Re: [PATCH 5/5] arm64: KVM: vgic-v2: Enable GICV access from HYP if access from guest is unsafe

Peter Maydell
2016-08-19T13:31:12Z

On 19 August 2016 at 14:05, Marc Zyngier <marc.zyngier@arm.com> wrote:
> On 19/08/16 13:53, Peter Maydell wrote:
>> Is it worth specifically saying "performance will be worse", or do we
>> expect this to only happen on systems where the h/w can't permit direct
>> access (as opposed to those with bad dt info) ?
>
> We cannot distinguish between the two, unfortunately. Even worse, ACPI
> only gives us a base address, and not the size of the region. So even if
> the HW was perfectly compliant with SBSA, we have to assume the worse case.

Right, but if we expect this is mostly going to be "you just have
to live with it on this hardware" there's less point in printing
an alarming message, whereas if there's a significant subset of
"dt is just wrong" cases then the alarm might help in getting them
fixed, maybe...

thanks
-- PMM