[PATCH v2] KVM: ARM: vgic: plug irq injection race

[Christoffer Dall]

On Thu, Mar 20, 2014 at 04:47:15PM +0000, Marc Zyngier wrote:
> As it stands, nothing prevents userspace from injecting an interrupt
> before the guest's GIC is actually initialized.
> 
> This goes unnoticed so far (as everything is pretty much statically
> allocated), but ends up exploding in a spectacular way once we switch
> to a more dynamic allocation (the GIC data structure isn't there yet).
> 
> The fix is to test for the "ready" flag in the VGIC distributor before
> trying to inject the interrupt. Note that in order to avoid breaking
> userspace, we have to ignore what is essentially an error.
> 
> Also, move the setting of the flag out of the critical section,
> which will ensure the visibility of the initialized data-structure
> before the flag is actually set.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>

Acked-by: Christoffer Dall <christoffer.dall at linaro.org>