[PATCH v4 38/48] Documentation: KVM: Add docs for KVM_DEV_ARM_VGIC_GRP_IST

[Sascha Bischoff]

Hi Fuad,

On Mon, 2026-07-27 at 20:26 +0100, Fuad Tabba wrote:
> Hi Sascha,
> 
> On Fri, 24 Jul 2026 at 11:59, Sascha Bischoff
> <Sascha.Bischoff at arm.com> wrote:
> ...
> > +      -ENOENT      A userspace SPI IST buffer was supplied, but
> > there is no SPI
> > +                   IST to serialise/unserialise
> 
> I do not think -ENOENT can be returned.

Yeah, after the rework that I did last time I don't think it can be
either.

> The branch producing it in
> `vgic_v5_get_spi_ist_desc()` needs `!ist->base && userspace_buf`, but
> `vgic_v5_validate_ist_attr()` runs first at both call sites and
> rejects a zero `spi_ist_addr`, and a VGICv5 VM always has an SPI IST
> by the time this attribute is reachable. That leaves the
> `userspace_buf` argument without an effect either, so this may be a
> code fix rather than a documentation one.

Agreed. I've removed `userspace_buf` as it is completely redundant now.
The paths return -ENOENT were also unreachable now, so I've pruned
those too, as well as dropping it from the documentation.

> 
> Cheers,
> /fuad

Thanks,
Sascha