From: Gleb Natapov <gleb@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>, kvm <kvm@vger.kernel.org>,
stable@kernel.org
Subject: Re: [patch 2/3] KVM: x86: disallow KVM_{SET,GET}_LAPIC without in kernel irqchip
Date: Wed, 28 Oct 2009 12:30:39 +0200 [thread overview]
Message-ID: <20091028103039.GU29477@redhat.com> (raw)
In-Reply-To: <20091028102041.GA24238@redhat.com>
On Wed, Oct 28, 2009 at 12:20:42PM +0200, Michael S. Tsirkin wrote:
> On Wed, Oct 28, 2009 at 11:32:00AM +0200, Avi Kivity wrote:
> > On 10/27/2009 07:50 PM, Michael S. Tsirkin wrote:
> >> Can the value of irqchip_in_kernel be changed by userspace
> >> after we have checked it? If yes, this check won't help ...
> >>
> >
> > A change from false to true is possible, but not the reverse.
>
> Hmm. If we want to rely on this, we have to play with
> memory barriers to write/read it. Doable, but hard to get right.
Why? If userspace is so racy that it tries to use vpic while other
thread creates it let it fail and burn in hell.
> Can we always have the irqchip object exist?
> It doesn't use a lot of memory, does it?
> Maybe have it inline, save an extra indirection on
> fastpath ...
>
> > --
> > error compiling committee.c: too many arguments to function
> --
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--
Gleb.
next prev parent reply other threads:[~2009-10-28 10:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-27 15:10 [patch 0/3] ioctl fixes Marcelo Tosatti
2009-10-27 15:10 ` [patch 1/3] KVM: x86: disallow multiple KVM_CREATE_IRQCHIP Marcelo Tosatti
2009-10-27 17:49 ` Michael S. Tsirkin
2009-10-27 15:10 ` [patch 2/3] KVM: x86: disallow KVM_{SET,GET}_LAPIC without in kernel irqchip Marcelo Tosatti
2009-10-27 17:50 ` Michael S. Tsirkin
2009-10-28 9:32 ` Avi Kivity
2009-10-28 10:20 ` Michael S. Tsirkin
2009-10-28 10:30 ` Gleb Natapov [this message]
2009-10-28 10:32 ` Michael S. Tsirkin
2009-10-28 10:39 ` Gleb Natapov
2009-10-28 10:34 ` Avi Kivity
2009-10-27 15:10 ` [patch 3/3] KVM: only clear irq_source_id if irqchip is present Marcelo Tosatti
2009-10-28 20:42 ` [patch 0/3] ioctl fixes v2 Marcelo Tosatti
2009-10-28 20:42 ` [patch 1/3] KVM: x86: disallow multiple KVM_CREATE_IRQCHIP Marcelo Tosatti
2009-10-29 9:32 ` Michael S. Tsirkin
2009-10-29 14:10 ` Marcelo Tosatti
2009-10-28 20:42 ` [patch 2/3] KVM: x86: disallow KVM_{SET,GET}_LAPIC without allocated in-kernel lapic Marcelo Tosatti
2009-10-28 20:42 ` [patch 3/3] KVM: only clear irq_source_id if irqchip is present Marcelo Tosatti
2009-10-29 15:44 ` [patch 0/3] ioctl fixes v3 Marcelo Tosatti
2009-10-29 15:44 ` [patch 1/3] KVM: x86: disallow multiple KVM_CREATE_IRQCHIP Marcelo Tosatti
2009-10-29 15:44 ` [patch 2/3] KVM: x86: disallow KVM_{SET,GET}_LAPIC without allocated in-kernel lapic Marcelo Tosatti
2009-10-29 15:44 ` [patch 3/3] KVM: only clear irq_source_id if irqchip is present Marcelo Tosatti
2009-11-02 9:53 ` [patch 0/3] ioctl fixes v3 Avi Kivity
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