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  1. 16 Feb, 2018 5 commits
    • Lukas Wunner's avatar
      drm/amdgpu: Fix deadlock on runtime suspend · aa0aad57
      Lukas Wunner authored 
      amdgpu's ->runtime_suspend hook calls drm_kms_helper_poll_disable(),
which waits for the output poll worker to finish if it's running.

The output poll worker meanwhile calls pm_runtime_get_sync() in
amdgpu's ->detect hooks, which waits for the ongoing suspend to finish,
causing a deadlock.

Fix by not acquiring a runtime PM ref if the ->detect hooks are called
in the output poll worker's context.  This is safe because the poll
worker is only enabled while runtime active and we know that
->runtime_suspend waits for it to finish.

Fixes: d38ceaf9 ("drm/amdgpu: add core driver (v4)")
Cc: stable@vger.kernel.org # v4.2+: 27d4ee03: workqueue: Allow retrieval of current task's work struct
Cc: stable@vger.kernel.org # v4.2+: 25c058cc: drm: Allow determining if current task is output poll worker
Cc: Alex Deucher <alexander.deucher@amd.com>
Tested-by: default avatarMike Lothian <mike@fireburn.co.uk>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/4c9bf72aacae1eef062bd134cd112e0770a7f121.1518338789.git.lukas@wunner.de
      aa0aad57
    • Lukas Wunner's avatar
      drm/radeon: Fix deadlock on runtime suspend · 15734fef
      Lukas Wunner authored 
      radeon's ->runtime_suspend hook calls drm_kms_helper_poll_disable(),
which waits for the output poll worker to finish if it's running.

The output poll worker meanwhile calls pm_runtime_get_sync() in
radeon's ->detect hooks, which waits for the ongoing suspend to finish,
causing a deadlock.

Fix by not acquiring a runtime PM ref if the ->detect hooks are called
in the output poll worker's context.  This is safe because the poll
worker is only enabled while runtime active and we know that
->runtime_suspend waits for it to finish.

Stack trace for posterity:

  INFO: task kworker/0:3:31847 blocked for more than 120 seconds
  Workqueue: events output_poll_execute [drm_kms_helper]
  Call Trace:
   schedule+0x3c/0x90
   rpm_resume+0x1e2/0x690
   __pm_runtime_resume+0x3f/0x60
   radeon_lvds_detect+0x39/0xf0 [radeon]
   output_poll_execute+0xda/0x1e0 [drm_kms_helper]
   process_one_work+0x14b/0x440
   worker_thread+0x48/0x4a0

  INFO: task kworker/2:0:10493 blocked for more than 120 seconds.
  Workqueue: pm pm_runtime_work
  Call Trace:
   schedule+0x3c/0x90
   schedule_timeout+0x1b3/0x240
   wait_for_common+0xc2/0x180
   wait_for_completion+0x1d/0x20
   flush_work+0xfc/0x1a0
   __cancel_work_timer+0xa5/0x1d0
   cancel_delayed_work_sync+0x13/0x20
   drm_kms_helper_poll_disable+0x1f/0x30 [drm_kms_helper]
   radeon_pmops_runtime_suspend+0x3d/0xa0 [radeon]
   pci_pm_runtime_suspend+0x61/0x1a0
   vga_switcheroo_runtime_suspend+0x21/0x70
   __rpm_callback+0x32/0x70
   rpm_callback+0x24/0x80
   rpm_suspend+0x12b/0x640
   pm_runtime_work+0x6f/0xb0
   process_one_work+0x14b/0x440
   worker_thread+0x48/0x4a0

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94147
Fixes: 10ebc0bc ("drm/radeon: add runtime PM support (v2)")
Cc: stable@vger.kernel.org # v3.13+: 27d4ee03: workqueue: Allow retrieval of current task's work struct
Cc: stable@vger.kernel.org # v3.13+: 25c058cc: drm: Allow determining if current task is output poll worker
Cc: Ismo Toijala <ismo.toijala@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/64ea02c44f91dda19bc563902b97bbc699040392.1518338789.git.lukas@wunner.de
      15734fef
    • Lukas Wunner's avatar
      drm/nouveau: Fix deadlock on runtime suspend · d61a5c10
      Lukas Wunner authored 
      nouveau's ->runtime_suspend hook calls drm_kms_helper_poll_disable(),
which waits for the output poll worker to finish if it's running.

The output poll worker meanwhile calls pm_runtime_get_sync() in
nouveau_connector_detect() which waits for the ongoing suspend to finish,
causing a deadlock.

