When resizing a vt its selection may exceed the new size, resulting in
an invalid memory access [1]. Clear the selection before resizing.

[1] http://lkml.kernel.org/r/CACT4Y+acDTwy4umEvf5ROBGiRJNrxHN4Cn5szCXE5Jw-d1B=Xw@mail.gmail.comReported-and-tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Scot Doyle <lkml14@scotdoyle.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The regmap_update first reads the IOState register and then triggers
a write if needed. However, GPIOS might be configured as an input so
 the read to IOState on this GPIO is the current state which might
be random.
Signed-off-by: Francois Berder <Francois.Berder@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Renesas RZ/G SoC also have the SCIF, SCIFA, SCIFB, and HSCIF ports and
they  seem compatible with the R-Car gen2 SoC  in this respect...
Document RZ/G1[ME] (also known as R8A774[35]) SoC bindings.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

NXP SC16C2552 requires that we always write a reset to the RX FIFO and
TX FIFO whenever we enable the FIFOs

Cc: xe-kernel@external.cisco.com
Signed-off-by: Steve Shih <sshih@cisco.com>
Signed-off-by: David Singleton <davsingl@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Size of kmalloc() in vc_do_resize() is controlled by user.
Too large kmalloc() size triggers WARNING message on console.
Put a reasonable upper bound on terminal size to prevent WARNINGs.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
CC: David Rientjes <rientjes@google.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: linux-kernel@vger.kernel.org
Cc: syzkaller@googlegroups.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In the case where head == 0 on the circular buffer, there should be one
DMA buffer, not two.  The second zero-length buffer would break the
lpuart driver, transfer would never complete.
Signed-off-by: Aaron Brice <aaron.brice@datasoft.com>
Acked-by: Stefan Agner <stefan@agner.ch>
Tested-by: Stefan Agner <stefan@agner.ch>
Tested-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The commit 4fe0d154 ("PCI: Use positive flags in pci_alloc_irq_vectors()")
replaces flags from negative to positive values which makes mandatory to have
the last argument in pci_alloc_irq_vectors() non-zero (if we want to be no-op).
This basically drops MSI enabling in 8250_lpss driver.

Restore desired behaviour in 8250_lpss by passing PCI_IRQ_ALL_TYPES instead of
0 to pci_alloc_irq_vectors().

Fixes: 60a9244a ("serial: 8250_lpss: enable MSI for Intel Quark")
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 761ed4a9 ('tty: serial_core: convert uart_close to use
tty_port_close') started setting the ttyport console flag for serial
drivers. This is causing crashes, hangs, or garbage output on several
platforms because the serial shutdown is skipped and IRQs are left
enabled.

Partially revert commit 761ed4a9 and drop reporting UART tty_ports
as a console leaving the console handling to the serial_core as it was
before.

Fixes: 761ed4a9 ("tty: serial_core: convert uart_close to use tty_port_close")
Reported-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Reported-by: Mugunthan V N <mugunthanvnm@ti.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

At this point, 'value' is always a byte, then this code is clearing
bit 15, which is already clear.  I meant to clear bit 7.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 1681d211 ("serial: 8250_uniphier: add "\n" at the end of
error log") missed this.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
[masahiro: add commit log]
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure dmi_system_id tables are NULL terminated.
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch Adds the new compatible string for ZynqMP SoC.
Signed-off-by: Nava kishore Manne <navam@xilinx.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch Adds the new compatible string for ZynqMP SoC.
Signed-off-by: Nava kishore Manne <navam@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If NO_DMA=y:

    drivers/built-in.o: In function `stm32_serial_remove':
    stm32-usart.c:(.text+0xcea1a): undefined reference to `bad_dma_ops'
    stm32-usart.c:(.text+0xcea7a): undefined reference to `bad_dma_ops'

Add a dependency on HAS_DMA to fix this.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    drivers/tty/serial/stm32-usart.c: In function ‘stm32_receive_chars’:
    drivers/tty/serial/stm32-usart.c:130: warning: comparison is always true due to limited range of data type
    drivers/tty/serial/stm32-usart.c: In function ‘stm32_tx_dma_complete’:
    drivers/tty/serial/stm32-usart.c:177: warning: comparison is always false due to limited range of data type

stm32_usart_offsets.icr is u8, while UNDEF_REG = ~0 is int, and thus
0xffffffff.

