mm/hmm/test: add selftest driver for HMM

This driver is for testing device private memory migration and devices
which use hmm_range_fault() to access system memory via device page tables.

Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ralph Campbell <[email protected]>
Signed-off-by: Jérôme Glisse <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Yongjun <[email protected]>
Link: https://lore.kernel.org/r/20200511183704.GA225608@mwanda
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
4 files changed