables up
to have complete access at startup and leave it that way is perfectly
fine.
Thanks for feedback. Will repost once I've incorporated all the
comments.
 eSk
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