As all registers in stm32_usart_offsets are u8, change the definition of
UNDEF_REG to 0xff to fix this.

Fixes: ada8618f ("serial: stm32: adding support for stm32f7")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In csi_J(3), the third parameter of scr_memsetw (vc_screenbuf_size) is
divided by 2 inappropriatelly. But scr_memsetw expects size, not
count, because it divides the size by 2 on its own before doing actual
memset-by-words.

So remove the bogus division.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Petr Písař <ppisar@redhat.com>
Fixes: f8df13e0 (tty: Clean console safely)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull UBI[FS] fixes from Richard Weinberger:
 "This contains fixes for issues in both UBI and UBIFS:

   - Fallout from the merge window, refactoring UBI code introduced some
     issues.

   - Fixes for an UBIFS readdir bug which can cause getdents() to busy
     loop for ever and a bug in the UBIFS xattr code"

* tag 'upstream-4.9-rc2' of git://git.infradead.org/linux-ubifs:
  ubifs: Abort readdir upon error
  UBI: Fix crash in try_recover_peb()
  ubi: fix swapped arguments to call to ubi_alloc_aeb
  ubifs: Fix xattr_names length in exit paths
  ubifs: Rename ubifs_rename2

Pull ext4 fixes from Ted Ts'o:
 "A few bug fixes and add some missing KERN_CONT annotations"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: add missing KERN_CONT to a few more debugging uses
  fscrypto: lock inode while setting encryption policy
  ext4: correct endianness conversion in __xattr_check_inode()
  fscrypto: make XTS tweak initialization endian-independent
  ext4: do not advertise encryption support when disabled
  jbd2: fix incorrect unlock on j_list_lock
  ext4: super.c: Update logging style using KERN_CONT

Pull SCSI target fixes from Nicholas Bellinger:
 "Here are the outstanding target-pending fixes for v4.9-rc2.

  This includes:

   - Fix v4.1.y+ reference leak regression with concurrent TMR
     ABORT_TASK + session shutdown. (Vaibhav Tandon)

   - Enable tcm_fc w/ SCF_USE_CPUID to avoid host exchange timeouts
     (Hannes)

   - target/user error sense handling fixes. (Andy + MNC + HCH)

   - Fix iscsi-target NOP_OUT error path iscsi_cmd descriptor leak
     (Varun)

   - Two EXTENDED_COPY SCSI status fixes for ESX VAAI (Dinesh Israni +
     Nixon Vincent)

   - Revert a v4.8 residual overflow change, that breaks sg_inq with
     small allocation lengths.

  There are a number of folks stress testing the v4.1.y regression fix
  in their environments, and more folks doing iser-target I/O stress
  testing atop recent v4.x.y code.

  There is also one v4.2.y+ RCU conversion regression related to
  explicit NodeACL configfs changes, that is still being tracked down"

* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  target/tcm_fc: use CPU affinity for responses
  target/tcm_fc: Update debugging statements to match libfc usage
  target/tcm_fc: return detailed error in ft_sess_create()
  target/tcm_fc: print command pointer in debug message
  target: fix potential race window in target_sess_cmd_list_waiting()
  Revert "target: Fix residual overflow handling in target_complete_cmd_with_length"
  target: Don't override EXTENDED_COPY xcopy_pt_cmd SCSI status code
  target: Make EXTENDED_COPY 0xe4 failure return COPY TARGET DEVICE NOT REACHABLE
  target: Re-add missing SCF_ACK_KREF assignment in v4.1.y
  iscsi-target: fix iscsi cmd leak
  iscsi-target: fix spelling mistake "Unsolicitied" -> "Unsolicited"
  target/user: Fix comments to not refer to data ring
  target/user: Return an error if cmd data size is too large
  target/user: Use sense_reason_t in tcmu_queue_cmd_ring

