From: Avi Kivity <avi@redhat.com>
To: Gregory Haskins <gregory.haskins@gmail.com>
Cc: Gleb Natapov <gleb@redhat.com>,
Gregory Haskins <ghaskins@novell.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
alacrityvm-devel@lists.sourceforge.net
Subject: Re: [KVM PATCH 1/2] KVM: Directly inject interrupts via irqfd
Date: Thu, 22 Oct 2009 17:07:45 +0200 [thread overview]
Message-ID: <4AE07541.8060903@redhat.com> (raw)
In-Reply-To: <4ADF2BDD.40706@gmail.com>
On 10/21/2009 05:42 PM, Gregory Haskins wrote:
> I believe Avi, Michael, et. al. were in agreement with me on that design
> choice. I believe the reason is that there is no good way to do EOI/ACK
> feedback within the constraints of an eventfd pipe which would be
> required for the legacy pin-type interrupts. Therefore, we won't even
> bother trying. High-performance subsystems will use irqfd/msi, and
> legacy emulation can use the existing injection code (which includes the
> necessary feedback for ack/eoi).
>
>
Right. But we don't actually prevent anyone using non-msi with irqfd,
which can trigger the bad lock usage from irq context, with a nice boom
afterwards. So we need to either prevent it during registration, or to
gracefully handle it afterwards.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2009-10-22 15:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-21 14:34 [KVM PATCH 0/2] irqfd enhancements Gregory Haskins
2009-10-21 14:34 ` [KVM PATCH 1/2] KVM: Directly inject interrupts via irqfd Gregory Haskins
2009-10-21 15:26 ` Gleb Natapov
2009-10-21 15:34 ` Gregory Haskins
2009-10-21 15:36 ` Gleb Natapov
2009-10-21 15:42 ` Gregory Haskins
2009-10-22 15:07 ` Avi Kivity [this message]
2009-10-22 15:14 ` Gregory Haskins
2009-10-22 15:19 ` Avi Kivity
2009-10-22 15:33 ` Gregory Haskins
2009-10-21 14:34 ` [KVM PATCH 2/2] KVM: Remove unecessary irqfd-cleanup-wq Gregory Haskins
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