Re: [PATCH v5 01/23] irqchip/gic-v3: Use SGIs without active state if offered

Zenghui Yu
2020-03-12T06:30:46Z

Hi Marc,

On 2020/3/5 4:33, Marc Zyngier wrote:
> To allow the direct injection of SGIs into a guest, the GICv4.1
> architecture has to sacrifice the Active state so that SGIs look
> a lot like LPIs (they are injected by the same mechanism).
>
> In order not to break existing software, the architecture gives
> offers guests OSs the choice: SGIs with or without an active
> state. It is the hypervisors duty to honor the guest's choice.
>
> For this, the architecture offers a discovery bit indicating whether
> the GIC supports GICv4.1 SGIs (GICD_TYPER2.nASSGIcap), and another
> bit indicating whether the guest wants Active-less SGIs or not
> (controlled by GICD_CTLR.nASSGIreq).

I still can't find the description of these two bits in IHI0069F.
Are they actually architected and will be available in the future
version of the spec? I want to confirm it again since this has a
great impact on the KVM code, any pointers?

Thanks,
Zenghui