On Thu, Mar 16, 2023 at 01:58:35PM -0700, John Harrison wrote: > On 3/15/2023 10:57, Greg KH wrote: > > On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: > > > On 3/15/2023 00:51, Greg KH wrote: > > > > On Mon, Mar 13, 2023 at 07:22:11PM -0700, john.c.harri...@intel.com > > > > wrote: > > > > > From: John Harrison <john.c.harri...@intel.com> > > > > > > > > > > Direction from hardware is that ring buffers should never be mapped > > > > > via the BAR on systems with LLC. There are too many caching pitfalls > > > > > due to the way BAR accesses are routed. So it is safest to just not > > > > > use it. > > > > > > > > > > Signed-off-by: John Harrison <john.c.harri...@intel.com> > > > > > Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound > > > > > anywhere") > > > > > Cc: Chris Wilson <ch...@chris-wilson.co.uk> > > > > > Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com> > > > > > Cc: Jani Nikula <jani.nik...@linux.intel.com> > > > > > Cc: Rodrigo Vivi <rodrigo.v...@intel.com> > > > > > Cc: Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com> > > > > > Cc: intel-gfx@lists.freedesktop.org > > > > > Cc: <sta...@vger.kernel.org> # v4.9+ > > > > > Tested-by: Jouni Högander <jouni.hogan...@intel.com> > > > > > Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com> > > > > > Link: > > > > > https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-3-john.c.harri...@intel.com > > > > > (cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919) > > > > > Signed-off-by: Jani Nikula <jani.nik...@intel.com> > > > > > (cherry picked from commit 85636167e3206c3fbd52254fc432991cc4e90194) > > > > > Signed-off-by: John Harrison <john.c.harri...@intel.com> > > > > > --- > > > > > drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 4 ++-- > > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > Also queued up for 5.10.y, you forgot that one :) > > > I'm still working through the backlog of them. > > > > > > Note that these patches must all be applied as a pair. The 'don't use > > > stolen' can be applied in isolation but won't totally fix the problem. > > > However, applying 'don't use BAR mappings' without applying the stolen > > > patch > > > first will results in problems such as the failure to boot that was > > > recently > > > reported and resulted in a revert in one of the trees. > > I do not understand, you only submitted 1 patch here, what is the > > "pair"? > The original patch series was two patches - > https://patchwork.freedesktop.org/series/114080/. One to not use stolen > memory and the other to not use BAR mappings. If the anti-BAR patch is > applied without the anti-stolen patch then the i915 driver will attempt to > access stolen memory directly which will fail. So both patches must be > applied and in the correct order to fix the problem of cache aliasing when > using BAR accesses on LLC systems. > > As above, I am working my way through the bunch of 'FAILED patch' emails. > The what-to-do instructions in those emails explicitly say to send the patch > individually in reply to the 'FAILED' message rather than as part of any > original series.
So what commits exactly in Linus's tree should be in these stable branches? Sorry, I still do not understand if we are missing one or if we need to revert something. confused, greg k-h