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Konrad Rzeszutek Wilk authored
Revert "xen/x86: Workaround 64-bit hypervisor and 32-bit initial domain." and "xen/x86: Use memblock_reserve for sensitive areas." This reverts commit 806c312e and commit 59b29440 . And also documents setup.c and why we want to do it that way, which is that we tried to make the the memblock_reserve more selective so that it would be clear what region is reserved. Sadly we ran in the problem wherein on a 64-bit hypervisor with a 32-bit initial domain, the pt_base has the cr3 value which is not neccessarily where the pagetable starts! As Jan put it: " Actually, the adjustment turns out to be correct: The page tables for a 32-on-64 dom0 get allocated in the order "first L1", "first L2", "first L3", so the offset to the page table base is indeed 2. When reading xen/include/public/xen.h's comment very strictly, this is not a violation (since there nothing is said that the first thing in the page table space is pointed to by pt_base; I admit that this seems to be implied though, namely do I think that it is implied that the page table space is the range [pt_base, pt_base + nt_pt_frames), whereas that range here indeed is [pt_base - 2, pt_base - 2 + nt_pt_frames), which - without a priori knowledge - the kernel would have difficulty to figure out)." - so lets just fall back to the easy way and reserve the whole region. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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