From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "tiejun.chen" <tiejun.chen@windriver.com>,
Caraman Mihai Claudiu-B02008 <B02008@freescale.com>,
kvm@vger.kernel.org, Wood Scott-B07421 <B07421@freescale.com>,
agraf@suse.de, kvm-ppc@vger.kernel.org,
Bhushan Bharat-R65777 <R65777@freescale.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts
Date: Fri, 10 May 2013 08:01:38 +1000 [thread overview]
Message-ID: <1368136898.3715.12.camel@pasglop> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B722F@saturn3.aculab.com>
On Thu, 2013-05-09 at 14:28 +0100, David Laight wrote:
> That will happen if the IRQ goes away while the cpu is performing
> the IACK sequence.
> If the IRQ goes away while the cpu has interrupts masked then
> the cpu won't start the interrupt sequence and then try to
> read a vector when no interrupt is pending.
Right, and get a spurrious vector which shouldn't be a big deal.
We tend to call that a "short interrupt". There have been many other
cases of short interrupts in the past, for example on some MPICs, when
distribution is enabled, they occasionally shoot an interrupt to more
than one CPU at once :-)
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Wood Scott-B07421 <B07421@freescale.com>,
kvm@vger.kernel.org,
Caraman Mihai Claudiu-B02008 <B02008@freescale.com>,
agraf@suse.de, kvm-ppc@vger.kernel.org,
"tiejun.chen" <tiejun.chen@windriver.com>,
Bhushan Bharat-R65777 <R65777@freescale.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts
Date: Fri, 10 May 2013 08:01:38 +1000 [thread overview]
Message-ID: <1368136898.3715.12.camel@pasglop> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B722F@saturn3.aculab.com>
On Thu, 2013-05-09 at 14:28 +0100, David Laight wrote:
> That will happen if the IRQ goes away while the cpu is performing
> the IACK sequence.
> If the IRQ goes away while the cpu has interrupts masked then
> the cpu won't start the interrupt sequence and then try to
> read a vector when no interrupt is pending.
Right, and get a spurrious vector which shouldn't be a big deal.
We tend to call that a "short interrupt". There have been many other
cases of short interrupts in the past, for example on some MPICs, when
distribution is enabled, they occasionally shoot an interrupt to more
than one CPU at once :-)
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "tiejun.chen" <tiejun.chen@windriver.com>,
Caraman Mihai Claudiu-B02008 <B02008@freescale.com>,
kvm@vger.kernel.org, Wood Scott-B07421 <B07421@freescale.com>,
agraf@suse.de, kvm-ppc@vger.kernel.org,
Bhushan Bharat-R65777 <R65777@freescale.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts
Date: Thu, 09 May 2013 22:01:38 +0000 [thread overview]
Message-ID: <1368136898.3715.12.camel@pasglop> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B722F@saturn3.aculab.com>
On Thu, 2013-05-09 at 14:28 +0100, David Laight wrote:
> That will happen if the IRQ goes away while the cpu is performing
> the IACK sequence.
> If the IRQ goes away while the cpu has interrupts masked then
> the cpu won't start the interrupt sequence and then try to
> read a vector when no interrupt is pending.
Right, and get a spurrious vector which shouldn't be a big deal.
We tend to call that a "short interrupt". There have been many other
cases of short interrupts in the past, for example on some MPICs, when
distribution is enabled, they occasionally shoot an interrupt to more
than one CPU at once :-)
Cheers,
Ben.
