Re: [Xen-devel] [PATCH 00/10] x86/hvm: pkeys, add memory protection-key support

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 16.11.15 at 18:45, <andrew.cooper3@xxxxxxxxxx> wrote:
> Furthermore, it is unclear (given the unwritten ABI) whether it is even
> safe to move _PAGE_GNTTAB out of the way, as this is visible to a PV guest.

It seems pretty clear to me that this would be unsafe: It being
part of L1_DISALLOW_MASK, if it moved and a guest used the
bit for its own purposes, the guest would break. I guess we'll
need an ELF note by which the guest can advertise which of the
available bits it doesn't care about itself.

Jan


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