From: Marcelo Tosatti <mtosatti@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: kvm@vger.kernel.org
Subject: Re: [patch 4/8] KVM: x86: replace hrtimer based timer emulation
Date: Wed, 8 Jul 2009 13:47:12 -0300 [thread overview]
Message-ID: <20090708164712.GB6867@amt.cnet> (raw)
In-Reply-To: <20090708164057.GT28046@redhat.com>
On Wed, Jul 08, 2009 at 07:40:57PM +0300, Gleb Natapov wrote:
> On Wed, Jul 08, 2009 at 01:37:39PM -0300, Marcelo Tosatti wrote:
> > On Wed, Jul 08, 2009 at 07:29:58PM +0300, Gleb Natapov wrote:
> > > On Wed, Jul 08, 2009 at 10:17:21AM -0300, Marcelo Tosatti wrote:
> > > > (but yes, bypassing the irq injection system its not a very beatiful
> > > > shortcut, but its done in other places too eg i8254.c NMI injection via
> > > > all cpus LINT0).
> > > >
> > > I've looked at this. Why do you say i8254.c NMI injection bypass the irq
> > > injection system? It look to me like it uses usual way to send interrupt
> > > to all cpus.
> >
> > It goes through apic_accept_irq so its somewhat fine. But it accesses
> > the lapics of other vcpus locklessly (which does not happen via
> > kvm_set_irq path due to irq_lock protection).
> Ah, that the bug then. But otherwise it goes through usual interrupt
> logic. Do you know why the lock is missing? Due to potential deadlock or
> we just forget to lock?
There is no lock to protect the lapics right, normally isr setting is
lockless which is fine, but kvm_apic_local_deliver also reads a
register. Hum, should be fine though.
next prev parent reply other threads:[~2009-07-08 16:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-06 1:55 [patch 0/8] RFC: in-kernel timer emulation changes Marcelo Tosatti
2009-07-06 1:55 ` [patch 1/8] KVM: timer interface unification Marcelo Tosatti
2009-07-08 13:33 ` Avi Kivity
2009-07-06 1:55 ` [patch 2/8] KVM: move lapic timer ack to EOI handler Marcelo Tosatti
2009-07-06 1:55 ` [patch 3/8] KVM: x86: per-vcpu timer list Marcelo Tosatti
2009-07-06 1:55 ` [patch 4/8] KVM: x86: replace hrtimer based timer emulation Marcelo Tosatti
2009-07-08 12:58 ` Gleb Natapov
2009-07-08 13:17 ` Marcelo Tosatti
2009-07-08 13:39 ` Gleb Natapov
2009-07-08 15:42 ` Marcelo Tosatti
2009-07-08 16:13 ` Gleb Natapov
2009-07-08 16:29 ` Gleb Natapov
2009-07-08 16:37 ` Marcelo Tosatti
2009-07-08 16:40 ` Gleb Natapov
2009-07-08 16:47 ` Marcelo Tosatti [this message]
2009-07-08 13:41 ` Avi Kivity
2009-07-08 16:24 ` Marcelo Tosatti
2009-07-08 16:36 ` Avi Kivity
2009-07-06 1:55 ` [patch 5/8] KVM: timer: honor noreinject tunable Marcelo Tosatti
2009-07-06 1:55 ` [patch 6/8] KVM: timer: optimize next_timer_event and vcpu_arm_exit Marcelo Tosatti
2009-07-06 1:55 ` [patch 7/8] KVM: PIT: removed unused code Marcelo Tosatti
2009-07-06 1:55 ` [patch 8/8] kvmctl: time testcase Marcelo Tosatti
2009-07-08 13:43 ` [patch 0/8] RFC: in-kernel timer emulation changes Avi Kivity
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