Re: [PATCH] drm: remove pgprot_decrypted() before calls to io_remap_pfn_range()

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Nov 05, 2020 at 08:17:46PM +0100, Daniel Vetter wrote:
> On Thu, Nov 05, 2020 at 01:00:19PM -0400, Jason Gunthorpe wrote:
> > commit f8f6ae5d077a ("mm: always have io_remap_pfn_range() set
> > pgprot_decrypted()") moves the pgprot_decrypted() into
> > io_remap_pfn_range(). Delete any, now confusing, open coded calls that
> > directly precede io_remap_pfn_range():
> > 
> > - drm_io_prot() is only in drm_mmap_locked() to call io_remap_pfn_range()
> > 
> > - fb_mmap() immediately calls vm_iomap_memory() which is a convenience
> >   wrapper for io_remap_pfn_range()
> > 
> > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> >  drivers/gpu/drm/drm_vm.c         | 3 ---
> >  drivers/video/fbdev/core/fbmem.c | 5 -----
> >  2 files changed, 8 deletions(-)
> > 
> > rc3 will have the dependent patch, this should not be merged to DRM until it
> > has the rc3 commits.
> > 
> > There are three other pgprot_decrypted() calls in DRM, I could not figure out
> > what was what there, but other than very special cases I would expect code to
> > use io_remap_pfn_range() instead.
> 
> There's 4 now, I think linux-next added one. It's another io_remap_pfn
> 
> Of the three you mentioned we have:
> - ttm and i915 use vm_insert_pfn (and ttm also can do also do pud_mkhuge
>   entries)

You can't insert IO memory with vmf_insert_pfn_pmd_prot() (it
doesn't set the special flag) so why does it need decrypted?

Jason