RE: [PATCH 1/3] KVM: arm64: Implement vGICv3 distributor and redistributor access from userspace

[Pavel Fedin <p.fedin@samsung.com>]

 Hello!

> > +	len = vgic_v3_get_reg_size(attr);
> > +	if (len < 0)
> > +		return len;
> >
> > -	return -ENXIO;
> > +	ret = vgic_v3_attr_regs_access(dev, attr, (len == 8) ? (void *)&reg64 :
> > +					(void *)&reg, len, false);
> 
> this use of the ternary operator is terrible, but it should be solved if
> you always use a u64 for the reg parameter.

 I also dislike this, but this is the best thing i could invent. This is dictated by put_user() and
get_user(), which rely on typeof() of their arguments. Well, i could do some castings, but they are
no less ugly, and would give more headache to bigendian systems.
However, what about doing the same thing as GET/SET_ONE_REG does by just assuming that everything is
64-bit wide? This would automatically resolve two other issues you have commented on. By the way,
handling it in userspace would also be simpler.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia