kernel.git/arch/x86/kernel/cpu, branch linux-3.15.y

perf/x86/intel: ignore CondChgd bit to avoid false NMI handling

2014-07-28T15:08:26Z

commit b292d7a10487aee6e74b1c18b8d95b92f40d4a4f upstream. Currently, any NMI is falsely handled by a NMI handler of NMI watchdog if CondChgd bit in MSR_CORE_PERF_GLOBAL_STATUS MSR is set. For example, we use external NMI to make system panic to get crash dump, but in this case, the external NMI is falsely handled do to the issue. This commit deals with the issue simply by ignoring CondChgd bit. Here is explanation in detail. On x86 NMI watchdog uses performance monitoring feature to periodically signal NMI each time performance counter gets overflowed. intel_pmu_handle_irq() is called as a NMI_LOCAL handler from a NMI handler of NMI watchdog, perf_event_nmi_handler(). It identifies an owner of a given NMI by looking at overflow status bits in MSR_CORE_PERF_GLOBAL_STATUS MSR. If some of the bits are set, then it handles the given NMI as its own NMI. The problem is that the intel_pmu_handle_irq() doesn't distinguish CondChgd bit from other bits. Unlike the other status bits, CondChgd bit doesn't represent overflow status for performance counters. Thus, CondChgd bit cannot be thought of as a mark indicating a given NMI is NMI watchdog's. As a result, if CondChgd bit is set, any NMI is falsely handled by the NMI handler of NMI watchdog. Also, if type of the falsely handled NMI is either NMI_UNKNOWN, NMI_SERR or NMI_IO_CHECK, the corresponding action is never performed until CondChgd bit is cleared. I noticed this behavior on systems with Ivy Bridge processors: Intel Xeon CPU E5-2630 v2 and Intel Xeon CPU E7-8890 v2. On both systems, CondChgd bit in MSR_CORE_PERF_GLOBAL_STATUS MSR has already been set in the beginning at boot. Then the CondChgd bit is immediately cleared by next wrmsr to MSR_CORE_PERF_GLOBAL_CTRL MSR and appears to remain 0. On the other hand, on older processors such as Nehalem, Xeon E7540, CondChgd bit is not set in the beginning at boot. I'm not sure about exact behavior of CondChgd bit, in particular when this bit is set. Although I read Intel System Programmer's Manual to figure out that, the descriptions I found are: In 18.9.1: "The MSR_PERF_GLOBAL_STATUS MSR also provides a ¡sticky bit¢ to indicate changes to the state of performancmonitoring hardware" In Table 35-2 IA-32 Architectural MSRs 63 CondChg: status bits of this register has changed. These are different from the bahviour I see on the actual system as I explained above. At least, I think ignoring CondChgd bit should be enough for NMI watchdog perspective. Signed-off-by: HATAYAMA Daisuke Acked-by: Don Zickus Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20140625.103503.409316067.d.hatayama@jp.fujitsu.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

Revert "x86/smpboot: Initialize secondary CPU only if master CPU will wait for it"

2014-06-08T17:09:49Z

This reverts commit 3e1a878b7ccdb31da6d9d2b855c72ad87afeba3f. It came in very late, and already has one reported failure: Sitsofe reports that the current tree fails to boot on his EeePC, and bisected it down to this. Rather than waste time trying to figure out what's wrong, just revert it. Reported-by: Sitsofe Wheeler Cc: Igor Mammedov Cc: Toshi Kani Cc: Thomas Gleixner Acked-by: Ingo Molnar Signed-off-by: Linus Torvalds

x86/smpboot: Initialize secondary CPU only if master CPU will wait for it

2014-06-05T14:33:08Z

Hang is observed on virtual machines during CPU hotplug, especially in big guests with many CPUs. (It reproducible more often if host is over-committed). It happens because master CPU gives up waiting on secondary CPU and allows it to run wild. As result AP causes locking or crashing system. For example as described here: https://lkml.org/lkml/2014/3/6/257 If master CPU have sent STARTUP IPI successfully, and AP signalled to master CPU that it's ready to start initialization, make master CPU wait indefinitely till AP is onlined. To ensure that AP won't ever run wild, make it wait at early startup till master CPU confirms its intention to wait for AP. If AP doesn't respond in 10 seconds, the master CPU will timeout and cancel AP onlining. Signed-off-by: Igor Mammedov Acked-by: Toshi Kani Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1401975765-22328-4-git-send-email-imammedo@redhat.com Signed-off-by: Ingo Molnar

