On Fri, Jun 17, 2022 at 03:06:25PM -0700, Nicolin Chen wrote: > On Fri, Jun 17, 2022 at 01:54:05AM -0700, Christoph Hellwig wrote: > > There is a bunch of code an comments in the iommu type1 code that > > suggest we can pin memory that is not page backed. > > Would you mind explaining the use case for pinning memory that > isn't page backed? And do we have such use case so far? Sorry, I should have deleted that sentence. I wrote it before spending some more time to dig through the code and all the locked memory has page backing. There just seem to be a lot of checks left inbetween if a pfn is page backed, mostly due to the pfn based calling convetions. > I can do that. I tried once, but there were just too much changes > inside type1 code that felt like a chain reaction. If we plan to > eventually replace with IOMMUFD implementations, these changes in > type1 might not be necessary, I thought. To make sure we keep full compatibility I suspect the final iommufd implementation has to be gradutally created from the existing code anyway.
