[RFC PATCH 28/33] irqchip/gic-v3-its: Support VPE doorbell invalidation even when !DirectLPI

[Thomas Gleixner]

On Tue, 17 Jan 2017, Marc Zyngier wrote:
> When we don't have the DirectLPI feature, we must work around the
> architecture shortcomings to be able to perform the required
> invalidation.
> 
> For this, we create a fake device whose sole purpose is to
> provide a way to issue a map/inv/unmap sequence (and the corresponding
> sync operations). That's 6 commands and a full serialization point
> to be able to do this.
> 
> You just have hope the hypervisor won't do that too often...
> 
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>

Reviewed-by: Thomas Gleixner <tglx at linutronix.de>