linux-kernel - [PATCH v2 0/3] virtio-mem: disallow mapping virtio-mem memory via /dev/mem

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Date:   Mon, 16 Aug 2021 16:25:02 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org
Subject: [PATCH v2 0/3] virtio-mem: disallow mapping virtio-mem memory via /dev/mem

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.

v1 -> v2:
- "/dev/mem: disallow access to explicitly excluded system RAM regions"
-- Introduce and use for_each_resource() and next_resource_skip_children()
-- s/iomem_range_contains_excluded/iomem_range_contains_excluded_devmem/
- "kernel/resource: cleanup and optimize iomem_is_exclusive()"
-- Use for_each_resource()

Cc: Arnd Bergmann <arnd@...db.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Hanjun Guo <guohanjun@...wei.com>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: virtualization@...ts.linux-foundation.org
Cc: linux-mm@...ck.org

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           | 60 +++++++++++++++++++++++++++++++++----
 lib/Kconfig.debug           |  4 ++-
 5 files changed, 71 insertions(+), 20 deletions(-)

base-commit: 7c60610d476766e128cc4284bb6349732cbd6606
-- 
2.31.1