Update Documentation for the gcc v4.9 upgrade requirement.

Fixes: 5429ef62 ("compiler/gcc: Raise minimum GCC version for kernel builds to 4.8")
Fixes: 6ec4476a ("Raise gcc version requirement to 4.9")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull sound fixes from Takashi Iwai:
 "A collection of small, mostly device-specific fixes.

  The significant one is the regression fix for USB-audio implicit
  feedback devices due to the incorrect frame size calculation, which
  landed in 5.8 and stable trees.

  In addition, a few usual HD-audio and USB-audio quirks, Intel HDMI
  fixes, ASoC fsl and rt5682 fixes, as well as the fix in
  compress-offload partial drain operation"

* tag 'sound-5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: compress: fix partial_drain completion state
  ALSA: usb-audio: Add implicit feedback quirk for RTX6001
  ALSA: usb-audio: add quirk for MacroSilicon MS2109
  ALSA: hda/realtek: Enable headset mic of Acer Veriton N4660G with ALC269VC
  ALSA: hda/realtek: Enable headset mic of Acer C20-820 with ALC269VC
  ALSA: hda/realtek - Enable audio jacks of Acer vCopperbox with ALC269VC
  ALSA: hda/realtek - Fix Lenovo Thinkpad X1 Carbon 7th quirk subdevice id
  ALSA: hda/hdmi: improve debug traces for stream lookups
  ALSA: hda/hdmi: fix failures at PCM open on Intel ICL and later
  ALSA: opl3: fix infoleak in opl3
  ALSA: usb-audio: Replace s/frame/packet/ where appropriate
  ALSA: usb-audio: Fix packet size calculation
  AsoC: amd: add missing snd- module prefix to the acp3x-rn driver kernel module
  ALSA: hda - let hs_mic be picked ahead of hp_mic
  ASoC: rt5682: fix the pop noise while OMTP type headset plugin
  ASoC: fsl_mqs: Fix unchecked return value for clk_prepare_enable
  ASoC: fsl_mqs: Don't check clock is NULL before calling clk API

I realize that we fairly recently raised it to 4.8, but the fact is, 4.9
is a much better minimum version to target.

We have a number of workarounds for actual bugs in pre-4.9 gcc versions
(including things like internal compiler errors on ARM), but we also
have some syntactic workarounds for lacking features.

In particular, raising the minimum to 4.9 means that we can now just
assume _Generic() exists, which is likely the much better replacement
for a lot of very convoluted built-time magic with conditionals on
sizeof and/or __builtin_choose_expr() with same_type() etc.

Using _Generic also means that you will need to have a very recent
version of 'sparse', but thats easy to build yourself, and much less of
a hassle than some old gcc version can be.

The latest (in a long string) of reasons for minimum compiler version
upgrades was commit 5435f73d ("efi/x86: Fix build with gcc 4").

Ard points out that RHEL 7 uses gcc-4.8, but the people who stay back on
old RHEL versions persumably also don't build their own kernels anyway.
And maybe they should cross-built or just have a little side affair with
a newer compiler?
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull perf tooling fixes from Arnaldo Carvalho de Melo:

 - Intel PT fixes for PEBS-via-PT with registers

 - Fixes for Intel PT python based GUI

 - Avoid duplicated sideband events with Intel PT in system wide tracing

 - Remove needless 'dummy' event from TUI menu, used when synthesizing
   meta data events for pre-existing processes

 - Fix corner case segfault when pressing enter in a screen without
   entries in the TUI for report/top

 - Fixes for time stamp handling in libtraceevent

 - Explicitly set utf-8 encoding in perf flamegraph

 - Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy',
   silencing perf build warning

* tag 'perf-tools-fixes-2020-07-07' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
  perf report TUI: Remove needless 'dummy' event from menu
  perf intel-pt: Fix PEBS sample for XMM registers
  perf intel-pt: Fix displaying PEBS-via-PT with registers
  perf intel-pt: Fix recording PEBS-via-PT with registers
  perf report TUI: Fix segmentation fault in perf_evsel__hists_browse()
  tools lib traceevent: Add proper KBUFFER_TYPE_TIME_STAMP handling
  tools lib traceevent: Add API to read time information from kbuffer
  perf scripts python: exported-sql-viewer.py: Fix time chart call tree
  perf scripts python: exported-sql-viewer.py: Fix zero id in call tree 'Find' result
  perf scripts python: exported-sql-viewer.py: Fix zero id in call graph 'Find' result
  perf scripts python: exported-sql-viewer.py: Fix unexpanded 'Find' result
  perf record: Fix duplicated sideband events with Intel PT system wide tracing
  perf scripts python: export-to-postgresql.py: Fix struct.pack() int argument
  tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy'
  perf flamegraph: Explicitly set utf-8 encoding

