Re: [PATCH 1/2] KVM: arm64: vgic: Forbid invalid userspace Redistributor accesses

[Zenghui Yu]

Hi Marc,

On 2020/11/16 22:10, Marc Zyngier wrote:
> > My take is that only if the "[Re]Distributor base address" is specified
> > in the system memory map, will the user-provided kvm_device_attr.offset
> > make sense. And we can then handle the access to the register which is
> > defined by "base address + offset".
>
> I'd tend to agree, but it is just that this is a large change at -rc4.
> I'd rather have a quick fix for 5.10, and a more invasive change for 5.11,
> spanning all the possible vgic devices.

So you prefer fixing it by "return a value that doesn't have the Last
bit set" for v5.10? I'm ok with it and can send v2 for it.

Btw, looking again at the way we handle the user-reading of GICR_TYPER

	vgic_mmio_read_v3r_typer(vcpu, addr, len)

it seems that @addr is actually the *offset* of GICR_TYPER (0x0008) and
@addr is unlikely to be equal to last_rdist_typer, which is the *GPA* of
the last RD. Looks like the user-reading of GICR_TYPER.Last is always
broken?


Thanks,
Zenghui