linux-stable.git/arch/x86/kernel/cpu/mcheck, branch linux-4.3.y

x86/mce: Ensure offline CPUs don't participate in rendezvous process

2016-01-31T19:25:43+00:00

commit d90167a941f62860f35eb960e1012aa2d30e7e94 upstream.

Intel's MCA implementation broadcasts MCEs to all CPUs on the
node. This poses a problem for offlined CPUs which cannot
participate in the rendezvous process:

  Kernel panic - not syncing: Timeout: Not all CPUs entered broadcast exception handler
  Kernel Offset: disabled
  Rebooting in 100 seconds..

More specifically, Linux does a soft offline of a CPU when
writing a 0 to /sys/devices/system/cpu/cpuX/online, which
doesn't prevent the #MC exception from being broadcasted to that
CPU.

Ensure that offline CPUs don't participate in the MCE rendezvous
and clear the RIP valid status bit so that a second MCE won't
cause a shutdown.

Without the patch, mce_start() will increment mce_callin and
wait for all CPUs. Offlined CPUs should avoid participating in
the rendezvous process altogether.

Signed-off-by: Ashok Raj 
[ Massage commit message. ]
Signed-off-by: Borislav Petkov 
Reviewed-by: Tony Luck 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-edac 
Link: http://lkml.kernel.org/r/1449742346-21470-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-09-01T15:40:25+00:00

Pull x86 asm changes from Ingo Molnar:
 "The biggest changes in this cycle were:

   - Revamp, simplify (and in some cases fix) Time Stamp Counter (TSC)
     primitives.  (Andy Lutomirski)

   - Add new, comprehensible entry and exit handlers written in C.
     (Andy Lutomirski)

   - vm86 mode cleanups and fixes.  (Brian Gerst)

   - 32-bit compat code cleanups.  (Brian Gerst)

  The amount of simplification in low level assembly code is already
  palpable:

     arch/x86/entry/entry_32.S                          | 130 +----
     arch/x86/entry/entry_64.S                          | 197 ++-----

  but more simplifications are planned.

  There's also the usual laudry mix of low level changes - see the
  changelog for details"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (83 commits)
  x86/asm: Drop repeated macro of X86_EFLAGS_AC definition
  x86/asm/msr: Make wrmsrl() a function
  x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer
  x86/asm: Add MONITORX/MWAITX instruction support
  x86/traps: Weaken context tracking entry assertions
  x86/asm/tsc: Add rdtscll() merge helper
  selftests/x86: Add syscall_nt selftest
  selftests/x86: Disable sigreturn_64
  x86/vdso: Emit a GNU hash
  x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks
  x86/entry/32: Migrate to C exit path
  x86/entry/32: Remove 32-bit syscall audit optimizations
  x86/vm86: Rename vm86->v86flags and v86mask
  x86/vm86: Rename vm86->vm86_info to user_vm86
  x86/vm86: Clean up vm86.h includes
  x86/vm86: Move the vm86 IRQ definitions to vm86.h
  x86/vm86: Use the normal pt_regs area for vm86
  x86/vm86: Eliminate 'struct kernel_vm86_struct'
  x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'
  x86/vm86: Move vm86 fields out of 'thread_struct'
  ...

Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-09-01T03:20:30+00:00

Pull RAS updates from Ingo Molnar:
 "MCE handling updates, but also some generic drivers/edac/ changes to
  better organize the Kconfig space"

* 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ras: Move AMD MCE injector to arch/x86/ras/
  x86/mce: Add a wrapper around mce_log() for injection
  x86/mce: Rename rcu_dereference_check_mce() to mce_log_get_idx_check()
  RAS: Add a menuconfig option with descriptive text
  x86/mce: Reenable CMCI banks when swiching back to interrupt mode
  x86/mce: Clear Local MCE opt-in before kexec
  x86/mce: Remove unused function declarations
  x86/mce: Kill drain_mcelog_buffer()
  x86/mce: Avoid potential deadlock due to printk() in MCE context
  x86/mce: Remove the MCE ring for Action Optional errors
  x86/mce: Don't use percpu workqueues
  x86/mce: Provide a lockless memory pool to save error records
  x86/mce: Reuse one of the u16 padding fields in 'struct mce'

x86/mce: Add a wrapper around mce_log() for injection

2015-08-13T08:12:53+00:00

Will be used by an injector module in a following patch.

