376a240f03
Tearing down a previously shared memory region results in the borrower losing access to the underlying pages and returning them to the "owned" state in the owner. Implement a do_unshare() helper, along the same lines as do_share(), to provide this functionality for the host-to-hyp case. Reviewed-by: Andrew Walbran <qwandor@google.com> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Quentin Perret <qperret@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20211215161232.1480836-13-qperret@google.com