Moved sched_litmus back to the top scheduling class

 - This is my first attempt to re-add all of the modifications on top of
   this version of the Linux kernel that were present in the previous
   version of LITMUS.

 - More notes on changes will follow after testing--no guarantees the
   code as it is now will compile or run correctly.

Pull kvm fixes from Paolo Bonzini:
 "Fix unwinding of KVM_CREATE_VM failure, VT-d posted interrupts,
  DAX/ZONE_DEVICE, and module unload/reload"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved
  KVM: VMX: Introduce pi_is_pir_empty() helper
  KVM: VMX: Do not change PID.NDST when loading a blocked vCPU
  KVM: VMX: Consider PID.PIR to determine if vCPU has pending interrupts
  KVM: VMX: Fix comment to specify PID.ON instead of PIR.ON
  KVM: X86: Fix initialization of MSR lists
  KVM: fix placement of refcount initialization
  KVM: Fix NULL-ptr deref after kvm_create_vm fails

Pull x86 TSX Async Abort and iTLB Multihit mitigations from Thomas Gleixner:
 "The performance deterioration departement is not proud at all of
  presenting the seventh installment of speculation mitigations and
  hardware misfeature workarounds:

   1) TSX Async Abort (TAA) - 'The Annoying Affair'

      TAA is a hardware vulnerability that allows unprivileged
      speculative access to data which is available in various CPU
      internal buffers by using asynchronous aborts within an Intel TSX
      transactional region.

      The mitigation depends on a microcode update providing a new MSR
      which allows to disable TSX in the CPU. CPUs which have no
      microcode update can be mitigated by disabling TSX in the BIOS if
      the BIOS provides a tunable.

      Newer CPUs will have a bit set which indicates that the CPU is not
      vulnerable, but the MSR to disable TSX will be available
      nevertheless as it is an architected MSR. That means the kernel
      provides the ability to disable TSX on the kernel command line,
      which is useful as TSX is a truly useful mechanism to accelerate
      side channel attacks of all sorts.

   2) iITLB Multihit (NX) - 'No eXcuses'

      iTLB Multihit is an erratum where some Intel processors may incur
      a machine check error, possibly resulting in an unrecoverable CPU
      lockup, when an instruction fetch hits multiple entries in the
      instruction TLB. This can occur when the page size is changed
      along with either the physical address or cache type. A malicious
      guest running on a virtualized system can exploit this erratum to
      perform a denial of service attack.

      The workaround is that KVM marks huge pages in the extended page
      tables as not executable (NX). If the guest attempts to execute in
      such a page, the page is broken down into 4k pages which are
      marked executable. The workaround comes with a mechanism to
      recover these shattered huge pages over time.

  Both issues come with full documentation in the hardware
  vulnerabilities section of the Linux kernel user's and administrator's
  guide.

  Thanks to all patch authors and reviewers who had the extraordinary
  priviledge to be exposed to this nuisance.

  Special thanks to Borislav Petkov for polishing the final TAA patch
  set and to Paolo Bonzini for shepherding the KVM iTLB workarounds and
  providing also the backports to stable kernels for those!"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs
  Documentation: Add ITLB_MULTIHIT documentation
  kvm: x86: mmu: Recovery of shattered NX large pages
  kvm: Add helper function for creating VM worker threads
  kvm: mmu: ITLB_MULTIHIT mitigation
  cpu/speculation: Uninline and export CPU mitigations helpers
  x86/cpu: Add Tremont to the cpu vulnerability whitelist
  x86/bugs: Add ITLB_MULTIHIT bug infrastructure
  x86/tsx: Add config options to set tsx=on|off|auto
  x86/speculation/taa: Add documentation for TSX Async Abort
  x86/tsx: Add "auto" option to the tsx= cmdline parameter
  kvm/x86: Export MDS_NO=0 to guests when TSX is enabled
  x86/speculation/taa: Add sysfs reporting for TSX Async Abort
  x86/speculation/taa: Add mitigation for TSX Async Abort
  x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default
  x86/cpu: Add a helper function x86_read_arch_cap_msr()
  x86/msr: Add the IA32_TSX_CTRL MSR

Explicitly exempt ZONE_DEVICE pages from kvm_is_reserved_pfn() and
instead manually handle ZONE_DEVICE on a case-by-case basis.  For things
like page refcounts, KVM needs to treat ZONE_DEVICE pages like normal
pages, e.g. put pages grabbed via gup().  But for flows such as setting
A/D bits or shifting refcounts for transparent huge pages, KVM needs to
to avoid processing ZONE_DEVICE pages as the flows in question lack the
underlying machinery for proper handling of ZONE_DEVICE pages.

This fixes a hang reported by Adam Borowski[*] in dev_pagemap_cleanup()
when running a KVM guest backed with /dev/dax memory, as KVM straight up
doesn't put any references to ZONE_DEVICE pages acquired by gup().

Note, Dan Williams proposed an alternative solution of doing put_page()
on ZONE_DEVICE pages immediately after gup() in order to simplify the
auditing needed to ensure is_zone_device_page() is called if and only if
the backing device is pinned (via gup()).  But that approach would break
kvm_vcpu_{un}map() as KVM requires the page to be pinned from map() 'til
unmap() when accessing guest memory, unlike KVM's secondary MMU, which
coordinates with mmu_notifier invalidations to avoid creating stale
page references, i.e. doesn't rely on pages being pinned.

[*] http://lkml.kernel.org/r/20190919115547.GA17963@angband.pl

Reported-by: Adam Borowski <kilobyte@angband.pl>
Analyzed-by: David Hildenbrand <david@redhat.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: stable@vger.kernel.org
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull ARM SoC fixes from Olof Johansson:
 "A set of fixes that have trickled in over the last couple of weeks:

   - MAINTAINER update for Cavium/Marvell ThunderX2

   - stm32 tweaks to pinmux for Joystick/Camera, and RAM allocation for
     CAN interfaces

   - i.MX fixes for voltage regulator GPIO mappings, fixes voltage
     scaling issues

   - More i.MX fixes for various issues on i.MX eval boards: interrupt
     storm due to u-boot leaving pins in new states, fixing power button
     config, a couple of compatible-string corrections.

   - Powerdown and Suspend/Resume fixes for Allwinner A83-based tablets

   - A few documentation tweaks and a fix of a memory leak in the reset
     subsystem"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
  MAINTAINERS: update Cavium ThunderX2 maintainers
  ARM: dts: stm32: change joystick pinctrl definition on stm32mp157c-ev1
  ARM: dts: stm32: remove OV5640 pinctrl definition on stm32mp157c-ev1
  ARM: dts: stm32: Fix CAN RAM mapping on stm32mp157c
  ARM: dts: stm32: relax qspi pins slew-rate for stm32mp157
  arm64: dts: zii-ultra: fix ARM regulator GPIO handle
  ARM: sunxi: Fix CPU powerdown on A83T
  ARM: dts: sun8i-a83t-tbs-a711: Fix WiFi resume from suspend
  arm64: dts: imx8mn: fix compatible string for sdma
  arm64: dts: imx8mm: fix compatible string for sdma
  reset: fix reset_control_ops kerneldoc comment
  ARM: dts: imx6-logicpd: Re-enable SNVS power key
  soc: imx: gpc: fix initialiser format
  ARM: dts: imx6qdl-sabreauto: Fix storm of accelerometer interrupts
  arm64: dts: ls1028a: fix a compatible issue
  reset: fix reset_control_get_exclusive kerneldoc comment
  reset: fix reset_control_lookup kerneldoc comment
  reset: fix of_reset_control_get_count kerneldoc comment
  reset: fix of_reset_simple_xlate kerneldoc comment
  reset: Fix memory leak in reset_control_array_put()

Pull networking fixes from David Miller:

 1) BPF sample build fixes from Björn Töpel

 2) Fix powerpc bpf tail call implementation, from Eric Dumazet.

 3) DCCP leaks jiffies on the wire, fix also from Eric Dumazet.

 4) Fix crash in ebtables when using dnat target, from Florian Westphal.

 5) Fix port disable handling whne removing bcm_sf2 driver, from Florian
    Fainelli.

 6) Fix kTLS sk_msg trim on fallback to copy mode, from Jakub Kicinski.

 7) Various KCSAN fixes all over the networking, from Eric Dumazet.

 8) Memory leaks in mlx5 driver, from Alex Vesker.

 9) SMC interface refcounting fix, from Ursula Braun.

10) TSO descriptor handling fixes in stmmac driver, from Jose Abreu.

11) Add a TX lock to synchonize the kTLS TX path properly with crypto
    operations. From Jakub Kicinski.

12) Sock refcount during shutdown fix in vsock/virtio code, from Stefano
    Garzarella.

13) Infinite loop in Intel ice driver, from Colin Ian King.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (108 commits)
  ixgbe: need_wakeup flag might not be set for Tx
  i40e: need_wakeup flag might not be set for Tx
  igb/igc: use ktime accessors for skb->tstamp
  i40e: Fix for ethtool -m issue on X722 NIC
  iavf: initialize ITRN registers with correct values
  ice: fix potential infinite loop because loop counter being too small
  qede: fix NULL pointer deref in __qede_remove()
  net: fix data-race in neigh_event_send()
  vsock/virtio: fix sock refcnt holding during the shutdown
  net: ethernet: octeon_mgmt: Account for second possible VLAN header
  mac80211: fix station inactive_time shortly after boot
  net/fq_impl: Switch to kvmalloc() for memory allocation
  mac80211: fix ieee80211_txq_setup_flows() failure path
  ipv4: Fix table id reference in fib_sync_down_addr
  ipv6: fixes rt6_probe() and fib6_nh->last_probe init
  net: hns: Fix the stray netpoll locks causing deadlock in NAPI path
  net: usb: qmi_wwan: add support for DW5821e with eSIM support
  CDC-NCM: handle incomplete transfer of MTU
  nfc: netlink: fix double device reference drop
  NFC: st21nfca: fix double free
  ...

Pull XArray fixes from Matthew Wilcox:
 "These all fix various bugs, some of which people have tripped over and
  some of which have been caught by automatic tools"

* tag 'xarray-5.4' of git://git.infradead.org/users/willy/linux-dax:
  idr: Fix idr_alloc_u32 on 32-bit systems
  idr: Fix integer overflow in idr_for_each_entry
  radix tree: Remove radix_tree_iter_find
  idr: Fix idr_get_next_ul race with idr_remove
  XArray: Fix xas_next() with a single entry at 0

We have a usecase to use tmpfs as QEMU memory backend and we would like
to take the advantage of THP as well.  But, our test shows the EPT is
not PMD mapped even though the underlying THP are PMD mapped on host.
The number showed by /sys/kernel/debug/kvm/largepage is much less than
the number of PMD mapped shmem pages as the below:

  7f2778200000-7f2878200000 rw-s 00000000 00:14 262232 /dev/shm/qemu_back_mem.mem.Hz2hSf (deleted)
  Size:            4194304 kB
  [snip]
  AnonHugePages:         0 kB
  ShmemPmdMapped:   579584 kB
  [snip]
  Locked:                0 kB

  cat /sys/kernel/debug/kvm/largepages
  12

And some benchmarks do worse than with anonymous THPs.

By digging into the code we figured out that commit 127393fbe597 ("mm:
thp: kvm: fix memory corruption in KVM with THP enabled") checks if
there is a single PTE mapping on the page for anonymous THP when setting
up EPT map.  But the _mapcount < 0 check doesn't work for page cache THP
since every subpage of page cache THP would get _mapcount inc'ed once it
is PMD mapped, so PageTransCompoundMap() always returns false for page
cache THP.  This would prevent KVM from setting up PMD mapped EPT entry.

So we need handle page cache THP correctly.  However, when page cache
THP's PMD gets split, kernel just remove the map instead of setting up
PTE map like what anonymous THP does.  Before KVM calls get_user_pages()
the subpages may get PTE mapped even though it is still a THP since the
page cache THP may be mapped by other processes at the mean time.

Checking its _mapcount and whether the THP has PTE mapped or not.
Although this may report some false negative cases (PTE mapped by other
processes), it looks not trivial to make this accurate.

With this fix /sys/kernel/debug/kvm/largepage would show reasonable
pages are PMD mapped by EPT as the below:

  7fbeaee00000-7fbfaee00000 rw-s 00000000 00:14 275464 /dev/shm/qemu_back_mem.mem.SKUvat (deleted)
  Size:            4194304 kB
  [snip]
  AnonHugePages:         0 kB
  ShmemPmdMapped:   557056 kB
  [snip]
  Locked:                0 kB

  cat /sys/kernel/debug/kvm/largepages
  271

And the benchmarks are as same as anonymous THPs.

[yang.shi@linux.alibaba.com: v4]
  Link: http://lkml.kernel.org/r/1571865575-42913-1-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1571769577-89735-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: dd78fedde4b9 ("rmap: support file thp")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reported-by: Gang Deng <gavin.dg@linux.alibaba.com>
Tested-by: Gang Deng <gavin.dg@linux.alibaba.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>