From e5d2b75add2157fc0735f5630252405829aa1cd2 Mon Sep 17 00:00:00 2001
From: Jason Ekstrand <jason@jlekstrand.net>
Date: Fri, 23 Jul 2021 12:21:39 -0500
Subject: drm/i915/gem/ttm: Only call __i915_gem_object_set_pages if needed
Git-commit: 75e382850b7ea516cbeaecf2dd22dd040e144ad9
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

__i915_ttm_get_pages does two things.  First, it calls ttm_bo_validate()
to check the given placement and migrate the BO if needed.  Then, it
updates the GEM object to match, in case the object was migrated.  If
no migration occured, however, we might still have pages on the GEM
object in which case we don't need to fetch them from TTM and call
__i915_gem_object_set_pages.  This hasn't been a problem before because
the primary user of __i915_ttm_get_pages is __i915_gem_object_get_pages
which only calls it if the GEM object doesn't have pages.

However, i915_ttm_migrate also uses __i915_ttm_get_pages to do the
migration so this meant it was unsafe to call on an already populated
object.  This patch checks i915_gem_object_has_pages() before trying to
__i915_gem_object_set_pages so i915_ttm_migrate is safe to call, even on
populated objects.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210723172142.3273510-6-jason@jlekstrand.net
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 8eefe3e109f1..35eedc14f522 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -661,13 +661,14 @@ static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
 		i915_ttm_adjust_gem_after_move(obj);
 	}
 
-	GEM_WARN_ON(obj->mm.pages);
-	/* Object either has a page vector or is an iomem object */
-	st = bo->ttm ? i915_ttm_tt_get_st(bo->ttm) : obj->ttm.cached_io_st;
-	if (IS_ERR(st))
-		return PTR_ERR(st);
+	if (!i915_gem_object_has_pages(obj)) {
+		/* Object either has a page vector or is an iomem object */
+		st = bo->ttm ? i915_ttm_tt_get_st(bo->ttm) : obj->ttm.cached_io_st;
+		if (IS_ERR(st))
+			return PTR_ERR(st);
 
-	__i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl));
+		__i915_gem_object_set_pages(obj, st, i915_sg_dma_sizes(st->sgl));
+	}
 
 	return ret;
 }
-- 
2.38.1