Messages in this thread | | | Date | Thu, 01 Mar 2007 19:08:25 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH 4/9] Vmi fix highpte |
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Zachary Amsden wrote: > Provide a PT map hook for HIGHPTE kernels to designate where they are mapping > page tables. This information is required so the physical address of PTE > updates can be determined; otherwise, the mm layer would have to carry the > physical address all the way to each PTE modification callsite, which is > even more hideous that the macros required to provide the proper hooks. > > So lets not mess up arch neutral code to achieve this, but keep the horror > in an #ifdef HIGHPTE in include/asm-i386/pgtable.h. I had to use macros > here because some types are not yet defined in all the include paths for > this header. > > This patch is absolutely required for HIGHPTE kernels to operate properly > with VMI. >
Hm, I don't think this interface will work for Xen. In Xen, whenever a pagetable page gets mapped, it must be mapped RO. map_pt_hook gets called after the mapping has already been created, so its too late for Xen.
I was planning on adding kmap_atomic_pte() for use in pte_offset_map*(), which would be wired through to paravirt_ops to allow Xen to make this a RO mapping. Would this be sufficient for you to do your vmi thing?
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