Pull powerpc fix from Michael Ellerman:
 "One regression fix.

  Changes we merged to STRICT_KERNEL_RWX on 32-bit were causing crashes
  under load on some machines depending on memory layout.

  Thanks to Christophe Leroy"

* tag 'powerpc-5.1-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32s: Fix BATs setting with CONFIG_STRICT_KERNEL_RWX

Pull KVM fixes from Paolo Bonzini:

 - PPC and ARM bugfixes from submaintainers

 - Fix old Windows versions on AMD (recent regression)

 - Fix old Linux versions on processors without EPT

 - Fixes for LAPIC timer optimizations

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (21 commits)
  KVM: nVMX: Fix size checks in vmx_set_nested_state
  KVM: selftests: make hyperv_cpuid test pass on AMD
  KVM: lapic: Check for in-kernel LAPIC before deferencing apic pointer
  KVM: fix KVM_CLEAR_DIRTY_LOG for memory slots of unaligned size
  x86/kvm/mmu: reset MMU context when 32-bit guest switches PAE
  KVM: x86: Whitelist port 0x7e for pre-incrementing %rip
  Documentation: kvm: fix dirty log ioctl arch lists
  KVM: VMX: Move RSB stuffing to before the first RET after VM-Exit
  KVM: arm/arm64: Don't emulate virtual timers on userspace ioctls
  kvm: arm: Skip stage2 huge mappings for unaligned ipa backed by THP
  KVM: arm/arm64: Ensure vcpu target is unset on reset failure
  KVM: lapic: Convert guest TSC to host time domain if necessary
  KVM: lapic: Allow user to disable adaptive tuning of timer advancement
  KVM: lapic: Track lapic timer advance per vCPU
  KVM: lapic: Disable timer advancement if adaptive tuning goes haywire
  x86: kvm: hyper-v: deal with buggy TLB flush requests from WS2012
  KVM: x86: Consider LAPIC TSC-Deadline timer expired if deadline too short
  KVM: PPC: Book3S: Protect memslots while validating user address
  KVM: PPC: Book3S HV: Perserve PSSCR FAKE_SUSPEND bit on guest exit
  KVM: arm/arm64: vgic-v3: Retire pending interrupts on disabling LPIs
  ...

Serge reported some crashes with CONFIG_STRICT_KERNEL_RWX enabled
on a book3s32 machine.

Analysis shows two issues:
  - BATs addresses and sizes are not properly aligned.
  - There is a gap between the last address covered by BATs and the
    first address covered by pages.

Memory mapped with DBATs:
0: 0xc0000000-0xc07fffff 0x00000000 Kernel RO coherent
1: 0xc0800000-0xc0bfffff 0x00800000 Kernel RO coherent
2: 0xc0c00000-0xc13fffff 0x00c00000 Kernel RW coherent
3: 0xc1400000-0xc23fffff 0x01400000 Kernel RW coherent
4: 0xc2400000-0xc43fffff 0x02400000 Kernel RW coherent
5: 0xc4400000-0xc83fffff 0x04400000 Kernel RW coherent
6: 0xc8400000-0xd03fffff 0x08400000 Kernel RW coherent
7: 0xd0400000-0xe03fffff 0x10400000 Kernel RW coherent

Memory mapped with pages:
0xe1000000-0xefffffff  0x21000000       240M        rw       present           dirty  accessed

This patch fixes both issues. With the patch, we get the following
which is as expected:

Memory mapped with DBATs:
0: 0xc0000000-0xc07fffff 0x00000000 Kernel RO coherent
1: 0xc0800000-0xc0bfffff 0x00800000 Kernel RO coherent
2: 0xc0c00000-0xc0ffffff 0x00c00000 Kernel RW coherent
3: 0xc1000000-0xc1ffffff 0x01000000 Kernel RW coherent
4: 0xc2000000-0xc3ffffff 0x02000000 Kernel RW coherent
5: 0xc4000000-0xc7ffffff 0x04000000 Kernel RW coherent
6: 0xc8000000-0xcfffffff 0x08000000 Kernel RW coherent
7: 0xd0000000-0xdfffffff 0x10000000 Kernel RW coherent

Memory mapped with pages:
0xe0000000-0xefffffff  0x20000000       256M        rw       present           dirty  accessed

Fixes: 63b2bc619565 ("powerpc/mm/32s: Use BATs for STRICT_KERNEL_RWX")
Reported-by: Serge Belyshev <belyshev@depni.sinp.msu.ru>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Pull powerpc fixes from Michael Ellerman:
 "A one-liner to make our Radix MMU support depend on HUGETLB_PAGE. We
  use some of the hugetlb inlines (eg. pud_huge()) when operating on the
  linear mapping and if they're compiled into empty wrappers we can
  corrupt memory.

