Re: [PATCH] xen/arm: acpi: Support memory reserve configuration table

[Leo Yan <leo.yan@xxxxxxxxxx>]

On Thu, Aug 25, 2022 at 10:40:41PM +0800, Leo Yan wrote:

[...]

> > > But here I still cannot create the concept that how GIC RD tables play
> > > roles to support the para virtualization or passthrough mode.
> >
> > I am not sure what you are actually asking. The pending tables are just
> > memory you give to the GICv3 to record the state of the interrupts.
>
> For more specific, Xen has its own RD pending table, and we can use
> this pending table to set state for SGI/PPI/LPI for a specific CPU
> interface.  Xen works as hypervisor, it saves and restores the pending
> table according to switched in VM context, right?
>
> On the other hand, what's the purpose for Linux kernel's GIC RD
> pending table?  Is it only used for nested virtulisation?  I mean if
> Linux kernel's GIC RD pending table is not used for the drivers in
> Dom0 or DomU, then it's useless to pass it from the primary kernel to
> secondary kernel; as result, we don't need to reserve the persistent
> memory for the pending table in this case.

I don't receive further confirmation from Marc, anyway, I tried to cook
a kernel patch to mute the kernel oops [1].

Hope this is not too arbitrary and we can move forward a bit.

Thanks,
Leo

[1] https://lore.kernel.org/lkml/20220906024040.503764-1-leo.yan@xxxxxxxxxx/T/#u