Fix by not acquiring a runtime PM ref if nouveau_connector_detect() is
called in the output poll worker's context.  This is safe because
the poll worker is only enabled while runtime active and we know that
->runtime_suspend waits for it to finish.

Other contexts calling nouveau_connector_detect() do require a runtime
PM ref, these comprise:

  status_store() drm sysfs interface
  ->fill_modes drm callback
  drm_fb_helper_probe_connector_modes()
  drm_mode_getconnector()
  nouveau_connector_hotplug()
  nouveau_display_hpd_work()
  nv17_tv_set_property()

Stack trace for posterity:

  INFO: task kworker/0:1:58 blocked for more than 120 seconds.
  Workqueue: events output_poll_execute [drm_kms_helper]
  Call Trace:
   schedule+0x28/0x80
   rpm_resume+0x107/0x6e0
   __pm_runtime_resume+0x47/0x70
   nouveau_connector_detect+0x7e/0x4a0 [nouveau]
   nouveau_connector_detect_lvds+0x132/0x180 [nouveau]
   drm_helper_probe_detect_ctx+0x85/0xd0 [drm_kms_helper]
   output_poll_execute+0x11e/0x1c0 [drm_kms_helper]
   process_one_work+0x184/0x380
   worker_thread+0x2e/0x390

  INFO: task kworker/0:2:252 blocked for more than 120 seconds.
  Workqueue: pm pm_runtime_work
  Call Trace:
   schedule+0x28/0x80
   schedule_timeout+0x1e3/0x370
   wait_for_completion+0x123/0x190
   flush_work+0x142/0x1c0
   nouveau_pmops_runtime_suspend+0x7e/0xd0 [nouveau]
   pci_pm_runtime_suspend+0x5c/0x180
   vga_switcheroo_runtime_suspend+0x1e/0xa0
   __rpm_callback+0xc1/0x200
   rpm_callback+0x1f/0x70
   rpm_suspend+0x13c/0x640
   pm_runtime_work+0x6e/0x90
   process_one_work+0x184/0x380
   worker_thread+0x2e/0x390

Bugzilla: https://bugs.archlinux.org/task/53497
Bugzilla: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=870523
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70388#c33
Fixes: 5addcf0a ("nouveau: add runtime PM support (v0.9)")
Cc: stable@vger.kernel.org # v3.12+: 27d4ee03: workqueue: Allow retrieval of current task's work struct
Cc: stable@vger.kernel.org # v3.12+: 25c058cc: drm: Allow determining if current task is output poll worker
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/b7d2cbb609a80f59ccabfdf479b9d5907c603ea1.1518338789.git.lukas@wunner.de
      d61a5c10
    • Lukas Wunner's avatar
      drm: Allow determining if current task is output poll worker · 25c058cc
      Lukas Wunner authored 
      Introduce a helper to determine if the current task is an output poll
worker.

This allows us to fix a long-standing deadlock in several DRM drivers
wherein the ->runtime_suspend callback waits for the output poll worker
to finish and the worker in turn calls a ->detect callback which waits
for runtime suspend to finish.  The ->detect callback is invoked from
multiple call sites and waiting for runtime suspend to finish is the
correct thing to do except if it's executing in the context of the
worker.

v2: Expand kerneldoc to specifically mention deadlock between
    output poll worker and autosuspend worker as use case. (Lyude)

Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/3549ce32e7f1467102e70d3e9cbf70c46bfe108e.1518593424.git.lukas@wunner.de
      25c058cc
    • Lukas Wunner's avatar
      workqueue: Allow retrieval of current task's work struct · 27d4ee03
      Lukas Wunner authored 
      Introduce a helper to retrieve the current task's work struct if it is
a workqueue worker.

This allows us to fix a long-standing deadlock in several DRM drivers
wherein the ->runtime_suspend callback waits for a specific worker to
finish and that worker in turn calls a function which waits for runtime
suspend to finish.  That function is invoked from multiple call sites
and waiting for runtime suspend to finish is the correct thing to do
except if it's executing in the context of the worker.

Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/2d8f603074131eb87e588d2b803a71765bd3a2fd.1518338788.git.lukas@wunner.de
      27d4ee03
  3. 01 Feb, 2018 1 commit
  5. 31 Jan, 2018 1 commit
  7. 18 Jan, 2018 4 commits
  9. 17 Jan, 2018 2 commits
  11. 14 Jan, 2018 9 commits
    • Linus Torvalds's avatar
      Linux 4.15-rc8 · a8750ddc
      Linus Torvalds authored
      a8750ddc
    • Linus Torvalds's avatar
      Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · aaae98a8
      Linus Torvalds authored 
      Pull x86 fixlet from Thomas Gleixner.