Pull MTD fixes from Miquel Raynal:
 "MTD:
   - Set a missing master partition panic write flag

  Raw NAND:
   - Fix build issue in the xway driver
   - Fix a wrong return code"

* tag 'mtd/fixes-for-5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux:
  mtd: rawnand: xway: Fix build issue
  mtd: set master partition panic write flag
  nandsim: Fix return code testing of ns_find_operation()

Pull btrfs fixes from David Sterba:

 - regression fix of a leak in global block reserve accounting

 - fix a (hard to hit) race of readahead vs releasepage that could lead
   to crash

 - convert all remaining uses of comment fall through annotations to the
   pseudo keyword

 - fix crash when mounting a fuzzed image with -o recovery

* tag 'for-5.8-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: reset tree root pointer after error in init_tree_roots
  btrfs: fix reclaim_size counter leak after stealing from global reserve
  btrfs: fix fatal extent_buffer readahead vs releasepage race
  btrfs: convert comments to fallthrough annotations

Pull ARC fixes from Vineet Gupta:

 - User build systems to pass -mcpu

 - Fix potential EFA clobber in syscall handler

 - Fix ARCompact 2 levels of interrupts build

 - Detect newer HS CPU releases

 - misc other fixes

* tag 'arc-5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARCv2: support loop buffer (LPB) disabling
  ARC: build: remove deprecated toggle for arc700 builds
  ARC: build: allow users to specify -mcpu
  ARCv2: boot log: detect newer/upconing HS3x/HS4x releases
  ARC: elf: use right ELF_ARCH
  ARC: [arcompact] fix bitrot with 2 levels of interrupt
  ARC: entry: fix potential EFA clobber when TIF_SYSCALL_TRACE

Pull tpm fix from Jarkko Sakkinen:
 "Revert commit e918e570 ("tpm_tis: Remove the HID IFX0102").

  Removing IFX0102 from tpm_tis was not a right move because both
  tpm_tis and tpm_infineon use the same device ID.

  A real fix requires quirks added to both drivers. It can probably wait
  until v5.9 as the bug has existed since 2006"

* tag 'tpmdd-next-v5.8-rc5' of git://git.infradead.org/users/jjs/linux-tpmdd:
  Revert commit e918e570 ("tpm_tis: Remove the HID IFX0102")

This MIPS driver does not support COMPILE_TEST yet and failed to build
under my radar.

Replace 'mtd' chich is not defined in the scope of xway_nand_remove()
by nand_to_mtd(chip). The mistake has been added in the long series
dropping nand_release().

Tested with a 7.3.0 MIPS GCC toolchain built with Buildroot.

Fixes: 9fdd78f7 ("mtd: rawnand: xway: Stop using nand_release()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200626065511.16424-1-miquel.raynal@bootlin.com

On partial_drain completion we should be in SNDRV_PCM_STATE_RUNNING
state, so set that for partially draining streams in
snd_compr_drain_notify() and use a flag for partially draining streams

While at it, add locks for stream state change in
snd_compr_drain_notify() as well.

Fixes: f44f2a54 ("ALSA: compress: fix drain calls blocking other compress functions (v6)")
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Tested-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20200629134737.105993-4-vkoul@kernel.orgSigned-off-by: Takashi Iwai <tiwai@suse.de>

USB Audio analyzer RTX6001 uses the same implicit feedback quirk
as other XMOS-based devices.
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Tested-by: Pavel Hofman <pavel.hofman@ivitera.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/822f0f20-1886-6884-a6b2-d11c685cbafa@ivitera.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

These devices claim to be 96kHz mono, but actually are 48kHz stereo with
swapped channels and unaligned transfers.

Cc: stable@vger.kernel.org
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20200702071433.237843-1-marcan@marcan.stSigned-off-by: Takashi Iwai <tiwai@suse.de>

The Acer Veriton N4660G desktop's audio (1025:1248) with ALC269VC cannot
detect the headset microphone until ALC269VC_FIXUP_ACER_MIC_NO_PRESENCE
quirk maps the NID 0x18 as the headset mic pin.
Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200706071826.39726-3-jian-hong@endlessm.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

The Acer Aspire C20-820 AIO's audio (1025:1065) with ALC269VC can't
detect the headset microphone until ALC269VC_FIXUP_ACER_HEADSET_MIC
quirk maps the NID 0x18 as the headset mic pin.
Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com>
Signed-off-by: Daniel Drake <drake@endlessm.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200706071826.39726-2-jian-hong@endlessm.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

The Acer desktop vCopperbox with ALC269VC cannot detect the MIC of
headset, the line out and internal speaker until
ALC269VC_FIXUP_ACER_VCOPPERBOX_PINS quirk applied.
Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com>
Signed-off-by: Chris Chiu <chiu@endlessm.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200706071826.39726-1-jian-hong@endlessm.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

1)
In snd_hda_pick_fixup(), quirks are first matched by PCI SSID and then, if
there is no match, by codec SSID. The Lenovo "ThinkPad X1 Carbon 7th" has
an audio chip with PCI SSID 0x2292 and codec SSID 0x2293[1]. Therefore, fix
the quirk meant for that device to match on .subdevice == 0x2292.

2)
The "Thinkpad X1 Yoga 7th" does not exist. The companion product to the
Carbon 7th is the Yoga 4th. That device has an audio chip with PCI SSID
0x2292 and codec SSID 0x2292[2]. Given the behavior of
snd_hda_pick_fixup(), it is not possible to have a separate quirk for the
Yoga based on SSID. Therefore, merge the quirks meant for the Carbon and
Yoga. This preserves the current behavior for the Yoga.

[1] This is the case on my own machine and can also be checked here
https://github.com/linuxhw/LsPCI/tree/master/Notebook/Lenovo/ThinkPad
https://gist.github.com/hamidzr/dd81e429dc86f4327ded7a2030e7d7d9#gistcomment-3225701
[2]
https://github.com/linuxhw/LsPCI/tree/master/Convertible/Lenovo/ThinkPad
https://gist.github.com/hamidzr/dd81e429dc86f4327ded7a2030e7d7d9#gistcomment-3176355

Fixes: d2cd795c ("ALSA: hda - fixup for the bass speaker on Lenovo Carbon X1 7th gen")
Fixes: 54a6a7dc ("ALSA: hda/realtek - Add quirk for the bass speaker on Lenovo Yoga X1 7th gen")
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Kailang Yang <kailang@realtek.com>
Tested-by: Vincent Bernat <vincent@bernat.ch>
Tested-by: Even Brenden <evenbrenden@gmail.com>
Signed-off-by: Benjamin Poirier <benjamin.poirier@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200703080005.8942-2-benjamin.poirier@gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

The HDMI codec driver has two debug traces printed from different
functions but with identical message content:

"HDMI: hinfo 000000006a6b84d9 not registered"

Fix this duplication and also add a bit more context in addition to raw
object pointer, to help analysis of kernel logs.
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20200703153818.2808592-2-kai.vehmanen@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

When HDMI PCM devices are opened in a specific order, with at least one
HDMI/DP receiver connected, ALSA PCM open fails to -EBUSY on the
connected monitor, on recent Intel platforms (ICL/JSL and newer). While
this is not a typical sequence, at least Pulseaudio does this every time
when it is started, to discover the available PCMs.

The rootcause is an invalid assumption in hdmi_add_pin(), where the
total number of converters is assumed to be known at the time the
function is called. On older Intel platforms this held true, but after
ICL/JSL, the order how pins and converters are in the subnode list as
returned by snd_hda_get_sub_nodes(), was changed. As a result,
information for some converters was not stored to per_pin->mux_nids.
And this means some pins cannot be connected to all converters, and
application instead gets -EBUSY instead at open.

The assumption that converters are always before pins in the subnode
list, is not really a valid one. Fix the problem in hdmi_parse_codec()
by introducing separate loops for discovering converters and pins.

BugLink: https://github.com/thesofproject/linux/issues/1978
BugLink: https://github.com/thesofproject/linux/issues/2216
BugLink: https://github.com/thesofproject/linux/issues/2217Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20200703153818.2808592-1-kai.vehmanen@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

The stack object “info” in snd_opl3_ioctl() has a leaking problem.
It has 2 padding bytes which are not initialized and leaked via
“copy_to_user”.
Signed-off-by: xidongwang <wangxidong_97@163.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1594006058-30362-1-git-send-email-wangxidong_97@163.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

Removing IFX0102 from tpm_tis was not a right move because both tpm_tis
and tpm_infineon use the same device ID. Revert the commit and add a
remark about a bug caused by commit 93e1b7d4 ("[PATCH] tpm: add HID
module parameter").

