Re: [PATCH 4.19.y] drm/i915/gem: Fix Virtual Memory mapping boundaries calculation

[Greg KH <greg@kroah.com>]

On Tue, Aug 13, 2024 at 05:28:15PM +0200, Greg KH wrote:
> On Tue, Aug 13, 2024 at 04:14:36PM +0200, Andi Shyti wrote:
> > Commit 8bdd9ef7e9b1b2a73e394712b72b22055e0e26c3 upstream.
> > 
> > Calculating the size of the mapped area as the lesser value
> > between the requested size and the actual size does not consider
> > the partial mapping offset. This can cause page fault access.
> > 
> > Fix the calculation of the starting and ending addresses, the
> > total size is now deduced from the difference between the end and
> > start addresses.
> > 
> > Additionally, the calculations have been rewritten in a clearer
> > and more understandable form.
> > 
> > Fixes: c58305af1835 ("drm/i915: Use remap_io_mapping() to prefault all PTE in a single pass")
> > Reported-by: Jann Horn <jannh@google.com>
> > Co-developed-by: Chris Wilson <chris.p.wilson@linux.intel.com>
> > Signed-off-by: Chris Wilson <chris.p.wilson@linux.intel.com>
> > Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Cc: Matthew Auld <matthew.auld@intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: <stable@vger.kernel.org> # v4.9+
> > Reviewed-by: Jann Horn <jannh@google.com>
> > Reviewed-by: Jonathan Cavitt <Jonathan.cavitt@intel.com>
> > [Joonas: Add Requires: tag]
> > Requires: 60a2066c5005 ("drm/i915/gem: Adjust vma offset for framebuffer mmap offset")
> > Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Link: https://patchwork.freedesktop.org/patch/msgid/20240802083850.103694-3-andi.shyti@linux.intel.com
> > (cherry picked from commit 97b6784753da06d9d40232328efc5c5367e53417)
> > Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_gem.c | 48 +++++++++++++++++++++++++++++----
> >  1 file changed, 43 insertions(+), 5 deletions(-)
> 
> Both now applied, thanks.

Wait, did you build this?  I get the following error:

  CC [M]  drivers/gpu/drm/i915/i915_gem.o
drivers/gpu/drm/i915/i915_gem.c: In function ‘set_address_limits’:
drivers/gpu/drm/i915/i915_gem.c:2034:18: error: ‘obj_offset’ undeclared (first use in this function); did you mean ‘iova_offset’?
 2034 |         start -= obj_offset;
      |                  ^~~~~~~~~~
      |                  iova_offset


I'll drop this now.

Can you fix this up and provide a working version?

thanks,

greg k-h