[v1,0/3] virtio-mem: disallow mapping virtio-mem memory via /dev/mem

Message

David Hildenbrand Aug. 11, 2021, 8:36 p.m. UTC

Let's add the basic infrastructure to exclude some physical memory
regions completely from /dev/mem access, on any architecture and under
any system configuration (independent of CONFIG_STRICT_DEVMEM and
independent of "iomem=").

Use it for virtio-mem, to disallow mapping any virtio-mem memory via
/dev/mem to user space after the virtio-mem driver was loaded: there is
no sane use case to access the device-managed memory region via /dev/mem
once the driver is actively (un)plugging memory within that region and
we want to make sure that nobody will accidentially access unplugged
memory in a sane environment.

Details can be found in patch #1.

Cc: Arnd Bergmann <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: "Michael S. Tsirkin" <[e-mail]>
Cc: Jason Wang <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Hanjun Guo <[e-mail]>
Cc: Andy Shevchenko <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]

David Hildenbrand (3):
  /dev/mem: disallow access to explicitly excluded system RAM regions
  virtio-mem: disallow mapping virtio-mem memory via /dev/mem
  kernel/resource: cleanup and optimize iomem_is_exclusive()

 drivers/char/mem.c          | 22 ++++++-------
 drivers/virtio/virtio_mem.c |  4 ++-
 include/linux/ioport.h      |  1 +
 kernel/resource.c           | 61 ++++++++++++++++++++++++++++++++-----
 lib/Kconfig.debug           |  4 ++-
 5 files changed, 69 insertions(+), 23 deletions(-)