Fixes: e918e570 ("tpm_tis: Remove the HID IFX0102")
Reported-by: Peter Huewe <peterhuewe@gmx.de>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

Pull kvm fixes from Paolo Bonzini:
 "Bugfixes and a one-liner patch to silence a sparse warning"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: arm64: Stop clobbering x0 for HVC_SOFT_RESTART
  KVM: arm64: PMU: Fix per-CPU access in preemptible context
  KVM: VMX: Use KVM_POSSIBLE_CR*_GUEST_BITS to initialize guest/host masks
  KVM: x86: Mark CR4.TSD as being possibly owned by the guest
  KVM: x86: Inject #GP if guest attempts to toggle CR4.LA57 in 64-bit mode
  kvm: use more precise cast and do not drop __user
  KVM: x86: bit 8 of non-leaf PDPEs is not reserved
  KVM: X86: Fix async pf caused null-ptr-deref
  KVM: arm64: vgic-v4: Plug race between non-residency and v4.1 doorbell
  KVM: arm64: pvtime: Ensure task delay accounting is enabled
  KVM: arm64: Fix kvm_reset_vcpu() return code being incorrect with SVE
  KVM: arm64: Annotate hyp NMI-related functions as __always_inline
  KVM: s390: reduce number of IO pins to 1

Pull s390 fixes from Heiko Carstens:

 - Initialize jump labels before early command line parsing in order to
   make init_on_alloc and init_on_free options work

 - Fix vfio-ccw build error due to missing include

 - Prevent callchain data collection with hardware sampling, since the
   callchains simply do not exist

 - Prevent multiple registrations of the same zPCI function

 - Update defconfigs

* tag 's390-5.8-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  vfio-ccw: Fix a build error due to missing include of linux/slab.h
  s390: update defconfigs
  s390/cpum_sf: prohibit callchain data collection
  s390/setup: init jump labels before command line parsing
  s390/maccess: add no DAT mode to kernel_write
  s390/pci: fix enabling a reserved PCI function

Merge tag 'kvmarm-fixes-5.8-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master

KVM/arm fixes for 5.8, take #3

- Disable preemption on context-switching PMU EL0 state happening
  on system register trap
- Don't clobber X0 when tearing down KVM via a soft reset (kexec)

Fixing the common case of:

  perf record
  perf report

And getting just the cycles events.

We now have a 'dummy' event to get perf metadata events that take place
while we synthesize metadata records for pre-existing processes by
traversing procfs, so we always have this extra 'dummy' evsel, but we
don't have to offer it as there will be no samples on it, remove this
distraction.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20200706115452.GA2772@redhat.com/Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The condition to add XMM registers was missing, the regs array needed to
be in the outer scope, and the size of the regs array was too small.

Fixes: 143d34a6 ("perf intel-pt: Add XMM registers to synthesized PEBS sample")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Luwei Kang <luwei.kang@intel.com>
Link: http://lore.kernel.org/lkml/20200630133935.11150-4-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

After recording PEBS-via-PT, perf script will not accept 'iregs' field e.g.

 # perf record -c 10000 -e '{intel_pt/branch=0/,branch-loads/aux-output/ppp}' -I -- ls -l
 ...
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.062 MB perf.data ]
 # ./perf script --itrace=eop -F+iregs
 Samples for 'dummy:u' event do not have IREGS attribute set. Cannot print 'iregs' field.

Fix by using allow_user_set, which is true when recording AUX area data.

Fixes: 9e64cefe ("perf intel-pt: Process options for PEBS event synthesis")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Luwei Kang <luwei.kang@intel.com>
Link: http://lore.kernel.org/lkml/20200630133935.11150-3-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

When recording PEBS-via-PT, the kernel will not accept the intel_pt
event with register sampling e.g.

 # perf record --kcore -c 10000 -e '{intel_pt/branch=0/,branch-loads/aux-output/ppp}' -I -- ls -l
 Error:
 intel_pt/branch=0/: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'

Fix by suppressing register sampling on the intel_pt evsel.

Committer notes:

Adrian informed that this is only available from Tremont onwards, so on
older processors the error continues the same as before.

Fixes: 9e64cefe ("perf intel-pt: Process options for PEBS event synthesis")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Luwei Kang <luwei.kang@intel.com>
Link: http://lore.kernel.org/lkml/20200630133935.11150-2-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The segmentation fault can be reproduced as following steps:

1) Executing perf report in tui.

