Re: [PATCH v4 11/21] mm: add mmap_action_simple_ioremap()

Vlastimil Babka (SUSE)
2026-03-25T09:58:42Z

On 3/20/26 23:39, Lorenzo Stoakes (Oracle) wrote:
> Currently drivers use vm_iomap_memory() as a simple helper function for
> I/O remapping memory over a range starting at a specified physical address
> over a specified length.
>
> In order to utilise this from mmap_prepare, separate out the core logic
> into __simple_ioremap_prep(), update vm_iomap_memory() to use it, and add
> simple_ioremap_prepare() to do the same with a VMA descriptor object.
>
> We also add MMAP_SIMPLE_IO_REMAP and relevant fields to the struct
> mmap_action type to permit this operation also.
>
> We use mmap_action_ioremap() to set up the actual I/O remap operation once
> we have checked and figured out the parameters, which makes
> simple_ioremap_prepare() easy to implement.
>
> We then add mmap_action_simple_ioremap() to allow drivers to make use of
> this mode.
>
> We update the mmap_prepare documentation to describe this mode. Finally,
> we update the VMA tests to reflect this change.
>
> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>