git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 1664ffee760a5d98952318fdd9b198fae396d660 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
   3 Date: Thu, 15 Oct 2020 13:21:35 +0100
   4 Subject: drm/i915: Mark ininitial fb obj as WT on eLLC machines to avoid rcu lockup during fbdev init
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   8
   9 From: Ville Syrjälä <ville.syrjala@linux.intel.com>
  10
  11 commit 1664ffee760a5d98952318fdd9b198fae396d660 upstream.
  12
  13 Currently we leave the cache_level of the initial fb obj
  14 set to NONE. This means on eLLC machines the first pin_to_display()
  15 will try to switch it to WT which requires a vma unbind+bind.
  16 If that happens during the fbdev initialization rcu does not
  17 seem operational which causes the unbind to get stuck. To
  18 most appearances this looks like a dead machine on boot.
  19
  20 Avoid the unbind by already marking the object cache_level
  21 as WT when creating it. We still do an excplicit ggtt pin
  22 which will rewrite the PTEs anyway, so they will match whatever
  23 cache level we set.
  24
  25 Cc: <stable@vger.kernel.org> # v5.7+
  26 Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
  27 Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2381
  28 Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
  29 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
  30 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
  31 Link: https://patchwork.freedesktop.org/patch/msgid/20201007120329.17076-1-ville.syrjala@linux.intel.com
  32 Link: https://patchwork.freedesktop.org/patch/msgid/20201015122138.30161-1-chris@chris-wilson.co.uk
  33 (cherry picked from commit d46b60a2e8d246f1f0faa38e52f4f5a73858c338)
  34 Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
  35 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  36
  37 ---
  38  drivers/gpu/drm/i915/display/intel_display.c |    8 ++++++++
  39  1 file changed, 8 insertions(+)
  40
  41 --- a/drivers/gpu/drm/i915/display/intel_display.c
  42 +++ b/drivers/gpu/drm/i915/display/intel_display.c
  43 @@ -3432,6 +3432,14 @@ initial_plane_vma(struct drm_i915_privat
  44         if (IS_ERR(obj))
  45                 return NULL;
  46
  47 +       /*
  48 +        * Mark it WT ahead of time to avoid changing the
  49 +        * cache_level during fbdev initialization. The
  50 +        * unbind there would get stuck waiting for rcu.
  51 +        */
  52 +       i915_gem_object_set_cache_coherency(obj, HAS_WT(i915) ?
  53 +                                           I915_CACHE_WT : I915_CACHE_NONE);
  54 +
  55         switch (plane_config->tiling) {
  56         case I915_TILING_NONE:
  57                 break;