  Then two fixes to our VFIO IOMMU code. The first is not a regression
  but fixes the locking to avoid a user-triggerable deadlock.

  The second does fix a regression since rc1, and depends on the first
  fix. It makes it possible to run guests with large amounts of memory
  again (~256GB).

  Thanks to Alexey Kardashevskiy"

* tag 'powerpc-5.1-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm_iommu: Allow pinning large regions
  powerpc/mm_iommu: Fix potential deadlock
  powerpc/mm/radix: Make Radix require HUGETLB_PAGE

Pull syscall numbering updates from Arnd Bergmann:
 "arch: add pidfd and io_uring syscalls everywhere

  This comes a bit late, but should be in 5.1 anyway: we want the newly
  added system calls to be synchronized across all architectures in the
  release.

  I hope that in the future, any newly added system calls can be added
  to all architectures at the same time, and tested there while they are
  in linux-next, avoiding dependencies between the architecture
  maintainer trees and the tree that contains the new system call"

* tag 'syscalls-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  arch: add pidfd and io_uring syscalls everywhere

KVM/PPC fixes for 5.1

- Fix host hang in the HTM assist code for POWER9
- Take srcu read lock around memslot lookup

When called with vmas_arg==NULL, get_user_pages_longterm() allocates
an array of nr_pages*8 which can easily get greater that the max order,
for example, registering memory for a 256GB guest does this and fails
in __alloc_pages_nodemask().

This adds a loop over chunks of entries to fit the max order limit.

Fixes: 678e174c4c16 ("powerpc/mm/iommu: allow migration of cma allocated pages during mm_iommu_do_alloc", 2019-03-05)
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Currently mm_iommu_do_alloc() is called in 2 cases:
- VFIO_IOMMU_SPAPR_REGISTER_MEMORY ioctl() for normal memory:
	this locks &mem_list_mutex and then locks mm::mmap_sem
	several times when adjusting locked_vm or pinning pages;
- vfio_pci_nvgpu_regops::mmap() for GPU memory:
	this is called with mm::mmap_sem held already and it locks
	&mem_list_mutex.

So one can craft a userspace program to do special ioctl and mmap in
2 threads concurrently and cause a deadlock which lockdep warns about
(below).

We did not hit this yet because QEMU constructs the machine in a single
thread.

This moves the overlap check next to where the new entry is added and
reduces the amount of time spent with &mem_list_mutex held.

This moves locked_vm adjustment from under &mem_list_mutex.

This relies on mm_iommu_adjust_locked_vm() doing nothing when entries==0.

This is one of the lockdep warnings:

======================================================
WARNING: possible circular locking dependency detected
5.1.0-rc2-le_nv2_aikATfstn1-p1 #363 Not tainted
------------------------------------------------------
qemu-system-ppc/8038 is trying to acquire lock:
000000002ec6c453 (mem_list_mutex){+.+.}, at: mm_iommu_do_alloc+0x70/0x490

but task is already holding lock:
00000000fd7da97f (&mm->mmap_sem){++++}, at: vm_mmap_pgoff+0xf0/0x160

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_sem){++++}:
       lock_acquire+0xf8/0x260
       down_write+0x44/0xa0
       mm_iommu_adjust_locked_vm.part.1+0x4c/0x190
       mm_iommu_do_alloc+0x310/0x490
       tce_iommu_ioctl.part.9+0xb84/0x1150 [vfio_iommu_spapr_tce]
       vfio_fops_unl_ioctl+0x94/0x430 [vfio]
       do_vfs_ioctl+0xe4/0x930
       ksys_ioctl+0xc4/0x110
       sys_ioctl+0x28/0x80
       system_call+0x5c/0x70