next prev parent reply other threads:[~2013-05-09 22:01 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-06 3:10 [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts Tiejun Chen
2013-05-06 3:10 ` Tiejun Chen
2013-05-06 3:10 ` Tiejun Chen
2013-05-06 3:13 ` tiejun.chen
2013-05-06 3:13 ` tiejun.chen
2013-05-06 3:13 ` tiejun.chen
2013-05-06 23:50 ` Scott Wood
2013-05-06 23:50 ` Scott Wood
2013-05-07 1:56 ` tiejun.chen
2013-05-07 1:56 ` tiejun.chen
2013-05-07 1:56 ` tiejun.chen
2013-05-07 2:06 ` Scott Wood
2013-05-07 2:06 ` Scott Wood
2013-05-07 2:43 ` tiejun.chen
2013-05-07 2:43 ` tiejun.chen
2013-05-07 2:43 ` tiejun.chen
2013-05-07 3:04 ` Scott Wood
2013-05-07 3:04 ` Scott Wood
2013-05-08 13:14 ` Caraman Mihai Claudiu-B02008
2013-05-08 13:14 ` Caraman Mihai Claudiu-B02008
2013-05-09 7:33 ` Bhushan Bharat-R65777
2013-05-09 7:33 ` Bhushan Bharat-R65777
2013-05-09 7:47 ` tiejun.chen
2013-05-09 7:47 ` tiejun.chen
2013-05-09 7:47 ` tiejun.chen
2013-05-09 7:51 ` Bhushan Bharat-R65777
2013-05-09 7:51 ` Bhushan Bharat-R65777
2013-05-09 8:04 ` tiejun.chen
2013-05-09 8:04 ` tiejun.chen
2013-05-09 8:04 ` tiejun.chen
2013-05-09 8:08 ` Kevin Hao
2013-05-09 8:08 ` Kevin Hao
2013-05-09 8:08 ` Kevin Hao
2013-05-09 8:12 ` Bhushan Bharat-R65777
2013-05-09 8:12 ` Bhushan Bharat-R65777
2013-05-09 8:17 ` tiejun.chen
2013-05-09 8:17 ` tiejun.chen
2013-05-09 8:17 ` tiejun.chen
2013-05-09 8:26 ` Bhushan Bharat-R65777
2013-05-09 8:26 ` Bhushan Bharat-R65777
2013-05-09 8:21 ` Kevin Hao
2013-05-09 8:21 ` Kevin Hao
2013-05-09 8:21 ` Kevin Hao
2013-05-09 12:26 ` Benjamin Herrenschmidt
2013-05-09 12:26 ` Benjamin Herrenschmidt
2013-05-09 12:26 ` Benjamin Herrenschmidt
2013-05-09 8:23 ` Bhushan Bharat-R65777
2013-05-09 8:23 ` Bhushan Bharat-R65777
2013-05-09 9:44 ` tiejun.chen
2013-05-09 9:44 ` tiejun.chen
2013-05-09 9:44 ` tiejun.chen
2013-05-09 10:00 ` Bhushan Bharat-R65777
2013-05-09 10:00 ` Bhushan Bharat-R65777
2013-05-09 10:18 ` [RFC][PATCH " tiejun.chen
2013-05-09 10:18 ` [RFC][KVM][PATCH " tiejun.chen
2013-05-09 10:18 ` tiejun.chen
2013-05-09 11:21 ` Bhushan Bharat-R65777
2013-05-09 11:21 ` Bhushan Bharat-R65777
2013-05-09 11:35 ` tiejun.chen
2013-05-09 11:35 ` tiejun.chen
2013-05-09 11:35 ` tiejun.chen
2013-05-09 12:37 ` [RFC][PATCH " Benjamin Herrenschmidt
2013-05-09 12:37 ` [RFC][KVM][PATCH " Benjamin Herrenschmidt
2013-05-09 12:37 ` Benjamin Herrenschmidt
2013-05-09 13:28 ` David Laight
2013-05-09 13:28 ` David Laight
2013-05-09 13:28 ` David Laight
2013-05-09 22:01 ` Benjamin Herrenschmidt [this message]
2013-05-09 22:01 ` Benjamin Herrenschmidt
2013-05-09 22:01 ` Benjamin Herrenschmidt
2013-05-09 14:13 ` Chen, Tiejun
2013-05-09 14:13 ` Chen, Tiejun
2013-05-09 14:13 ` Chen, Tiejun
2013-05-09 21:27 ` Scott Wood
2013-05-09 21:27 ` Scott Wood
2013-05-09 22:07 ` [RFC][PATCH " Benjamin Herrenschmidt
2013-05-09 22:07 ` [RFC][KVM][PATCH " Benjamin Herrenschmidt
2013-05-09 22:07 ` Benjamin Herrenschmidt
2013-05-09 22:13 ` Scott Wood
2013-05-09 22:13 ` Scott Wood
2013-05-10 14:12 ` Kevin Hao
2013-05-10 14:12 ` Kevin Hao
2013-05-10 14:12 ` Kevin Hao
2013-05-10 21:49 ` Benjamin Herrenschmidt
2013-05-10 21:49 ` Benjamin Herrenschmidt
2013-05-10 21:49 ` Benjamin Herrenschmidt
2013-05-10 21:50 ` Benjamin Herrenschmidt
2013-05-10 21:50 ` Benjamin Herrenschmidt
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