Additionally, add a missing module export reported by 0-DAY
kernel test.

Reported-by: kbuild test robot 
Signed-off-by: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Link: http://lkml.kernel.org/r/1439396985-12812-13-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

x86/mce: Rename rcu_dereference_check_mce() to mce_log_get_idx_check()

2015-08-13T08:12:53+00:00

The "rcu_" prefix misleads for it being a proper RCU interface
which is not. It basically checks whether we're preemptible or
holding the chrdev_read mutex.

Rename it accordingly.

Signed-off-by: Borislav Petkov 
Acked-by: Paul E. McKenney 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Link: http://lkml.kernel.org/r/1439396985-12812-12-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

x86/mce: Reenable CMCI banks when swiching back to interrupt mode

2015-08-13T08:12:52+00:00

Zhang Liguang reported the following issue:

1) System detects a CMCI storm on the current CPU.

2) Kernel disables the CMCI interrupt on banks owned by the
   current CPU and switches to poll mode

3) After the CMCI storm subsides, kernel switches back to
   interrupt mode

4) We expect the system to reenable the CMCI interrupt on banks
   owned by the current CPU

   mce_intel_adjust_timer
   |-> cmci_reenable
       |-> cmci_discover     # owned banks are ignored here

  static void cmci_discover(int banks)
	...
	for (i = 0; i < banks; i++) {
		...
		if (test_bit(i, owned))	# ownd banks is ignore here
			continue;

So convert cmci_storm_disable_banks() to
cmci_toggle_interrupt_mode() which controls whether to enable or
disable CMCI interrupts with its argument.

NB: We cannot clear the owned bit because the banks won't be
polled, otherwise. See:

  27f6c573e0f7 ("x86, CMCI: Add proper detection of end of CMCI storms")

for more info.

Reported-by: Zhang Liguang 
Signed-off-by: Xie XiuQi 
Signed-off-by: Borislav Petkov 
Cc:  # v3.15+
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: huawei.libin@huawei.com
Cc: linux-edac 
Cc: rui.xiang@huawei.com
Link: http://lkml.kernel.org/r/1439396985-12812-10-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

x86/mce: Clear Local MCE opt-in before kexec

2015-08-13T08:12:52+00:00

kexec could boot a kernel that could be legacy with no knowledge
of LMCE. Hence we should make sure we clear LMCE optin before
kexec reboot.

Signed-off-by: Ashok Raj 
Signed-off-by: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Aravind Gopalakrishnan 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: linux-edac 
Link: http://lkml.kernel.org/r/1439396985-12812-9-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

x86/mce: Kill drain_mcelog_buffer()

2015-08-13T08:12:52+00:00

This used to flush out MCEs logged during early boot and which
were in the MCA registers from a previous system run. No need
for that now, since we've moved to a genpool.

Suggested-by: Tony Luck 
Signed-off-by: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1439396985-12812-7-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

x86/mce: Avoid potential deadlock due to printk() in MCE context

2015-08-13T08:12:51+00:00

Printing in MCE context is a no-no, currently, as printk() is
not NMI-safe. If some of the notifiers on the MCE chain call do
so, we may deadlock. In order to avoid that, delay printk() to
process context where it is safe.

Reported-by: Xie XiuQi 
Signed-off-by: Chen, Gong 
[ Fold in subsequent patch from Boris for early boot logging. ]
Signed-off-by: Tony Luck 
[ Kick irq_work in mce_log() directly. ]
Signed-off-by: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1439396985-12812-6-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

x86/mce: Remove the MCE ring for Action Optional errors

2015-08-13T08:12:51+00:00

Use unified genpool to save Action Optional error events and put
Action Optional error handling in the same notification chain as
MCE error decoding.

Signed-off-by: Chen, Gong 
[ Fold in subsequent patch from Boris for early boot logging. ]
Signed-off-by: Tony Luck 
[ Correct a lot. ]
Signed-off-by: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1439396985-12812-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar