Re: [PATCH v2 02/10] iommu: Introduce a new iommu_group_replace_domain() API

[Jason Gunthorpe]

On Mon, Feb 13, 2023 at 02:24:40AM +0000, Tian, Kevin wrote:

> > This is because the cache tag and the io page table top are in
> > different 64 bit words so atomic writes don't cover both, and thus the
> > IOMMU HW could tear the two stores and mismatch the cache tag to the
> > table top. This would corrupt the cache.
> 
> VT-d spec recommends using 128bit cmpxchg instruction to update
> page table pointer and DID together.

Oh really? Such a thing exists? That neat!

Jason