From: Thomas Gleixner <tglx@linutronix.de>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Kar Hin Ong <kar.hin.ong@ni.com>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-x86_64@vger.kernel.org, linux-pci@vger.kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: "oneshot" interrupt causes another interrupt to be fired erroneously in Haswell system
Date: Tue, 5 Nov 2019 00:41:11 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.21.1911050017410.17054@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20191031230532.GA170712@google.com>
On Thu, 31 Oct 2019, Bjorn Helgaas wrote:
> On Thu, Oct 31, 2019 at 03:53:50AM +0000, Kar Hin Ong wrote:
> > I've an Intel Haswell system running Linux kernel v4.14 with
> > preempt_rt patch. The system contain 2 IOAPICs: IOAPIC 1 is on the
> > PCH where IOAPIC 2 is on the CPU.
> >
> > I observed that whenever a PCI device is firing interrupt (INTx) to
> > Pin 20 of IOAPIC 2 (GSI 44); the kernel will receives 2 interrupts:
> > 1. Interrupt from Pin 20 of IOAPIC 2 -> Expected
> > 2. Interrupt from Pin 19 of IOAPIC 1 -> UNEXPECTED, erroneously
> > triggered
> >
> > The unexpected interrupt is unhandled eventually. When this scenario
> > happen more than 99,000 times, kernel disables the interrupt line
> > (Pin 19 of IOAPIC 1) and causing device that has requested it become
> > malfunction.
> >
> > I managed to also reproduced this issue on RHEL 8 and Ubuntu 19-04
> > (without preempt_rt patch) after added "threadirqs" to the kernel
> > command line.
> >
> > After digging further, I noticed that the said issue is happened
> > whenever an interrupt pin on IOAPIC 2 is masked:
> > - Masking Pin 20 of IOAPIC 2 triggers Pin 19 of IOAPIC 1
> > - Masking Pin 22 of IOAPIC 2 triggers Pin 18 of IOAPIC 1
This is pretty much the same problem which we had analyzed and worked
around years ago.
> > From Intel Xeon Processor E5/E7 v3 Product Family External Design
> > Specification (EDS), Volume One: Architecture, section 13.1 (Legacy
> > PCI Interrupt Handling), it mention: "If the I/OxAPIC entry is
> > masked (via the 'mask' bit in the corresponding Redirection Table
> > Entry), then the corresponding PCI Express interrupt(s) is forwarded
> > to the legacy PCH"
Oh well. Really useful behaviour - NOT!
> > I would like to understand if my interpretation is make sense. If
> > yes, should the "oneshot" algorithm need to be updated to support
> > Haswell system?
No. You cannot change the oneshot algorithm.
The workarounds for this are enabled by PCI quirls and either
CONFIG_X86_REROUTE_FOR_BROKEN_BOOT_IRQS=y or 'ioapicreroute' on the command
line.
It might be wortha try to add the PCI ID of that box to the quirk list,
i.e. the PCI ID matches in drivers/pci/quirks.c which belong to the
function: quirk_reroute_to_boot_interrupts_intel().
Thanks,
tglx
next prev parent reply other threads:[~2019-11-04 23:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-31 3:53 "oneshot" interrupt causes another interrupt to be fired erroneously in Haswell system Kar Hin Ong
2019-10-31 23:05 ` Bjorn Helgaas
2019-11-01 7:46 ` Kar Hin Ong
2019-11-04 23:41 ` Thomas Gleixner [this message]
2019-11-07 9:38 ` Kar Hin Ong
2019-11-21 11:22 ` Kar Hin Ong
2020-01-15 23:05 ` Thomas Gleixner
2020-01-16 7:32 ` Kar Hin Ong
2020-01-16 10:01 ` Thomas Gleixner
2020-01-23 1:37 ` Sean V Kelley
2020-01-23 13:08 ` Thomas Gleixner
2020-02-09 15:37 ` Thomas Gleixner
2020-02-10 16:32 ` Sean V Kelley
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