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

2014-05-23T17:02:34Z

Pull perf fixes from Ingo Molnar: "The biggest changes are fixes for races that kept triggering Trinity crashes, plus liblockdep build fixes and smaller misc fixes. The liblockdep bits in perf/urgent are a pull mistake - they should have been in locking/urgent - but by the time I noticed other commits were added and testing was done :-/ Sorry about that" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Fix a race between ring_buffer_detach() and ring_buffer_attach() perf: Prevent false warning in perf_swevent_add perf: Limit perf_event_attr::sample_period to 63 bits tools/liblockdep: Remove all build files when doing make clean tools/liblockdep: Build liblockdep from tools/Makefile perf/x86/intel: Fix Silvermont's event constraints perf: Fix perf_event_init_context() perf: Fix race in removing an event

x86, rdrand: When nordrand is specified, disable RDSEED as well

2014-05-12T03:25:20Z

One can logically expect that when the user has specified "nordrand", the user doesn't want any use of the CPU random number generator, neither RDRAND nor RDSEED, so disable both. Reported-by: Stephan Mueller Cc: Theodore Ts'o Link: http://lkml.kernel.org/r/21542339.0lFnPSyGRS@myon.chronox.de Signed-off-by: H. Peter Anvin

perf/x86/intel: Fix Silvermont's event constraints

2014-05-07T09:33:16Z

Event 0x013c is not the same as fixed counter2, remove it from Silvermont's event constraints. Signed-off-by: Yan, Zheng Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1398755081-12471-1-git-send-email-zheng.z.yan@intel.com Signed-off-by: Ingo Molnar

asmlinkage, x86: Add explicit __visible to arch/x86/*

2014-05-05T23:07:44Z

As requested by Linus add explicit __visible to the asmlinkage users. This marks all functions visible to assembler. Tree sweep for arch/x86/* Signed-off-by: Andi Kleen Link: http://lkml.kernel.org/r/1398984278-29319-3-git-send-email-andi@firstfloor.org Signed-off-by: H. Peter Anvin

perf/x86: Fix RAPL rdmsrl_safe() usage

2014-04-24T06:12:41Z

This patch fixes a bug introduced by: 24223657806a ("perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU") The rdmsrl_safe() function returns 0 on success. The current code was failing to detect the RAPL PMU on real hardware (missing /sys/devices/power) because the return value of rdmsrl_safe() was misinterpreted. Signed-off-by: Stephane Eranian Acked-by: Borislav Petkov Acked-by: Venkatesh Srinivas Cc: peterz@infradead.org Cc: zheng.z.yan@intel.com Link: http://lkml.kernel.org/r/20140423170418.GA12767@quad Signed-off-by: Ingo Molnar

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

2014-04-19T17:41:43Z

Pull x86 fix from Ingo Molnar: "This fixes the preemption-count imbalance crash reported by Owen Kibel" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mce: Fix CMCI preemption bugs

perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU

2014-04-18T10:14:26Z

CPUs which should support the RAPL counters according to Family/Model/Stepping may still issue #GP when attempting to access the RAPL MSRs. This may happen when Linux is running under KVM and we are passing-through host F/M/S data, for example. Use rdmsrl_safe to first access the RAPL_POWER_UNIT MSR; if this fails, do not attempt to use this PMU. Signed-off-by: Venkatesh Srinivas Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1394739386-22260-1-git-send-email-venkateshs@google.com Cc: zheng.z.yan@intel.com Cc: eranian@google.com Cc: ak@linux.intel.com Cc: linux-kernel@vger.kernel.org [ The patch also silently fixes another bug: rapl_pmu_init() didn't handle the memory alloc failure case previously. ] Signed-off-by: Ingo Molnar