-> #0 (mem_list_mutex){+.+.}:
       __lock_acquire+0x1484/0x1900
       lock_acquire+0xf8/0x260
       __mutex_lock+0x88/0xa70
       mm_iommu_do_alloc+0x70/0x490
       vfio_pci_nvgpu_mmap+0xc0/0x130 [vfio_pci]
       vfio_pci_mmap+0x198/0x2a0 [vfio_pci]
       vfio_device_fops_mmap+0x44/0x70 [vfio]
       mmap_region+0x5d4/0x770
       do_mmap+0x42c/0x650
       vm_mmap_pgoff+0x124/0x160
       ksys_mmap_pgoff+0xdc/0x2f0
       sys_mmap+0x40/0x80
       system_call+0x5c/0x70

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_sem);
                               lock(mem_list_mutex);
                               lock(&mm->mmap_sem);
  lock(mem_list_mutex);

 *** DEADLOCK ***

1 lock held by qemu-system-ppc/8038:
 #0: 00000000fd7da97f (&mm->mmap_sem){++++}, at: vm_mmap_pgoff+0xf0/0x160

Fixes: c10c21efa4bc ("powerpc/vfio/iommu/kvm: Do not pin device memory", 2018-12-19)
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Joel reported weird crashes using skiroot_defconfig, in his case we
jumped into an NX page:

  kernel tried to execute exec-protected page (c000000002bff4f0) - exploit attempt? (uid: 0)
  BUG: Unable to handle kernel instruction fetch
  Faulting instruction address: 0xc000000002bff4f0

Looking at the disassembly, we had simply branched to that address:

  c000000000c001bc  49fff335    bl     c000000002bff4f0

But that didn't match the original kernel image:

  c000000000c001bc  4bfff335    bl     c000000000bff4f0 <kobject_get+0x8>

When STRICT_KERNEL_RWX is enabled, and we're using the radix MMU, we
call radix__change_memory_range() late in boot to change page
protections. We do that both to mark rodata read only and also to mark
init text no-execute. That involves walking the kernel page tables,
and clearing _PAGE_WRITE or _PAGE_EXEC respectively.

With radix we may use hugepages for the linear mapping, so the code in
radix__change_memory_range() uses eg. pmd_huge() to test if it has
found a huge mapping, and if so it stops the page table walk and
changes the PMD permissions.

However if the kernel is built without HUGETLBFS support, pmd_huge()
is just a #define that always returns 0. That causes the code in
radix__change_memory_range() to incorrectly interpret the PMD value as
a pointer to a PTE page rather than as a PTE at the PMD level.

We can see this using `dv` in xmon which also uses pmd_huge():

  0:mon> dv c000000000000000
  pgd  @ 0xc000000001740000
  pgdp @ 0xc000000001740000 = 0x80000000ffffb009
  pudp @ 0xc0000000ffffb000 = 0x80000000ffffa009
  pmdp @ 0xc0000000ffffa000 = 0xc00000000000018f   <- this is a PTE
  ptep @ 0xc000000000000100 = 0xa64bb17da64ab07d   <- kernel text

The end result is we treat the value at 0xc000000000000100 as a PTE
and clear _PAGE_WRITE or _PAGE_EXEC, potentially corrupting the code
at that address.

In Joel's specific case we cleared the sign bit in the offset of the
branch, causing a backward branch to turn into a forward branch which
caused us to branch into a non-executable page. However the exact
nature of the crash depends on kernel version, compiler version, and
other factors.

We need to fix radix__change_memory_range() to not use accessors that
depend on HUGETLBFS, but we also have radix memory hotplug code that
uses pmd_huge() etc that will also need fixing. So for now just
disallow the broken combination of Radix with HUGETLBFS disabled.

The only defconfig we have that is affected is skiroot_defconfig, so
turn on HUGETLBFS there so that it still gets Radix.

Fixes: 566ca99af026 ("powerpc/mm/radix: Add dummy radix_enabled()")
Cc: stable@vger.kernel.org # v4.7+
Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add the io_uring and pidfd_send_signal system calls to all architectures.

These system calls are designed to handle both native and compat tasks,
so all entries are the same across architectures, only arm-compat and
the generic tale still use an old format.

Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> (s390)
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>