From: Scott Wood <scottwood@freescale.com>
To: Tiejun Chen <tiejun.chen@windriver.com>
Cc: agraf@suse.de, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [v1][PATCH 1/1] KVM: PPC: disable preemption when using hard_irq_disable()
Date: Wed, 10 Jul 2013 19:15:40 +0000 [thread overview]
Message-ID: <1373483740.8183.223@snotra> (raw)
In-Reply-To: <1373436139-27998-1-git-send-email-tiejun.chen@windriver.com> (from tiejun.chen@windriver.com on Wed Jul 10 01:02:19 2013)
On 07/10/2013 01:02:19 AM, Tiejun Chen wrote:
> We should ensure the preemption cannot occur while calling get_paca()
> insdide hard_irq_disable(), otherwise the paca_struct may be the
> wrong one just after. And btw, we may update timing stats in this
> case.
The soft-ee mechanism depends on accessing the PACA directly via r13 to
avoid this. We probably should be using inline asm to read was_enabled
rather than hoping the compiler doesn't do anything silly.
Plus what Alex said, regarding this patch specifically.
-Scott
WARNING: multiple messages have this Message-ID (diff)
From: Scott Wood <scottwood@freescale.com>
To: Tiejun Chen <tiejun.chen@windriver.com>
Cc: linuxppc-dev@lists.ozlabs.org, agraf@suse.de,
kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [v1][PATCH 1/1] KVM: PPC: disable preemption when using hard_irq_disable()
Date: Wed, 10 Jul 2013 14:15:40 -0500 [thread overview]
Message-ID: <1373483740.8183.223@snotra> (raw)
In-Reply-To: <1373436139-27998-1-git-send-email-tiejun.chen@windriver.com> (from tiejun.chen@windriver.com on Wed Jul 10 01:02:19 2013)
On 07/10/2013 01:02:19 AM, Tiejun Chen wrote:
> We should ensure the preemption cannot occur while calling get_paca()
> insdide hard_irq_disable(), otherwise the paca_struct may be the
> wrong one just after. And btw, we may update timing stats in this =20
> case.
The soft-ee mechanism depends on accessing the PACA directly via r13 to =20
avoid this. We probably should be using inline asm to read was_enabled =20
rather than hoping the compiler doesn't do anything silly.
Plus what Alex said, regarding this patch specifically.
-Scott=
WARNING: multiple messages have this Message-ID (diff)
From: Scott Wood <scottwood@freescale.com>
To: Tiejun Chen <tiejun.chen@windriver.com>
Cc: <agraf@suse.de>, <kvm-ppc@vger.kernel.org>, <kvm@vger.kernel.org>,
<linuxppc-dev@lists.ozlabs.org>
Subject: Re: [v1][PATCH 1/1] KVM: PPC: disable preemption when using hard_irq_disable()
Date: Wed, 10 Jul 2013 14:15:40 -0500 [thread overview]
Message-ID: <1373483740.8183.223@snotra> (raw)
In-Reply-To: <1373436139-27998-1-git-send-email-tiejun.chen@windriver.com> (from tiejun.chen@windriver.com on Wed Jul 10 01:02:19 2013)
On 07/10/2013 01:02:19 AM, Tiejun Chen wrote:
> We should ensure the preemption cannot occur while calling get_paca()
> insdide hard_irq_disable(), otherwise the paca_struct may be the
> wrong one just after. And btw, we may update timing stats in this
> case.
The soft-ee mechanism depends on accessing the PACA directly via r13 to
avoid this. We probably should be using inline asm to read was_enabled
rather than hoping the compiler doesn't do anything silly.
Plus what Alex said, regarding this patch specifically.
-Scott
next prev parent reply other threads:[~2013-07-10 19:15 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-10 6:02 [v1][PATCH 1/1] KVM: PPC: disable preemption when using hard_irq_disable() Tiejun Chen
2013-07-10 6:02 ` Tiejun Chen
2013-07-10 9:49 ` Alexander Graf
2013-07-10 9:49 ` Alexander Graf
2013-07-11 2:48 ` tiejun.chen
2013-07-11 2:48 ` tiejun.chen
2013-07-11 9:49 ` Alexander Graf
2013-07-11 9:49 ` Alexander Graf
2013-07-11 12:28 ` Benjamin Herrenschmidt
2013-07-11 12:28 ` Benjamin Herrenschmidt
2013-07-11 12:47 ` Alexander Graf
2013-07-11 12:47 ` Alexander Graf
2013-07-11 12:54 ` Benjamin Herrenschmidt
2013-07-11 12:54 ` Benjamin Herrenschmidt
2013-07-11 13:07 ` Alexander Graf
2013-07-11 13:07 ` Alexander Graf
2013-07-12 0:19 ` Benjamin Herrenschmidt
2013-07-12 0:19 ` Benjamin Herrenschmidt
2013-07-12 2:13 ` tiejun.chen
2013-07-12 2:13 ` tiejun.chen
2013-07-12 3:57 ` Benjamin Herrenschmidt
2013-07-12 3:57 ` Benjamin Herrenschmidt
2013-07-12 4:54 ` tiejun.chen
2013-07-12 4:54 ` tiejun.chen
2013-07-14 4:13 ` Benjamin Herrenschmidt
2013-07-14 4:13 ` Benjamin Herrenschmidt
2013-07-15 3:04 ` tiejun.chen
2013-07-15 3:04 ` tiejun.chen
2013-07-10 19:15 ` Scott Wood [this message]
2013-07-10 19:15 ` Scott Wood
2013-07-10 19:15 ` Scott Wood
2013-07-11 2:59 ` tiejun.chen
2013-07-11 3:00 ` tiejun.chen
2013-07-11 3:00 ` tiejun.chen
2013-07-11 14:13 ` Scott Wood
2013-07-11 14:13 ` Scott Wood
[not found] <1373559480.8183.258@snotra>
2013-07-12 0:30 ` Benjamin Herrenschmidt
2013-07-12 0:30 ` Benjamin Herrenschmidt
[not found] ` <FB21594A-C233-4A97-8503-E2A1275F8F17@suse.de>
[not found] ` <1373560585.8183.261@snotra>
2013-07-12 3:22 ` tiejun.chen
2013-07-12 3:22 ` tiejun.chen
[not found] <1373651433.8183.276@snotra>
2013-07-12 23:05 ` Benjamin Herrenschmidt
2013-07-12 23:05 ` Benjamin Herrenschmidt
2013-07-15 2:20 ` tiejun.chen
2013-07-15 2:20 ` tiejun.chen
2013-07-15 2:47 ` Benjamin Herrenschmidt
2013-07-15 2:47 ` Benjamin Herrenschmidt
2013-07-15 3:03 ` tiejun.chen
2013-07-15 3:03 ` tiejun.chen
[not found] ` <1373909248.8183.303@snotra>
2013-07-16 2:15 ` tiejun.chen
2013-07-16 2:15 ` tiejun.chen
2013-07-15 2:25 ` tiejun.chen
2013-07-15 2:25 ` tiejun.chen
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