Remove a warning about lack of compiler support for retpoline that most
people can't do anything about, so it just annoys them needlessly.

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/retpoline: Remove compile time warning
      aaae98a8
    • Linus Torvalds's avatar
      Merge tag 'powerpc-4.15-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux · 6bb82119
      Linus Torvalds authored 
      Pull powerpc fixes from Michael Ellerman:
 "One fix for an oops at boot if we take a hotplug interrupt before we
  are ready to handle it.

  The bulk is patches to implement mitigation for Meltdown, see the
  change logs for more details.

  Thanks to: Nicholas Piggin, Michael Neuling, Oliver O'Halloran, Jon
  Masters, Jose Ricardo Ziviani, David Gibson"

* tag 'powerpc-4.15-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/powernv: Check device-tree for RFI flush settings
  powerpc/pseries: Query hypervisor for RFI flush settings
  powerpc/64s: Support disabling RFI flush with no_rfi_flush and nopti
  powerpc/64s: Add support for RFI flush of L1-D cache
  powerpc/64s: Convert slb_miss_common to use RFI_TO_USER/KERNEL
  powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL
  powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL
  powerpc/64s: Simple RFI macro conversions
  powerpc/64: Add macros for annotating the destination of rfid/hrfid
  powerpc/pseries: Add H_GET_CPU_CHARACTERISTICS flags & wrapper
  powerpc/pseries: Make RAS IRQ explicitly dependent on DLPAR WQ
      6bb82119
    • Thomas Gleixner's avatar
      x86/retpoline: Remove compile time warning · b8b9ce4b
      Thomas Gleixner authored 
      Remove the compile time warning when CONFIG_RETPOLINE=y and the compiler
does not have retpoline support. Linus rationale for this is:

  It's wrong because it will just make people turn off RETPOLINE, and the
  asm updates - and return stack clearing - that are independent of the
  compiler are likely the most important parts because they are likely the
  ones easiest to target.

  And it's annoying because most people won't be able to do anything about
  it. The number of people building their own compiler? Very small. So if
  their distro hasn't got a compiler yet (and pretty much nobody does), the
  warning is just annoying crap.

  It is already properly reported as part of the sysfs interface. The
  compile-time warning only encourages bad things.

Fixes: 76b04384 ("x86/retpoline: Add initial retpoline support")
Requested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: thomas.lendacky@amd.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Link: https://lkml.kernel.org/r/CA+55aFzWgquv4i6Mab6bASqYXg3ErV3XDFEYf=GEcCDQg5uAtw@mail.gmail.com
      b8b9ce4b
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.dk/linux-block · 9443c168
      Linus Torvalds authored 
      Pull NVMe fix from Jens Axboe:
 "Just a single fix for nvme over fabrics that should go into 4.15"

* 'for-linus' of git://git.kernel.dk/linux-block:
  nvme-fabrics: initialize default host->id in nvmf_host_default()
      9443c168
    • Linus Torvalds's avatar
      Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 40548c6b
      Linus Torvalds authored 
      Pull x86 pti updates from Thomas Gleixner:
 "This contains:

   - a PTI bugfix to avoid setting reserved CR3 bits when PCID is
     disabled. This seems to cause issues on a virtual machine at least
     and is incorrect according to the AMD manual.

   - a PTI bugfix which disables the perf BTS facility if PTI is
     enabled. The BTS AUX buffer is not globally visible and causes the
     CPU to fault when the mapping disappears on switching CR3 to user
     space. A full fix which restores BTS on PTI is non trivial and will
     be worked on.

   - PTI bugfixes for EFI and trusted boot which make sure that the user
     space visible page table entries have the NX bit cleared

   - removal of dead code in the PTI pagetable setup functions

   - add PTI documentation

   - add a selftest for vsyscall to verify that the kernel actually
     implements what it advertises.

   - a sysfs interface to expose vulnerability and mitigation
     information so there is a coherent way for users to retrieve the
     status.