2) Typing '/xxxxx' to filter the symbol to get nothing matched.

3) Pressing enter with no entry selected.

Then it will report a segmentation fault.

It is caused by the lack of check of browser->he_selection when
accessing it's member res_samples in perf_evsel__hists_browse().

These processes are meaningful for specified samples, so we can skip
these when nothing is selected.

Fixes: 4968ac8f ("perf report: Implement browsing of individual samples")
Signed-off-by: Wei Li <liwei391@huawei.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: http://lore.kernel.org/lkml/20200612094322.39565-1-liwei391@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

HVC_SOFT_RESTART is given values for x0-2 that it should installed
before exiting to the new address so should not set x0 to stub HVC
success or failure code.

Fixes: af42f204 ("arm64: hyp-stub: Zero x0 on successful stub handling")
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200706095259.1338221-1-ascull@google.com

Commit 07da1ffa ("KVM: arm64: Remove host_cpu_context
member from vcpu structure") has, by removing the host CPU
context pointer, exposed that kvm_vcpu_pmu_restore_guest
is called in preemptible contexts:

[  266.932442] BUG: using smp_processor_id() in preemptible [00000000] code: qemu-system-aar/779
[  266.939721] caller is debug_smp_processor_id+0x20/0x30
[  266.944157] CPU: 2 PID: 779 Comm: qemu-system-aar Tainted: G            E     5.8.0-rc3-00015-g8d4aa58b2fe3 #1374
[  266.954268] Hardware name: amlogic w400/w400, BIOS 2020.04 05/22/2020
[  266.960640] Call trace:
[  266.963064]  dump_backtrace+0x0/0x1e0
[  266.966679]  show_stack+0x20/0x30
[  266.969959]  dump_stack+0xe4/0x154
[  266.973338]  check_preemption_disabled+0xf8/0x108
[  266.977978]  debug_smp_processor_id+0x20/0x30
[  266.982307]  kvm_vcpu_pmu_restore_guest+0x2c/0x68
[  266.986949]  access_pmcr+0xf8/0x128
[  266.990399]  perform_access+0x8c/0x250
[  266.994108]  kvm_handle_sys_reg+0x10c/0x2f8
[  266.998247]  handle_exit+0x78/0x200
[  267.001697]  kvm_arch_vcpu_ioctl_run+0x2ac/0xab8

Note that the bug was always there, it is only the switch to
using percpu accessors that made it obvious.
The fix is to wrap these accesses in a preempt-disabled section,
so that we sample a coherent context on trap from the guest.

Fixes: 435e53fb ("arm64: KVM: Enable VHE support for :G/:H perf event modifiers")
Cc:: Andrew Murray <amurray@thegoodpenguin.co.uk>
Signed-off-by: Marc Zyngier <maz@kernel.org>

Using a mutex for "print this warning only once" is so overdesigned as
to be actively offensive to my sensitive stomach.

Just use "pr_info_once()" that already does this, although in a
(harmlessly) racy manner that can in theory cause the message to be
printed twice if more than one CPU races on that "is this the first
time" test.

[ If somebody really cares about that harmless data race (which sounds
  very unlikely indeed), that person can trivially fix printk_once() by
  using a simple atomic access, preferably with an optimistic non-atomic
  test first before even bothering to treat the pointless "make sure it
  is _really_ just once" case.

  A mutex is most definitely never the right primitive to use for
  something like this. ]

Yes, this is a small and meaningless detail in a code path that hardly
matters.  But let's keep some code quality standards here, and not
accept outrageously bad code.

Link: https://lore.kernel.org/lkml/CAHk-=wgV9toS7GU3KmNpj8hCS9SeF+A0voHS8F275_mgLhL4Lw@mail.gmail.com/
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull x86 fixes from Thomas Gleixner:
 "A series of fixes for x86:

   - Reset MXCSR in kernel_fpu_begin() to prevent using a stale user
     space value.

   - Prevent writing MSR_TEST_CTRL on CPUs which are not explicitly
     whitelisted for split lock detection. Some CPUs which do not
     support it crash even when the MSR is written to 0 which is the
     default value.

   - Fix the XEN PV fallout of the entry code rework

   - Fix the 32bit fallout of the entry code rework

   - Add more selftests to ensure that these entry problems don't come
     back.

