From cc7e02e04be03312c70937dfaec4f5219fb7a7b5 Mon Sep 17 00:00:00 2001
From: Matthew Auld <matthew.auld@intel.com>
Date: Fri, 25 Jun 2021 11:38:24 +0100
Subject: drm/i915/gtt: ignore min_page_size for paging structures
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Git-commit: 32334c9b1fd78ad661582c55b15d263a5d6d157d
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
The min_page_size is only needed for pages inserted into the GTT, and
for our paging structures we only need at most 4K bytes, so simply
ignore the min_page_size restrictions here, otherwise we might see some
severe overallocation on some devices.
v2(Thomas): add some commentary
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210625103824.558481-2-matthew.auld@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gt/intel_gtt.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
index 084ea65d59c0..f7e0352edb62 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
@@ -16,7 +16,19 @@ struct drm_i915_gem_object *alloc_pt_lmem(struct i915_address_space *vm, int sz)
{
struct drm_i915_gem_object *obj;
- obj = i915_gem_object_create_lmem(vm->i915, sz, 0);
+ /*
+ * To avoid severe over-allocation when dealing with min_page_size
+ * restrictions, we override that behaviour here by allowing an object
+ * size and page layout which can be smaller. In practice this should be
+ * totally fine, since GTT paging structures are not typically inserted
+ * into the GTT.
+ *
+ * Note that we also hit this path for the scratch page, and for this
+ * case it might need to be 64K, but that should work fine here since we
+ * used the passed in size for the page size, which should ensure it
+ * also has the same alignment.
+ */
+ obj = __i915_gem_object_create_lmem_with_ps(vm->i915, sz, sz, 0);
/*
* Ensure all paging structures for this vm share the same dma-resv
* object underneath, with the idea that one object_lock() will lock
--
2.38.1