Merge tag 'hwmon-for-linus-v4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fixes from Guenter Roeck:
 "Couple of hwmon fixes:

  Fix a potential ERR_PTR dereference in max31790 driver, and handle
  temperature readings below 0 in adm9240 driver"

* tag 'hwmon-for-linus-v4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (max31790) potential ERR_PTR dereference
  hwmon: (adm9240) handle temperature readings below 0

Pull IPMI updates from Corey Minyard:
 "A small bug fix and a new driver for acting as an IPMI device.

  I was on vacation during the merge window (a long vacation) but this
  is a bug fix that should go in and a new driver that shouldn't hurt
  anything.

  This has been in linux-next for a month or so"

* tag 'for-linus-4.9-2' of git://git.code.sf.net/p/openipmi/linux-ipmi:
  ipmi: fix crash on reading version from proc after unregisted bmc
  ipmi/bt-bmc: remove redundant return value check of platform_get_resource()
  ipmi/bt-bmc: add a dependency on ARCH_ASPEED
  ipmi: Fix ioremap error handling in bt-bmc
  ipmi: add an Aspeed BT IPMI BMC driver

Pull timer updates from Thomas Gleixner:
 "This updates contains:

   - A revert which addresses a boot failure on ARM Sun5i platforms

   - A new clocksource driver, which has been delayed beyond rc1 due to
     an interrupt driver issue which was unearthed by this driver. The
     debugging of that issue and the discussion about the proper
     solution made this driver miss the merge window. There is no point
     in delaying it for a full cycle as it completes the basic mainline
     support for the new JCore platform and does not create any risk
     outside of that platform"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "clocksource/drivers/timer_sun5i: Replace code by clocksource_mmio_init"
  clocksource: Add J-Core timer/clocksource driver
  of: Add J-Core timer bindings

Pull x86 fixes from Ingo Molnar:
 "Three fixes, a hw-enablement and a cross-arch fix/enablement change:

   - SGI/UV fix for older platforms

   - x32 signal handling fix

   - older x86 platform bootup APIC fix

   - AVX512-4VNNIW (Neural Network Instructions) and AVX512-4FMAPS
     (Multiply Accumulation Single precision instructions) enablement.

   - move thread_info back into x86 specific code, to make life easier
     for other architectures trying to make use of
     CONFIG_THREAD_INFO_IN_TASK_STRUCT=y"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot/smp: Don't try to poke disabled/non-existent APIC
  sched/core, x86: Make struct thread_info arch specific again
  x86/signal: Remove bogus user_64bit_mode() check from sigaction_compat_abi()
  x86/platform/UV: Fix support for EFI_OLD_MEMMAP after BIOS callback updates
  x86/cpufeature: Add AVX512_4VNNIW and AVX512_4FMAPS features
  x86/vmware: Skip timer_irq_works() check on VMware

Pull vmap stack fixes from Ingo Molnar:
 "This is fallout from CONFIG_HAVE_ARCH_VMAP_STACK=y on x86: stack
  accesses that used to be just somewhat questionable are now totally
  buggy.

  These changes try to do it without breaking the ABI: the fields are
  left there, they are just reporting zero, or reporting narrower
  information (the maps file change)"

* 'mm-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  mm: Change vm_is_stack_for_task() to vm_is_stack_for_current()
  fs/proc: Stop trying to report thread stacks
  fs/proc: Stop reporting eip and esp in /proc/PID/stat
  mm/numa: Remove duplicated include from mprotect.c