   - Disable 16 bit segments on XEN PV. It's not supported because XEN
     PV does not implement ESPFIX64"

* tag 'x86-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ldt: Disable 16-bit segments on Xen PV
  x86/entry/32: Fix #MC and #DB wiring on x86_32
  x86/entry/xen: Route #DB correctly on Xen PV
  x86/entry, selftests: Further improve user entry sanity checks
  x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER
  selftests/x86: Consolidate and fix get/set_eflags() helpers
  selftests/x86/syscall_nt: Clear weird flags after each test
  selftests/x86/syscall_nt: Add more flag combinations
  x86/entry/64/compat: Fix Xen PV SYSENTER frame setup
  x86/entry: Move SYSENTER's regs->sp and regs->flags fixups into C
  x86/entry: Assert that syscalls are on the right stack
  x86/split_lock: Don't write MSR_TEST_CTRL on CPUs that aren't whitelisted
  x86/fpu: Reset MXCSR to default in kernel_fpu_begin()

Pull irq fixes from Thomas Gleixner:
 "A set of interrupt chip driver fixes:

   - Ensure the atomicity of affinity updates in the GIC driver

   - Don't try to sleep in atomic context when waiting for the GICv4.1
     to respond. Use polling instead.

   - Typo fixes in Kconfig and warnings"

* tag 'irq-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic: Atomically update affinity
  irqchip/riscv-intc: Fix a typo in a pr_warn()
  irqchip/gic-v4.1: Use readx_poll_timeout_atomic() to fix sleep in atomic
  irqchip/loongson-pci-msi: Fix a typo in Kconfig

Pull rcu fixlet from Thomas Gleixner:
 "A single fix for a printk format warning in RCU"

* tag 'core-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcuperf: Fix printk format warning

Merge tag 'kbuild-fixes-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes frin Masahiro Yamada:

 - fix various bugs in xconfig

 - fix some issues in cross-compilation using Clang

 - fix documentation

* tag 'kbuild-fixes-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  .gitignore: Do not track `defconfig` from `make savedefconfig`
  kbuild: make Clang build userprogs for target architecture
  kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang
  kconfig: qconf: parse newer types at debug info
  kconfig: qconf: navigate menus on hyperlinks
  kconfig: qconf: don't show goback button on splitMode
  kconfig: qconf: simplify the goBack() logic
  kconfig: qconf: re-implement setSelected()
  kconfig: qconf: make debug links work again
  kconfig: qconf: make search fully work again on split mode
  kconfig: qconf: cleanup includes
  docs: kbuild: fix ReST formatting
  gcc-plugins: fix gcc-plugins directory path in documentation

Pull SCSI fixes from James Bottomley:
 "Four small fixes in three drivers.

  The mptfusion one has actually caused user visible issues in certain
  kernel configurations"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: mptfusion: Don't use GFP_ATOMIC for larger DMA allocations
  scsi: libfc: Skip additional kref updating work event
  scsi: libfc: Handling of extra kref
  scsi: qla2xxx: Fix a condition in qla2x00_find_all_fabric_devs()

Pull block fixes from Jens Axboe:

 - NVMe fixes from Christoph:
    - Fix crash in multi-path disk add (Christoph)
    - Fix ignore of identify error (Sagi)

 - Fix a compiler complaint that a function should be static (Wei)

* tag 'block-5.8-2020-07-05' of git://git.kernel.dk/linux-block:
  block: make function __bio_integrity_free() static
  nvme: fix a crash in nvme_mpath_add_disk
  nvme: fix identify error status silent ignore

Pull io_uring fix from Jens Axboe:
 "Andres reported a regression with the fix that was merged earlier this
  week, where his setup of using signals to interrupt io_uring CQ waits
  no longer worked correctly.

  Fix this, and also limit our use of TWA_SIGNAL to the case where we
  need it, and continue using TWA_RESUME for task_work as before.

  Since the original is marked for 5.7 stable, let's flush this one out
  early"

* tag 'io_uring-5.8-2020-07-05' of git://git.kernel.dk/linux-block:
  io_uring: fix regression with always ignoring signals in io_cqring_wait()

Pull i2c fixes from Wolfram Sang:
 "The usual driver fixes and documentation updates"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: mlxcpld: check correct size of maximum RECV_LEN packet
  i2c: add Kconfig help text for slave mode
  i2c: slave-eeprom: update documentation
  i2c: eg20t: Load module automatically if ID matches
  i2c: designware: platdrv: Set class based on DMI
  i2c: algo-pca: Add 0x78 as SCL stuck low status for PCA9665