Re: [v2 PATCH] iommu/arm-smmu-v3: Fix L1 stream table index calculation for 32-bit sid size

From: Jason Gunthorpe
Date: Fri Oct 04 2024 - 12:14:24 EST


On Fri, Oct 04, 2024 at 09:05:46AM -0700, Yang Shi wrote:
>
>
> On 10/4/24 5:43 AM, Jason Gunthorpe wrote:
> > On Thu, Oct 03, 2024 at 08:31:23AM -0700, Yang Shi wrote:
> > > If I understand correctly, the check is mainly used to avoid the u64 -> u32
> > > overflow. This check guarantee no overflow. If some crazy hardware really
> > > requests that large memory, the allocation will fail.
> > Sure, the kalloc will print a warn on anyhow if it is too big
>
> Thank you. Will spin a new revision.

Oh wait a sec, it is not so simple, the 31 is too big because the
multiply will overflow or truncate to size_t too. This is why I picked
something lower.

Jason