Pull irq fixes from Ingo Molnar:
 "Mostly irqchip driver fixes, plus a symbol export"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kernel/irq: Export irq_set_parent()
  irqchip/gic: Add missing \n to CPU IF adjustment message
  irqchip/jcore: Don't show Kconfig menu item for driver
  irqchip/eznps: Drop pointless static qualifier in nps400_of_init()
  irqchip/gic-v3-its: Fix entry size mask for GITS_BASER
  irqchip/gic-v3-its: Fix 64bit GIC{R,ITS}_TYPER accesses

Pull EFI fixes from Ingo Molnar:
 "Add Ard Biesheuvel as EFI co-maintainer, plus fix an ARM build bug
  with older toolchains"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/arm: Fix absolute relocation detection for older toolchains
  MAINTAINERS: Add myself as EFI maintainer

Apparently trying to poke a disabled or non-existent APIC
leads to a box that doesn't even boot. Let's not do that.

No real clue if this is the right fix, but at least my
P3 machine boots again.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: dyoung@redhat.com
Cc: kexec@lists.infradead.org
Cc: stable@vger.kernel.org
Fixes: 2a51fe08 ("arch/x86: Handle non enumerated CPU after physical hotplug")
Link: http://lkml.kernel.org/r/1477102684-5092-1-git-send-email-ville.syrjala@linux.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

Pull powerpc fixes from Michael Ellerman:
 "Fixes marked for stable:
   - Prevent unlikely crash in copro_calculate_slb() (Frederic Barrat)
   - cxl: Prevent adapter reset if an active context exists (Vaibhav Jain)

  Fixes for code merged this cycle:
   - Fix boot on systems with uncompressed kernel image (Heiner Kallweit)
   - Drop dump_numa_memory_topology() (Michael Ellerman)
   - Fix numa topology console print (Aneesh Kumar K.V)
   - Ignore the pkey system calls for now (Stephen Rothwell)"

* tag 'powerpc-4.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: Ignore the pkey system calls for now
  powerpc: Fix numa topology console print
  powerpc/mm: Drop dump_numa_memory_topology()
  cxl: Prevent adapter reset if an active context exists
  powerpc/boot: Fix boot on systems with uncompressed kernel image
  powerpc/mm: Prevent unlikely crash in copro_calculate_slb()

Pull KVM fixes from Radim Krčmář:
 "ARM:
   - avoid livelock when walking guest page tables
   - fix HYP mode static keys without CC_HAVE_ASM_GOTO

  MIPS:
   - fix a build error without TRACEPOINTS_ENABLED

  s390:
   - reject a malformed userspace configuration

  x86:
   - suppress a warning without CONFIG_CPU_FREQ
   - initialize whole irq_eoi array"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  arm/arm64: KVM: Map the BSS at HYP
  arm64: KVM: Take S1 walks into account when determining S2 write faults
  KVM: s390: reject invalid modes for runtime instrumentation
  kvm: x86: memset whole irq_eoi
  kvm/x86: Fix unused variable warning in kvm_timer_init()
  KVM: MIPS: Add missing uaccess.h include

Pull NFS client bugfixes from Anna Schumaker:
 "Just two bugfixes this time:

  Stable bugfix:
   - Fix last_write_offset incorrectly set to page boundary

  Other bugfix:
   - Fix missing-braces warning"

* tag 'nfs-for-4.9-2' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  nfs4: fix missing-braces warning
  pnfs/blocklayout: fix last_write_offset incorrectly set to page boundary

Pull ACPI fixes from Rafael Wysocki:
 "These fix an issue related to system resume in the new WDAT-based
  watchdog driver and a return value of a stub function in the ACPI CPPC
  framework.

  Specifics:

   - Update the ACPI WDAT-based watchdog driver to ping the hardware
     during system resume to prevent a reset from occurring after the
     resume is complete (Mika Westerberg).

   - Fix the return value of the pcc_mbox_request_channel() stub for
     CONFIG_PCC unset (Hoan Tran)"

* tag 'acpi-4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  watchdog: wdat_wdt: Ping the watchdog on resume
  mailbox: PCC: Fix return value of pcc_mbox_request_channel()

* acpi-wdat:
  watchdog: wdat_wdt: Ping the watchdog on resume

* acpi-cppc:
  mailbox: PCC: Fix return value of pcc_mbox_request_channel()

Merge tag 'gic-fixes-for-4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Pull GIC updates from Marc Zyngier:

 - Fix for 32bit accesses that should be 64bit on 64bit machines
 - Fix for a field decoding macro
 - Beautify a warning message

Pull SCSI fixes from James Bottomley:
 "Five small fixes.

  Some of these, like the nested spinlock overwriting saved flags and
  the Kasan use after free look serious, but they seem not to have been
  picked up in testing or seen in the field.

  The biggest user visible issue is probably the wrong device handler
  for Clariion, which means that alua doesn't bind to the array like it
  should"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ipr: Fix async error WARN_ON
  scsi: zfcp: spin_lock_irqsave() is not nestable
  scsi: Remove one useless stack variable
  scsi: Fix use-after-free
  scsi: Replace wrong device handler name for CLARiiON arrays

Pull block fixes from Jens Axboe:
 "A set of fixes that missed the merge window, mostly due to me being
  away around that time.

  Nothing major here, a mix of nvme cleanups and fixes, and one fix for
  the badblocks handling"

* 'for-linus' of git://git.kernel.dk/linux-block:
  nvmet: use symbolic constants for CNS values
  nvme: use symbolic constants for CNS values
  nvme.h: add an enum for cns values
  nvme.h: don't use uuid_be
  nvme.h: resync with nvme-cli
  nvme: Add tertiary number to NVME_VS
  nvme : Add sysfs entry for NVMe CMBs when appropriate
  nvme: don't schedule multiple resets
  nvme: Delete created IO queues on reset
  nvme: Stop probing a removed device
  badblocks: fix overlapping check for clearing

Pull PCI fixes from Bjorn Helgaas:
 "This includes:

   - Fix for a Layerscape driver issue that causes a use-before-set
     crash

   - Maintainer update for the Synopsis prototyping device driver"

* tag 'pci-v4.9-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: designware-plat: Update author email address
  PCI: layerscape: Fix drvdata usage before assignment
  PCI: designware-plat: Change maintainer to Jose Abreu

KVM/ARM updates for 4.9-rc2

- Handle faults generated by the page table walker as being writes
- Map the BSS at EL2

When used with a compiler that doesn't implement "asm goto"
(such as the AArch64 port of GCC 4.8), jump labels generate a
memory access to find out about the value of the key (instead
of just patching the code). The key itself is likely to be
stored in the BSS.

This is perfectly fine, except that we don't map the BSS at HYP,
leading to an exploding kernel at the first access. The obvious
fix is simply to map the BSS there (which should have been done
a long while ago, but hey...).
Reported-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

The WnR bit in the HSR/ESR_EL2 indicates whether a data abort was
generated by a read or a write instruction. For stage 2 data aborts
generated by a stage 1 translation table walk (i.e. the actual page
table access faults at EL2), the WnR bit therefore reports whether the
instruction generating the walk was a load or a store, *not* whether the
page table walker was reading or writing the entry.

For page tables marked as read-only at stage 2 (e.g. due to KSM merging
them with the tables from another guest), this could result in livelock,
where a page table walk generated by a load instruction attempts to
set the access flag in the stage 1 descriptor, but fails to trigger
CoW in the host since only a read fault is reported.

This patch modifies the arm64 kvm_vcpu_dabt_iswrite function to
take into account stage 2 faults in stage 1 walks. Since DBM cannot be
disabled at EL2 for CPUs that implement it, we assume that these faults
are always causes by writes, avoiding the livelock situation at the
expense of occasional, spurious CoWs.

We could, in theory, do a bit better by checking the guest TCR
configuration and inspecting the page table to see why the PTE faulted.
However, I doubt this is measurable in practice, and the threat of
livelock is real.

Cc: <stable@vger.kernel.org>
Cc: Julien Grall <julien.grall@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>