From: "David Laight" <David.Laight@ACULAB.COM>
To: "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"tiejun.chen" <tiejun.chen@windriver.com>
Cc: "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, 9 May 2013 14:28:13 +0100 [thread overview]
Message-ID: <AE90C24D6B3A694183C094C60CF0A2F6026B722F@saturn3.aculab.com> (raw)
In-Reply-To: <1368103062.25488.193.camel@pasglop>
> Some MPIC implementations tend to generate a spurrious IRQ in the case
> of level IRQs going away. IE. they still remember an event occurred and
> interrupt the processor, but on IACK return the spurious vector. However
> that isn't guaranteed to be the case and it is perfectly ok (and a good
> idea) for the PIC to just stop asserting the external interrupt line if
> the original device interrupt goes away (and it's configured as level
> sensitive).
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.
David
WARNING: multiple messages have this Message-ID (diff)
From: "David Laight" <David.Laight@ACULAB.COM>
To: "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
"tiejun.chen" <tiejun.chen@windriver.com>
Cc: 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, 9 May 2013 14:28:13 +0100 [thread overview]
Message-ID: <AE90C24D6B3A694183C094C60CF0A2F6026B722F@saturn3.aculab.com> (raw)
In-Reply-To: <1368103062.25488.193.camel@pasglop>
> Some MPIC implementations tend to generate a spurrious IRQ in the case
> of level IRQs going away. IE. they still remember an event occurred =
and
> interrupt the processor, but on IACK return the spurious vector. =
However
> that isn't guaranteed to be the case and it is perfectly ok (and a =
good
> idea) for the PIC to just stop asserting the external interrupt line =
if
> the original device interrupt goes away (and it's configured as level
> sensitive).
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.
David
WARNING: multiple messages have this Message-ID (diff)
From: "David Laight" <David.Laight@ACULAB.COM>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
"tiejun.chen" <tiejun.chen@windriver.com>
Cc: 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 13:28:13 +0000 [thread overview]
Message-ID: <AE90C24D6B3A694183C094C60CF0A2F6026B722F@saturn3.aculab.com> (raw)
In-Reply-To: <1368103062.25488.193.camel@pasglop>
> Some MPIC implementations tend to generate a spurrious IRQ in the case
> of level IRQs going away. IE. they still remember an event occurred and
> interrupt the processor, but on IACK return the spurious vector. However
> that isn't guaranteed to be the case and it is perfectly ok (and a good
> idea) for the PIC to just stop asserting the external interrupt line if
> the original device interrupt goes away (and it's configured as level
> sensitive).
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.
David
next prev parent reply other threads:[~2013-05-09 13:28 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 [this message]
2013-05-09 13:28 ` David Laight
2013-05-09 13:28 ` David Laight
2013-05-09 22:01 ` Benjamin Herrenschmidt
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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