   - the initial spectre_v2 mitigations, aka retpoline:

      + The necessary ASM thunk and compiler support

      + The ASM variants of retpoline and the conversion of affected ASM
        code

      + Make LFENCE serializing on AMD so it can be used as speculation
        trap

      + The RSB fill after vmexit

   - initial objtool support for retpoline

  As I said in the status mail this is the most of the set of patches
  which should go into 4.15 except two straight forward patches still on
  hold:

   - the retpoline add on of LFENCE which waits for ACKs

   - the RSB fill after context switch

  Both should be ready to go early next week and with that we'll have
  covered the major holes of spectre_v2 and go back to normality"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits)
  x86,perf: Disable intel_bts when PTI
  security/Kconfig: Correct the Documentation reference for PTI
  x86/pti: Fix !PCID and sanitize defines
  selftests/x86: Add test_vsyscall
  x86/retpoline: Fill return stack buffer on vmexit
  x86/retpoline/irq32: Convert assembler indirect jumps
  x86/retpoline/checksum32: Convert assembler indirect jumps
  x86/retpoline/xen: Convert Xen hypercall indirect jumps
  x86/retpoline/hyperv: Convert assembler indirect jumps
  x86/retpoline/ftrace: Convert ftrace assembler indirect jumps
  x86/retpoline/entry: Convert entry assembler indirect jumps
  x86/retpoline/crypto: Convert crypto assembler indirect jumps
  x86/spectre: Add boot time option to select Spectre v2 mitigation
  x86/retpoline: Add initial retpoline support
  objtool: Allow alternatives to be ignored
  objtool: Detect jumps to retpoline thunks
  x86/pti: Make unpoison of pgd for trusted boot work for real
  x86/alternatives: Fix optimize_nops() checking
  sysfs/cpu: Fix typos in vulnerability documentation
  x86/cpu/AMD: Use LFENCE_RDTSC in preference to MFENCE_RDTSC
  ...
      40548c6b
    • Peter Zijlstra's avatar
      x86,perf: Disable intel_bts when PTI · 99a9dc98
      Peter Zijlstra authored 
      The intel_bts driver does not use the 'normal' BTS buffer which is exposed
through the cpu_entry_area but instead uses the memory allocated for the
perf AUX buffer.

This obviously comes apart when using PTI because then the kernel mapping;
which includes that AUX buffer memory; disappears. Fixing this requires to
expose a mapping which is visible in all context and that's not trivial.

As a quick fix disable this driver when PTI is enabled to prevent
malfunction.

Fixes: 385ce0ea ("x86/mm/pti: Add Kconfig")
Reported-by: default avatarVince Weaver <vincent.weaver@maine.edu>
Reported-by: default avatarRobert Święcki <robert@swiecki.net>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: greg@kroah.com
Cc: hughd@google.com
Cc: luto@amacapital.net
Cc: Vince Weaver <vince@deater.net>
Cc: torvalds@linux-foundation.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180114102713.GB6166@worktop.programming.kicks-ass.net
      99a9dc98
    • W. Trevor King's avatar
      security/Kconfig: Correct the Documentation reference for PTI · a237f762
      W. Trevor King authored 
      When the config option for PTI was added a reference to documentation was
added as well. But the documentation did not exist at that point. The final
documentation has a different file name.

Fix it up to point to the proper file.

Fixes: 385ce0ea ("x86/mm/pti: Add Kconfig")
Signed-off-by: default avatarW. Trevor King <wking@tremily.us>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-security-module@vger.kernel.org
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/3009cc8ccbddcd897ec1e0cb6dda524929de0d14.1515799398.git.wking@tremily.us
      a237f762
    • Thomas Gleixner's avatar
      x86/pti: Fix !PCID and sanitize defines · f10ee3dc
      Thomas Gleixner authored 
      The switch to the user space page tables in the low level ASM code sets
unconditionally bit 12 and bit 11 of CR3. Bit 12 is switching the base
address of the page directory to the user part, bit 11 is switching the
PCID to the PCID associated with the user page tables.

This fails on a machine which lacks PCID support because bit 11 is set in
CR3. Bit 11 is reserved when PCID is inactive.

While the Intel SDM claims that the reserved bits are ignored when PCID is
disabled, the AMD APM states that they should be cleared.

This went unnoticed as the AMD APM was not checked when the code was
developed and reviewed and test systems with Intel CPUs never failed to
boot. The report is against a Centos 6 host where the guest fails to boot,
so it's not yet clear whether this is a virt issue or can happen on real
hardware too, but thats irrelevant as the AMD APM clearly ask for clearing
the reserved bits.

Make sure that on non PCID machines bit 11 is not set by the page table
switching code.

Andy suggested to rename the related bits and masks so they are clearly
describing what they should be used for, which is done as well for clarity.

That split could have been done with alternatives but the macro hell is
horrible and ugly. This can be done on top if someone cares to remove the
extra orq. For now it's a straight forward fix.

Fixes: 6fd166aa ("x86/mm: Use/Fix PCID to optimize user/kernel switches")
Reported-by: default avatarLaura Abbott <labbott@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable <stable@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801140009150.2371@nanos
      f10ee3dc
  13. 13 Jan, 2018 13 commits
  15. 12 Jan, 2018 5 commits
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