Pull xen updates from Juergen Gross:
 "A small series for fixing a problem with Xen PVH guests when running
  as backends (e.g. as dom0).

  Mapping other guests' memory is now working via ZONE_DEVICE, thus not
  requiring to abuse the memory hotplug functionality for that purpose"

* tag 'for-linus-5.9-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: add helpers to allocate unpopulated memory
  memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC
  xen/balloon: add header guard

Pull drm fixes from Dave Airlie:
 "Not much going on this week, nouveau has a display hw bug workaround,
  amdgpu has some PM fixes and CIK regression fixes, one single radeon
  PLL fix, and a couple of i915 display fixes.

  amdgpu:
   - Fix for 32bit systems
   - SW CTF fix
   - Update for Sienna Cichlid
   - CIK bug fixes

  radeon:
   - PLL fix

  i915:
   - Clang build warning fix
   - HDCP fixes

  nouveau:
   - display fixes"

* tag 'drm-fixes-2020-09-04' of git://anongit.freedesktop.org/drm/drm:
  drm/nouveau/kms/nv50-gp1xx: add WAR for EVO push buffer HW bug
  drm/nouveau/kms/nv50-gp1xx: disable notifies again after core update
  drm/nouveau/kms/nv50-: add some whitespace before debug message
  drm/nouveau/kms/gv100-: Include correct push header in crcc37d.c
  drm/radeon: Prefer lower feedback dividers
  drm/amdgpu: Fix bug in reporting voltage for CIK
  drm/amdgpu: Specify get_argument function for ci_smu_funcs
  drm/amd/pm: enable MP0 DPM for sienna_cichlid
  drm/amd/pm: avoid false alarm due to confusing softwareshutdowntemp setting
  drm/amd/pm: fix is_dpm_running() run error on 32bit system
  drm/i915: Clear the repeater bit on HDCP disable
  drm/i915: Fix sha_text population code
  drm/i915/display: Ensure that ret is always initialized in icl_combo_phy_verify_state

Merge emailed patches from Peter Xu:
 "This is a small series that I picked up from Linus's suggestion to
  simplify cow handling (and also make it more strict) by checking
  against page refcounts rather than mapcounts.

  This makes uffd-wp work again (verified by running upmapsort)"

Note: this is horrendously bad timing, and making this kind of
fundamental vm change after -rc3 is not at all how things should work.
The saving grace is that it really is a a nice simplification:

 8 files changed, 29 insertions(+), 120 deletions(-)

The reason for the bad timing is that it turns out that commit
17839856fd58 ("gup: document and work around 'COW can break either way'
issue" broke not just UFFD functionality (as Peter noticed), but Mikulas
Patocka also reports that it caused issues for strace when running in a
DAX environment with ext4 on a persistent memory setup.

And we can't just revert that commit without re-introducing the original
issue that is a potential security hole, so making COW stricter (and in
the process much simpler) is a step to then undoing the forced COW that
broke other uses.

Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/

* emailed patches from Peter Xu <peterx@redhat.com>:
  mm: Add PGREUSE counter
  mm/gup: Remove enfornced COW mechanism
  mm/ksm: Remove reuse_ksm_page()
  mm: do_wp_page() simplification

With the more strict (but greatly simplified) page reuse logic in
do_wp_page(), we can safely go back to the world where cow is not
enforced with writes.

This essentially reverts commit 17839856fd58 ("gup: document and work
around 'COW can break either way' issue").  There are some context
differences due to some changes later on around it:

  2170ecfa7688 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03)
  376a34efa4ee ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03)

Some lines moved back and forth with those, but this revert patch should
have striped out and covered all the enforced cow bits anyways.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

To be used in order to create foreign mappings. This is based on the
ZONE_DEVICE facility which is used by persistent memory devices in
order to create struct pages and kernel virtual mappings for the IOMEM
areas of such devices. Note that on kernels without support for
ZONE_DEVICE Xen will fallback to use ballooned pages in order to
create foreign mappings.

The newly added helpers use the same parameters as the existing
{alloc/free}_xenballooned_pages functions, which allows for in-place
replacement of the callers. Once a memory region has been added to be
used as scratch mapping space it will no longer be released, and pages
returned are kept in a linked list. This allows to have a buffer of
pages and prevents resorting to frequent additions and removals of
regions.

If enabled (because ZONE_DEVICE is supported) the usage of the new
functionality untangles Xen balloon and RAM hotplug from the usage of
unpopulated physical memory ranges to map foreign pages, which is the
correct thing to do in order to avoid mappings of foreign pages depend
on memory hotplug.

Note the driver is currently not enabled on Arm platforms because it
would interfere with the identity mapping required on some platforms.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20200901083326.21264-4-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>

A couple of minor fixes to the display changes that went in for 5.9.
The most important of which is a workaround for a HW bug that was
exposed by better push buffer space management, leading to
random(ish...) display engine hangs.

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Ben Skeggs <skeggsb@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CACAvsv5QDxyMihrxbPk+-sORnaYtjR6_dbM68gEhb2wxht_G1w@mail.gmail.com

drm/i915 fixes for v5.9-rc4:
- Clang build warning fix
- HDCP fixes

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/87sgbz2pnx.fsf@intel.com

Thanks to NVIDIA for confirming this workaround, and clarifying which HW
is affected.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Tested-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>

This was lost during the header conversion.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>