Reviewed the patch & it looks fine.
Reviewed-by: "Akash Goel <akash.g...@intel.com>"


On 8/3/2015 2:22 PM, Michel Thierry wrote:
Introduces the Page Map Level 4 (PML4), ie. the new top level structure
of the page tables.

To facilitate testing, 48b mode will be available on Broadwell and
GEN9+, when i915.enable_ppgtt = 3.

v2: Remove unnecessary CONFIG_X86_64 checks, ppgtt code is already
32/64-bit safe (Chris).
v3: Add goto free_scratch in temp 48-bit mode init code (Akash).
v4: kfree the pdp until the 4lvl alloc/free patch (Akash).
v5: Postpone 48-bit code in sanitize_enable_ppgtt (Akash).
v6: Keep _insert_pte_entries changes outside this patch (Akash).

Cc: Akash Goel <akash.g...@intel.com>
Signed-off-by: Michel Thierry <michel.thie...@intel.com>
---
  drivers/gpu/drm/i915/i915_drv.h     |  3 ++-
  drivers/gpu/drm/i915/i915_gem_gtt.c | 27 +++++++++++++++++----------
  drivers/gpu/drm/i915/i915_gem_gtt.h | 26 +++++++++++++++++++++-----
  3 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 04aa34a..4729eaf 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2498,7 +2498,8 @@ struct drm_i915_cmd_table {
  #define HAS_HW_CONTEXTS(dev)  (INTEL_INFO(dev)->gen >= 6)
  #define HAS_LOGICAL_RING_CONTEXTS(dev)        (INTEL_INFO(dev)->gen >= 8)
  #define USES_PPGTT(dev)               (i915.enable_ppgtt)
-#define USES_FULL_PPGTT(dev)   (i915.enable_ppgtt == 2)
+#define USES_FULL_PPGTT(dev)   (i915.enable_ppgtt >= 2)
+#define USES_FULL_48BIT_PPGTT(dev)     (i915.enable_ppgtt == 3)

  #define HAS_OVERLAY(dev)              (INTEL_INFO(dev)->has_overlay)
  #define OVERLAY_NEEDS_PHYSICAL(dev)   
(INTEL_INFO(dev)->overlay_needs_physical)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c 
b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 7f71746..e099c18 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1105,14 +1105,6 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
                return ret;

        ppgtt->base.start = 0;
-       ppgtt->base.total = 1ULL << 32;
-       if (IS_ENABLED(CONFIG_X86_32))
-               /* While we have a proliferation of size_t variables
-                * we cannot represent the full ppgtt size on 32bit,
-                * so limit it to the same size as the GGTT (currently
-                * 2GiB).
-                */
-               ppgtt->base.total = to_i915(ppgtt->base.dev)->gtt.base.total;
        ppgtt->base.cleanup = gen8_ppgtt_cleanup;
        ppgtt->base.allocate_va_range = gen8_alloc_va_range;
        ppgtt->base.insert_entries = gen8_ppgtt_insert_entries;
@@ -1122,10 +1114,25 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)

        ppgtt->switch_mm = gen8_mm_switch;

-       ret = __pdp_init(false, &ppgtt->pdp);
+       if (!USES_FULL_48BIT_PPGTT(ppgtt->base.dev)) {
+               ret = __pdp_init(false, &ppgtt->pdp);

-       if (ret)
+               if (ret)
+                       goto free_scratch;
+
+               ppgtt->base.total = 1ULL << 32;
+               if (IS_ENABLED(CONFIG_X86_32))
+                       /* While we have a proliferation of size_t variables
+                        * we cannot represent the full ppgtt size on 32bit,
+                        * so limit it to the same size as the GGTT (currently
+                        * 2GiB).
+                        */
+                       ppgtt->base.total = 
to_i915(ppgtt->base.dev)->gtt.base.total;
+       } else {
+               ppgtt->base.total = 1ULL << 48;
+               ret = -EPERM; /* Not yet implemented */
                goto free_scratch;
+       }

        return 0;

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h 
b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 87e389c..04bc66f 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -88,9 +88,17 @@ typedef uint64_t gen8_pde_t;
   * PDPE  |  PDE  |  PTE  | offset
   * The difference as compared to normal x86 3 level page table is the PDPEs 
are
   * programmed via register.
+ *
+ * GEN8 48b legacy style address is defined as a 4 level page table:
+ * 47:39 | 38:30 | 29:21 | 20:12 |  11:0
+ * PML4E | PDPE  |  PDE  |  PTE  | offset
   */
+#define GEN8_PML4ES_PER_PML4           512
+#define GEN8_PML4E_SHIFT               39
  #define GEN8_PDPE_SHIFT                       30
-#define GEN8_PDPE_MASK                 0x3
+/* NB: GEN8_PDPE_MASK is untrue for 32b platforms, but it has no impact on 32b 
page
+ * tables */
+#define GEN8_PDPE_MASK                 0x1ff
  #define GEN8_PDE_SHIFT                        21
  #define GEN8_PDE_MASK                 0x1ff
  #define GEN8_PTE_SHIFT                        12
@@ -98,8 +106,8 @@ typedef uint64_t gen8_pde_t;
  #define GEN8_LEGACY_PDPES             4
  #define GEN8_PTES                     I915_PTES(sizeof(gen8_pte_t))

-/* FIXME: Next patch will use dev */
-#define I915_PDPES_PER_PDP(dev)                GEN8_LEGACY_PDPES
+#define I915_PDPES_PER_PDP(dev) (USES_FULL_48BIT_PPGTT(dev) ?\
+                                GEN8_PML4ES_PER_PML4 : GEN8_LEGACY_PDPES)

  #define PPAT_UNCACHED_INDEX           (_PAGE_PWT | _PAGE_PCD)
  #define PPAT_CACHED_PDE_INDEX         0 /* WB LLC */
@@ -250,6 +258,13 @@ struct i915_page_directory_pointer {
        struct i915_page_directory **page_directory;
  };

+struct i915_pml4 {
+       struct i915_page_dma base;
+
+       DECLARE_BITMAP(used_pml4es, GEN8_PML4ES_PER_PML4);
+       struct i915_page_directory_pointer *pdps[GEN8_PML4ES_PER_PML4];
+};
+
  struct i915_address_space {
        struct drm_mm mm;
        struct drm_device *dev;
@@ -345,8 +360,9 @@ struct i915_hw_ppgtt {
        struct drm_mm_node node;
        unsigned long pd_dirty_rings;
        union {
-               struct i915_page_directory_pointer pdp;
-               struct i915_page_directory pd;
+               struct i915_pml4 pml4;          /* GEN8+ & 48b PPGTT */
+               struct i915_page_directory_pointer pdp; /* GEN8+ */
+               struct i915_page_directory pd;          /* GEN6-7 */
        };

        struct drm_i915_file_private *file_priv;

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