Re: [PATCH] KVM: arm64: vgic-its: Reject ITS_REGS offsets above U32_MAX

[Dan Carpenter <dan@cryspen.com>]

On Tue, Nov 10, 2026 at 10:59:42AM +0000, Marc Zyngier wrote:
> > +	if (offset > U32_MAX)
> > +		return -ENXIO;
> > +
> >  	/*
> >  	 * Although the spec supports upper/lower 32-bit accesses to
> >  	 * 64-bit ITS registers, the userspace ABI requires 64-bit
> 
> I think this is going in the wrong direction. Instead of capping the
> offset at an arbitrary value, the infrastructure should be able to
> deal with arbitrary offsets.
> 
> Could you try the following (untested) hack?
> 
> I also don't think this is worth a Cc stable (the worse case is that
> the VMM accesses an emulated register and sets something nonsensical),
> which it can always do.

Fair enough.  We are in arch/arm64/ so casting a u64 to a pointer and
back works.  Except for these two, the other callers pass values which
fit in a u32 so they aren't affected.

I'm going to remove some of your casts which aren't necessary and add
the uintptr_t cast back.

regards,
dan carpenter