Re: [PATCH] iommu/vt-d: Atomic breakdown of IOPT into finer granularity

[Jason Gunthorpe]

On Mon, Aug 14, 2023 at 08:10:16PM +0800, Jie Ji wrote:
> With the addition of IOMMU support for IO page fault, it's now possible
> to unpin the memory which DMA remapping. However, the lack of support
> for unmapping a subrange of the I/O page table (IOPT) in IOMMU can lead
> to some issues.
> 
> For instance, a virtual machine can establish IOPT of 2M/1G for better
> performance, while the host system enable swap and attempts to swap out
> some 4K pages. Unfortunately, unmap subrange of the large-page mapping
> will make IOMMU page walk to error level, and finally cause kernel crash.

Nothing in-kernel does something like this.

Jason