vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP

[Alexei Starovoitov]

On Fri, Mar 8, 2024 at 9:02 AM Christoph Hellwig <hch at infradead.org> wrote:
>
> On Fri, Mar 08, 2024 at 08:33:18AM -0800, Alexei Starovoitov wrote:
> > vmap_range_noflush() is static in mm/vmalloc.c
> > There is vmap_pages_range_noflush() that is in mm/internal.h,
> > but it needs pages instead of phys_addr_t.
> > Newly introduced vm_area_map_pages() needs struct vm_struct *area
> > and struct page **pages.
> > In this PCI case there is no vm_struct and no pages.
> > ioremap_page_range() is the only api that fits. afaict.
>
> Except that we want to enforce a vm_area with the ioremap flag for
> ioremap_page_range, and just adding a NULL check defeats that.
>
> The right long term thing would be to actually create a vm_area
> for the PCI_IOBASE region, but until then we just need a lower level
> API.  That's why I suggest to add a vmap_range() that is basically
> the ioremap_page_range before you added the checks, and make
> ioremap_page_range a wrapper around that that checks the area.

ok. Like the attached patch?

> If/when we get PCI_IOBASE handling converted to the proper
> vmalloc/ioremap areas we can remove that again as well as
> vunmap_range which is just used for PCI_IOBASE and other equivalent
> ISA_IO_BASE in powerpc and somewhat unusual case in arm64 that I
> need to look into a bit more.

The plan makes sense to me.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-mm-Introduce-vmap_page_range-to-be-used-by-PCI.patch
Type: application/octet-stream
Size: 3479 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20240308/4f42635b/attachment.obj>