Allocating physical memory without a kernel mapping

[Alexander Eichner]

Hi,

I'm currently trying to finish the R0 memory implementation[1] of FreeBSD for VirtualBox. One of the missing methods allocates physical non contiguous pages which don't need to have a kernel mapping (rtR0MemObjNativeAllocPhysNC). I'm using vm_phys_alloc_contig to achieve this. The pages are than mapped into the user space VM process using pmap_enter (rtR0MemObjNativeMapUser) and if they are not needed anymore vm_page_free_toq is used to free the pages (rtR0MemObjNativeFree).
Everything works as long as the VM runs but if the VM process terminates and I do something else the host will panic at some point (usually when I try to start a gnome session) with "pmap_enter: missing reference to page table page <va>"[2].
There seems to some problem with the wire count of that page but I can't see what I'm doing wrong at the moment.
Thanks in advance for any help.

Regards,
Alexander Eichner

[1] http://www.virtualbox.org/browser/trunk/src/VBox/Runtime/r0drv/freebsd/memobj-r0drv-freebsd.c?rev=26899
[2]http://fxr.watson.org/fxr/source/amd64/amd64/pmap.c?im=bigexcerpts#L3076

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