Re: [RFC PATCH v2 2/5] dma-mapping: Use the correct phys_to_dma() for DMA_RESTRICTED_POOL
From: Jason Gunthorpe
Date: Mon Mar 30 2026 - 18:35:48 EST
On Mon, Mar 30, 2026 at 08:47:41PM +0000, Mostafa Saleh wrote:
> > The force_dma_unencrypted() should only be done way up the call chain
> > where we decide to get a phys that is decrypted. Once we have a
> > decrypted phys it should be carried with an annotation throughout all
> > the other places.
>
> Can you please clarify what you mean by annotation in this context?
> As I believe any tracking in the vmemmap is a big NO.
It would have to be a flag pass along the phys, or phys & flag in a
struct or some kind of approach like that.
> As replied to the first patch I can attempt to implement this approach
> (by passing a flag around) and see how intrusive it would be.
I'm less concerned about intrusive and more about making this
understandable.
When we reach a function with a phys it should know what that phys is,
not call a bunch of random helpers to hopefully correctly guess what
it is, that's unmaintainable spaghetti even if it is fewer changes.
Jason