[Intel-gfx] [PATCH v12 2/4] drm/i915: Reserve some kernel space per vm

[Jonathan Cavitt]

Reserve two pages in each vm for kernel space to use for things
such as workarounds.

Signed-off-by: Jonathan Cavitt <jonathan.cav...@intel.com>
Suggested-by: Chris Wilson <chris.p.wil...@linux.intel.com>
---
 drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 7 +++++++
 drivers/gpu/drm/i915/gt/intel_gtt.h  | 1 +
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c 
b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
index 84aa29715e0ac..6344d733fb2c4 100644
--- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
@@ -230,6 +230,7 @@ static void gen8_ppgtt_cleanup(struct i915_address_space 
*vm)
                                     gen8_pd_top_count(vm), vm->top);
 
        free_scratch(vm);
+       drm_mm_remove_node(&vm->rsvd);
 }
 
 static u64 __gen8_ppgtt_clear(struct i915_address_space * const vm,
@@ -1014,6 +1015,12 @@ struct i915_ppgtt *gen8_ppgtt_create(struct intel_gt *gt,
        ppgtt->vm.foreach = gen8_ppgtt_foreach;
        ppgtt->vm.cleanup = gen8_ppgtt_cleanup;
 
+       ppgtt->vm.rsvd.start = ppgtt->vm.total - (SZ_4K * 2);
+       ppgtt->vm.rsvd.size = (SZ_4K * 2);
+       ppgtt->vm.rsvd.color = I915_COLOR_UNEVICTABLE;
+       GEM_BUG_ON(drm_mm_reserve_node(&ppgtt->vm.mm, &ppgtt->vm.rsvd));
+       ppgtt->vm.total -= (SZ_4K * 2);
+
        err = gen8_init_scratch(&ppgtt->vm);
        if (err)
                goto err_put;
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h 
b/drivers/gpu/drm/i915/gt/intel_gtt.h
index 153ddfca0ae18..680ce27dda40c 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
@@ -247,6 +247,7 @@ struct i915_address_space {
        struct work_struct release_work;
 
        struct drm_mm mm;
+       struct drm_mm_node rsvd;
        struct intel_gt *gt;
        struct drm_i915_private *i915;
        struct device *dma;
-- 
2.25.1