RE: [PATCH RFC 00/19] IOMMUFD Dirty Tracking

Tian, Kevin
2022-05-06T03:18:02Z

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Thursday, May 5, 2022 9:55 PM
>
> On Thu, May 05, 2022 at 11:03:18AM +0000, Tian, Kevin wrote:
>
> > iiuc the purpose of 'write-protection' here is to capture in-fly dirty pages
> > in the said race window until unmap and iotlb is invalidated is completed.
>
> No, the purpose is to perform "unmap" without destroying the dirty bit
> in the process.
>
> If an IOMMU architecture has a way to render the page unmaped and
> flush back the dirty bit/not destroy then it doesn't require a write
> protect pass.
>

Yes, I see the point now. As you said let's consider it only when
there is a real use case requiring such atomicity.