+++ /dev/null
-From bfa8b866e3bce1f3c80a52fdd3a38431692e0fab Mon Sep 17 00:00:00 2001
-From: Sasha Levin <sashal@kernel.org>
-Date: Mon, 19 Aug 2019 19:13:31 -0400
-Subject: perf/x86/intel: Restrict period on Nehalem
-
-From: Josh Hunt <johunt@akamai.com>
-
-[ Upstream commit 44d3bbb6f5e501b873218142fe08cdf62a4ac1f3 ]
-
-We see our Nehalem machines reporting 'perfevents: irq loop stuck!' in
-some cases when using perf:
-
-perfevents: irq loop stuck!
-WARNING: CPU: 0 PID: 3485 at arch/x86/events/intel/core.c:2282 intel_pmu_handle_irq+0x37b/0x530
-...
-RIP: 0010:intel_pmu_handle_irq+0x37b/0x530
-...
-Call Trace:
-<NMI>
-? perf_event_nmi_handler+0x2e/0x50
-? intel_pmu_save_and_restart+0x50/0x50
-perf_event_nmi_handler+0x2e/0x50
-nmi_handle+0x6e/0x120
-default_do_nmi+0x3e/0x100
-do_nmi+0x102/0x160
-end_repeat_nmi+0x16/0x50
-...
-? native_write_msr+0x6/0x20
-? native_write_msr+0x6/0x20
-</NMI>
-intel_pmu_enable_event+0x1ce/0x1f0
-x86_pmu_start+0x78/0xa0
-x86_pmu_enable+0x252/0x310
-__perf_event_task_sched_in+0x181/0x190
-? __switch_to_asm+0x41/0x70
-? __switch_to_asm+0x35/0x70
-? __switch_to_asm+0x41/0x70
-? __switch_to_asm+0x35/0x70
-finish_task_switch+0x158/0x260
-__schedule+0x2f6/0x840
-? hrtimer_start_range_ns+0x153/0x210
-schedule+0x32/0x80
-schedule_hrtimeout_range_clock+0x8a/0x100
-? hrtimer_init+0x120/0x120
-ep_poll+0x2f7/0x3a0
-? wake_up_q+0x60/0x60
-do_epoll_wait+0xa9/0xc0
-__x64_sys_epoll_wait+0x1a/0x20
-do_syscall_64+0x4e/0x110
-entry_SYSCALL_64_after_hwframe+0x44/0xa9
-RIP: 0033:0x7fdeb1e96c03
-...
-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
-Cc: acme@kernel.org
-Cc: Josh Hunt <johunt@akamai.com>
-Cc: bpuranda@akamai.com
-Cc: mingo@redhat.com
-Cc: jolsa@redhat.com
-Cc: tglx@linutronix.de
-Cc: namhyung@kernel.org
-Cc: alexander.shishkin@linux.intel.com
-Link: https://lkml.kernel.org/r/1566256411-18820-1-git-send-email-johunt@akamai.com
-Signed-off-by: Sasha Levin <sashal@kernel.org>
----
- arch/x86/kernel/cpu/perf_event_intel.c | 6 ++++++
- 1 file changed, 6 insertions(+)
-
-diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
-index 3572434a73cb7..c26c3e3357834 100644
---- a/arch/x86/kernel/cpu/perf_event_intel.c
-+++ b/arch/x86/kernel/cpu/perf_event_intel.c
-@@ -2721,6 +2721,11 @@ static unsigned bdw_limit_period(struct perf_event *event, unsigned left)
- return left;
- }
-
-+static u64 nhm_limit_period(struct perf_event *event, u64 left)
-+{
-+ return max(left, 32ULL);
-+}
-+
- PMU_FORMAT_ATTR(event, "config:0-7" );
- PMU_FORMAT_ATTR(umask, "config:8-15" );
- PMU_FORMAT_ATTR(edge, "config:18" );
-@@ -3326,6 +3331,7 @@ __init int intel_pmu_init(void)
- x86_pmu.pebs_constraints = intel_nehalem_pebs_event_constraints;
- x86_pmu.enable_all = intel_pmu_nhm_enable_all;
- x86_pmu.extra_regs = intel_nehalem_extra_regs;
-+ x86_pmu.limit_period = nhm_limit_period;
-
- x86_pmu.cpu_events = nhm_events_attrs;
-
---
-2.20.1
-