On 7/1/2015 8:57 PM, Michel Thierry wrote:
This transitional patch doesn't do much for the existing code. However,
it should make upcoming patches to use the full 48b address space a bit
easier. The patch also introduces the PML4, ie. the new top level structure
of the page tables.


Would be better to move the introduction of PML4 to a separate patch & keep this patch only for the dynamic allocation of pdp changes.

v2: Renamed  pdp_free to be similar to  pd/pt (unmap_and_free_pdp).
v3: To facilitate testing, 48b mode will be available on Broadwell and
GEN9+, when i915.enable_ppgtt = 3.
v4: Rebase after s/page_tables/page_table/, added extra information
about 4-level page table formats and use IS_ENABLED macro.
v5: Check CONFIG_X86_64 instead of CONFIG_64BIT.
v6: Rebase after Mika's ppgtt cleanup / scratch merge patch series, and follow
his nomenclature in pdp functions (there is no alloc_pdp yet).
v7: Rebase after merged version of Mika's ppgtt cleanup patch series.
v8: Rebase after final merged version of Mika's ppgtt/scratch patches.

Signed-off-by: Ben Widawsky <b...@bwidawsk.net>
Signed-off-by: Michel Thierry <michel.thie...@intel.com> (v2+)
---
  drivers/gpu/drm/i915/i915_drv.h     |   7 ++-
  drivers/gpu/drm/i915/i915_gem_gtt.c | 116 ++++++++++++++++++++++++++++--------
  drivers/gpu/drm/i915/i915_gem_gtt.h |  41 ++++++++++---
  3 files changed, 128 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 1dbd957..7bccfd5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2490,7 +2490,12 @@ 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)
+#ifdef CONFIG_X86_64
+# define USES_FULL_48BIT_PPGTT(dev)    (i915.enable_ppgtt == 3)
+#else
+# define USES_FULL_48BIT_PPGTT(dev)    false
+#endif

  #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 712ca34..cdcc778 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -104,9 +104,13 @@ static int sanitize_enable_ppgtt(struct drm_device *dev, 
int enable_ppgtt)
  {
        bool has_aliasing_ppgtt;
        bool has_full_ppgtt;
+       bool has_full_64bit_ppgtt;

        has_aliasing_ppgtt = INTEL_INFO(dev)->gen >= 6;
        has_full_ppgtt = INTEL_INFO(dev)->gen >= 7;
+       has_full_64bit_ppgtt = IS_ENABLED(CONFIG_X86_64) &&
+                              (IS_BROADWELL(dev) ||
+                               INTEL_INFO(dev)->gen >= 9) && false; /* FIXME: 
64b */

        if (intel_vgpu_active(dev))
                has_full_ppgtt = false; /* emulation is too hard */
@@ -125,6 +129,9 @@ static int sanitize_enable_ppgtt(struct drm_device *dev, 
int enable_ppgtt)
        if (enable_ppgtt == 2 && has_full_ppgtt)
                return 2;

+       if (enable_ppgtt == 3 && has_full_64bit_ppgtt)
+               return 3;
+
  #ifdef CONFIG_INTEL_IOMMU
        /* Disable ppgtt on SNB if VT-d is on. */
        if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped) {
@@ -522,6 +529,45 @@ static void gen8_initialize_pd(struct i915_address_space 
*vm,
        fill_px(vm->dev, pd, scratch_pde);
  }

+static int __pdp_init(struct drm_device *dev,
+                     struct i915_page_directory_pointer *pdp)
+{
+       size_t pdpes = I915_PDPES_PER_PDP(dev);
+
+       pdp->used_pdpes = kcalloc(BITS_TO_LONGS(pdpes),
+                                 sizeof(unsigned long),
+                                 GFP_KERNEL);
+       if (!pdp->used_pdpes)
+               return -ENOMEM;
+
+       pdp->page_directory = kcalloc(pdpes, sizeof(*pdp->page_directory),
+                                     GFP_KERNEL);
+       if (!pdp->page_directory) {
+               kfree(pdp->used_pdpes);
+               /* the PDP might be the statically allocated top level. Keep it
+                * as clean as possible */
+               pdp->used_pdpes = NULL;
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+static void __pdp_fini(struct i915_page_directory_pointer *pdp)
+{
+       kfree(pdp->used_pdpes);
+       kfree(pdp->page_directory);
+       pdp->page_directory = NULL;
+}
+
+static void free_pdp(struct drm_device *dev,
+                    struct i915_page_directory_pointer *pdp)
+{
+       __pdp_fini(pdp);
+       if (USES_FULL_48BIT_PPGTT(dev))
+               kfree(pdp);
+}
+
  /* Broadwell Page Directory Pointer Descriptors */
  static int gen8_write_pdp(struct drm_i915_gem_request *req,
                          unsigned entry,
@@ -634,9 +680,6 @@ static void gen8_ppgtt_insert_entries(struct 
i915_address_space *vm,
        pt_vaddr = NULL;

        for_each_sg_page(pages->sgl, &sg_iter, pages->nents, 0) {
-               if (WARN_ON(pdpe >= GEN8_LEGACY_PDPES))
-                       break;
-
                if (pt_vaddr == NULL) {
                        struct i915_page_directory *pd = 
ppgtt->pdp.page_directory[pdpe];
                        struct i915_page_table *pt = pd->page_table[pde];
@@ -720,7 +763,8 @@ static void gen8_ppgtt_cleanup(struct i915_address_space 
*vm)
                container_of(vm, struct i915_hw_ppgtt, base);
        int i;

-       for_each_set_bit(i, ppgtt->pdp.used_pdpes, GEN8_LEGACY_PDPES) {
+       for_each_set_bit(i, ppgtt->pdp.used_pdpes,
+                               I915_PDPES_PER_PDP(ppgtt->base.dev)) {
                if (WARN_ON(!ppgtt->pdp.page_directory[i]))
                        continue;

@@ -729,6 +773,7 @@ static void gen8_ppgtt_cleanup(struct i915_address_space 
*vm)
                free_pd(ppgtt->base.dev, ppgtt->pdp.page_directory[i]);
        }

+       free_pdp(ppgtt->base.dev, &ppgtt->pdp);
        gen8_free_scratch(vm);
  }

@@ -820,8 +865,9 @@ static int gen8_ppgtt_alloc_page_directories(struct 
i915_hw_ppgtt *ppgtt,
        struct i915_page_directory *pd;
        uint64_t temp;
        uint32_t pdpe;
+       uint32_t pdpes =  I915_PDPES_PER_PDP(ppgtt->base.dev);

-       WARN_ON(!bitmap_empty(new_pds, GEN8_LEGACY_PDPES));
+       WARN_ON(!bitmap_empty(new_pds, pdpes));

        gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
                if (pd)
@@ -839,18 +885,19 @@ static int gen8_ppgtt_alloc_page_directories(struct 
i915_hw_ppgtt *ppgtt,
        return 0;

  unwind_out:
-       for_each_set_bit(pdpe, new_pds, GEN8_LEGACY_PDPES)
+       for_each_set_bit(pdpe, new_pds, pdpes)
                free_pd(dev, pdp->page_directory[pdpe]);

        return -ENOMEM;
  }

  static void
-free_gen8_temp_bitmaps(unsigned long *new_pds, unsigned long **new_pts)
+free_gen8_temp_bitmaps(unsigned long *new_pds, unsigned long **new_pts,
+                      uint32_t pdpes)
  {
        int i;

-       for (i = 0; i < GEN8_LEGACY_PDPES; i++)
+       for (i = 0; i < pdpes; i++)
                kfree(new_pts[i]);
        kfree(new_pts);
        kfree(new_pds);
@@ -861,23 +908,24 @@ free_gen8_temp_bitmaps(unsigned long *new_pds, unsigned 
long **new_pts)
   */
  static
  int __must_check alloc_gen8_temp_bitmaps(unsigned long **new_pds,
-                                        unsigned long ***new_pts)
+                                        unsigned long ***new_pts,
+                                        uint32_t pdpes)
  {
        int i;
        unsigned long *pds;
        unsigned long **pts;

-       pds = kcalloc(BITS_TO_LONGS(GEN8_LEGACY_PDPES), sizeof(unsigned long), 
GFP_KERNEL);
+       pds = kcalloc(BITS_TO_LONGS(pdpes), sizeof(unsigned long), GFP_KERNEL);
        if (!pds)
                return -ENOMEM;

-       pts = kcalloc(GEN8_LEGACY_PDPES, sizeof(unsigned long *), GFP_KERNEL);
+       pts = kcalloc(pdpes, sizeof(unsigned long *), GFP_KERNEL);
        if (!pts) {
                kfree(pds);
                return -ENOMEM;
        }

-       for (i = 0; i < GEN8_LEGACY_PDPES; i++) {
+       for (i = 0; i < pdpes; i++) {
                pts[i] = kcalloc(BITS_TO_LONGS(I915_PDES),
                                 sizeof(unsigned long), GFP_KERNEL);
                if (!pts[i])
@@ -890,7 +938,7 @@ int __must_check alloc_gen8_temp_bitmaps(unsigned long 
**new_pds,
        return 0;

  err_out:
-       free_gen8_temp_bitmaps(pds, pts);
+       free_gen8_temp_bitmaps(pds, pts, pdpes);
        return -ENOMEM;
  }

@@ -916,6 +964,7 @@ static int gen8_alloc_va_range(struct i915_address_space 
*vm,
        const uint64_t orig_length = length;
        uint64_t temp;
        uint32_t pdpe;
+       uint32_t pdpes = I915_PDPES_PER_PDP(dev);
        int ret;

        /* Wrap is never okay since we can only represent 48b, and we don't
@@ -927,7 +976,7 @@ static int gen8_alloc_va_range(struct i915_address_space 
*vm,
        if (WARN_ON(start + length > ppgtt->base.total))
                return -ENODEV;

-       ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables);
+       ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables, pdpes);
        if (ret)
                return ret;

@@ -935,7 +984,7 @@ static int gen8_alloc_va_range(struct i915_address_space 
*vm,
        ret = gen8_ppgtt_alloc_page_directories(ppgtt, &ppgtt->pdp, start, 
length,
                                        new_page_dirs);
        if (ret) {
-               free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);
+               free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes);
                return ret;
        }

@@ -989,7 +1038,7 @@ static int gen8_alloc_va_range(struct i915_address_space 
*vm,
                __set_bit(pdpe, ppgtt->pdp.used_pdpes);
        }

-       free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);
+       free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes);
        mark_tlbs_dirty(ppgtt);
        return 0;

@@ -999,10 +1048,10 @@ err_out:
                        free_pt(vm->dev, 
ppgtt->pdp.page_directory[pdpe]->page_table[temp]);
        }

-       for_each_set_bit(pdpe, new_page_dirs, GEN8_LEGACY_PDPES)
+       for_each_set_bit(pdpe, new_page_dirs, pdpes)
                free_pd(vm->dev, ppgtt->pdp.page_directory[pdpe]);

-       free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);
+       free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes);
        mark_tlbs_dirty(ppgtt);
        return ret;
  }
@@ -1023,14 +1072,6 @@ 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;
@@ -1040,7 +1081,30 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)

        ppgtt->switch_mm = gen8_mm_switch;

+       if (!USES_FULL_48BIT_PPGTT(ppgtt->base.dev)) {
+               ret = __pdp_init(false, &ppgtt->pdp);
+
+               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;
+               return -EPERM; /* Not yet implemented */
+       }
+
        return 0;
+
+free_scratch:
+       gen8_free_scratch(&ppgtt->base);
+       return ret;
  }

  static void gen6_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h 
b/drivers/gpu/drm/i915/i915_gem_gtt.h
index d5bf953..e2b684e 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
@@ -98,6 +106,9 @@ typedef uint64_t gen8_pde_t;
  #define GEN8_LEGACY_PDPES             4
  #define GEN8_PTES                     I915_PTES(sizeof(gen8_pte_t))

+#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 */
  #define PPAT_CACHED_INDEX             _PAGE_PAT /* WB LLCeLLC */
@@ -241,9 +252,17 @@ struct i915_page_directory {
  };

  struct i915_page_directory_pointer {
-       /* struct page *page; */
-       DECLARE_BITMAP(used_pdpes, GEN8_LEGACY_PDPES);
-       struct i915_page_directory *page_directory[GEN8_LEGACY_PDPES];
+       struct i915_page_dma base;
+
+       unsigned long *used_pdpes;
+       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 {
@@ -341,8 +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;
@@ -436,14 +456,17 @@ static inline uint32_t gen6_pde_index(uint32_t addr)
             temp = min(temp, length),                                  \
             start += temp, length -= temp)

-#define gen8_for_each_pdpe(pd, pdp, start, length, temp, iter)         \
-       for (iter = gen8_pdpe_index(start);     \
-            pd = (pdp)->page_directory[iter], length > 0 && iter < 
GEN8_LEGACY_PDPES; \
+#define gen8_for_each_pdpe_e(pd, pdp, start, length, temp, iter, b)    \
+       for (iter = gen8_pdpe_index(start); \
+            pd = (pdp)->page_directory[iter], length > 0 && (iter < b);       \
             iter++,                            \
             temp = ALIGN(start+1, 1 << GEN8_PDPE_SHIFT) - start, \
             temp = min(temp, length),                                  \
             start += temp, length -= temp)

+#define gen8_for_each_pdpe(pd, pdp, start, length, temp, iter)         \
+       gen8_for_each_pdpe_e(pd, pdp, start, length, temp, iter, 
I915_PDPES_PER_PDP(dev))
+
  static inline uint32_t gen8_pte_index(uint64_t address)
  {
        return i915_pte_index(address, GEN8_PDE_SHIFT);

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