Re: [PATCH] KVM: Ensure all vcpus are consistent with in-kernel irqchip settings

[Avi Kivity <avi@redhat.com>]

On 03/06/2012 07:30 AM, Michael Ellerman wrote:
> On Mon, 2012-03-05 at 14:29 +0200, Avi Kivity wrote:
> > If some vcpus are created before KVM_CREATE_IRQCHIP, then
> > irqchip_in_kernel() and vcpu->arch.apic will be inconsistent, leading
> > to potential NULL pointer dereferences.
> > 
> > Fix by:
> > - ensuring that no vcpus are installed when KVM_CREATE_IRQCHIP is called
> > - ensuring that a vcpu has an apic if it is installed after KVM_CREATE_IRQCHIP
> > 
> > This is somewhat long winded because vcpu->arch.apic is created without
> > kvm->lock held.
>
> Hi Avi,
>
> Thanks for following up on this. This looks OK to me.
>
> I wonder if we will end up needing to add other sanity tests at the same
> point, ie. when we install the vcpu, in which case we might need a
> generic "sanity hook". But better to keep it specific until we need
> something generalised.

Right, ARM will also have the same problem (with/without GIC).

> When we do irqchip-in-kernel on powerpc we'll need to rework the #ifdef
> in kvm_host.h, because we don't want CONFIG_KVM_APIC_ARCHITECTURE, but
> we will need our own kvm_vcpu_compatible(). But again we'll do that at
> the time.
>

-- 
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