Re: [PATCH] KVM: arm64: vgic: fix GICR_STATUSR in vgic_v3_rd_registers

Jia Qingtong
2024-09-30T06:20:45Z

On 29 Sep 10:38, Marc Zyngier wrote:
> On Sun, 29 Sep 2024 05:39:35 +0100,
> jiaqingtong97@gmail.com wrote:
> >
> > From: Jia Qingtong <jiaqingtong@huawei.com>
> >
> > vgic_uaccess use bsearch search regs in vgic_io_device.regions, but the
> > GICR_STATUSR have wrong order in vgic_v3_rd_registers.
> > When check all vgic_register_region, it turned out that only
> > vgic_v3_rd_registers has this problem.
> >
> > It's harmless since vgic_uaccess behaves as RAZ&WI when it can't find the
> > specified reg. This is exactly the same as the behavior of the GICR_STATUSR
> > register.
> >
> > So just move GICR_STATUSR to the right place.
>
> That looks correct, but I think we should have some code that ensures
> that these tables are correct at boot time, just like we're doing for
> the system registers. Or completely remove our reliance on bsearch().
>
struct vgic_register_region was defined in vgic-{its,mmio-v2,mmio-v3},
do you think it's appropriate to extern and check tables's item order in
vgic-init.c's kvm_vgic_hyp_init?.

> Another thing is that GICD_STATUSR looks pretty wrong. It is handled
> as RAO, but we never clear any "error" (it is WI). This has been buggy
> since GICv3 save/restore was added, 7 years ago.
>
Let's change it to RAZ? We will implement the complete logic when someone
really needs this feature.

> Do you mind spinning a series fixing this up?
>
Sure.

> Thanks,
>
> M.
>
> --
> Without deviation from the norm, progress is not possible.

--
Thanks,
Qingtong