Re: [PATCH 02/12] drm/i915/bdw: Abstract PDP usage

[Michel Thierry <michel.thierry@intel.com>]

On 3/3/2015 12:16 PM, akash goel wrote:
> On Fri, Feb 20, 2015 at 11:15 PM, Michel Thierry
> <michel.thierry@intel.com>  wrote:
>> From: Ben Widawsky<benjamin.widawsky@intel.com>
>>
>> Up until now, ppgtt->pdp has always been the root of our page tables.
>> Legacy 32b addresses acted like it had 1 PDP with 4 PDPEs.
>>
>> In preparation for 4 level page tables, we need to stop use ppgtt->pdp
>> directly unless we know it's what we want. The future structure will use
>> ppgtt->pml4 for the top level, and the pdp is just one of the entries
>> being pointed to by a pml4e.
>>
>> v2: Updated after dynamic page allocation changes.
>>
>> Signed-off-by: Ben Widawsky<ben@bwidawsk.net>
>> Signed-off-by: Michel Thierry<michel.thierry@intel.com>  (v2)
>> ---
>>   drivers/gpu/drm/i915/i915_gem_gtt.c | 123 ++++++++++++++++++++----------------
>>   1 file changed, 70 insertions(+), 53 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> index 489f8db..d3ad517 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
>> @@ -560,6 +560,7 @@ static void gen8_ppgtt_clear_range(struct i915_address_space *vm,
>>   {
>>          struct i915_hw_ppgtt *ppgtt =
>>                  container_of(vm, struct i915_hw_ppgtt, base);
>> +       struct i915_page_directory_pointer_entry *pdp = &ppgtt->pdp; /* FIXME: 48b */
>>          gen8_gtt_pte_t *pt_vaddr, scratch_pte;
>>          unsigned pdpe = start >> GEN8_PDPE_SHIFT & GEN8_PDPE_MASK;
>>          unsigned pde = start >> GEN8_PDE_SHIFT & GEN8_PDE_MASK;
>> @@ -575,10 +576,10 @@ static void gen8_ppgtt_clear_range(struct i915_address_space *vm,
>>                  struct i915_page_table_entry *pt;
>>                  struct page *page_table;
>>
>> -               if (WARN_ON(!ppgtt->pdp.page_directory[pdpe]))
>> +               if (WARN_ON(!pdp->page_directory[pdpe]))
>>                          continue;
>>
>> -               pd = ppgtt->pdp.page_directory[pdpe];
>> +               pd = pdp->page_directory[pdpe];
>>
>>                  if (WARN_ON(!pd->page_tables[pde]))
>>                          continue;
>> @@ -620,6 +621,7 @@ static void gen8_ppgtt_insert_entries(struct i915_address_space *vm,
>>   {
>>          struct i915_hw_ppgtt *ppgtt =
>>                  container_of(vm, struct i915_hw_ppgtt, base);
>> +       struct i915_page_directory_pointer_entry *pdp = &ppgtt->pdp; /* FIXME: 48b */
>>          gen8_gtt_pte_t *pt_vaddr;
>>          unsigned pdpe = start >> GEN8_PDPE_SHIFT & GEN8_PDPE_MASK;
>>          unsigned pde = start >> GEN8_PDE_SHIFT & GEN8_PDE_MASK;
>> @@ -630,7 +632,7 @@ static void gen8_ppgtt_insert_entries(struct i915_address_space *vm,
>>
>>          for_each_sg_page(pages->sgl, &sg_iter, pages->nents, 0) {
>>                  if (pt_vaddr == NULL) {
>> -                       struct i915_page_directory_entry *pd = ppgtt->pdp.page_directory[pdpe];
>> +                       struct i915_page_directory_entry *pd = pdp->page_directory[pdpe];
>>                          struct i915_page_table_entry *pt = pd->page_tables[pde];
>>                          struct page *page_table = pt->page;
>>
>> @@ -708,16 +710,17 @@ static void gen8_free_page_tables(struct i915_page_directory_entry *pd, struct d
>>   static void gen8_ppgtt_unmap_pages(struct i915_hw_ppgtt *ppgtt)
>>   {
>>          struct pci_dev *hwdev = ppgtt->base.dev->pdev;
>> +       struct i915_page_directory_pointer_entry *pdp = &ppgtt->pdp; /* FIXME: 48b */
>>          int i, j;
>>
>> -       for_each_set_bit(i, ppgtt->pdp.used_pdpes,
>> +       for_each_set_bit(i, pdp->used_pdpes,
>>                          I915_PDPES_PER_PDP(ppgtt->base.dev)) {
>>                  struct i915_page_directory_entry *pd;
>>
>> -               if (WARN_ON(!ppgtt->pdp.page_directory[i]))
>> +               if (WARN_ON(!pdp->page_directory[i]))
>>                          continue;
>>
>> -               pd = ppgtt->pdp.page_directory[i];
>> +               pd = pdp->page_directory[i];
>>                  if (!pd->daddr)
>>                          pci_unmap_page(hwdev, pd->daddr, PAGE_SIZE,
>>                                          PCI_DMA_BIDIRECTIONAL);
>> @@ -743,15 +746,21 @@ static void gen8_ppgtt_free(struct i915_hw_ppgtt *ppgtt)
>>   {
>>          int i;
>>
>> -       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;
>> +       if (!USES_FULL_48BIT_PPGTT(ppgtt->base.dev)) {
>> +               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;
>>
>> -               gen8_free_page_tables(ppgtt->pdp.page_directory[i], ppgtt->base.dev);
>> -               unmap_and_free_pd(ppgtt->pdp.page_directory[i], ppgtt->base.dev);
>> +                       gen8_free_page_tables(ppgtt->pdp.page_directory[i],
>> +                                             ppgtt->base.dev);
>> +                       unmap_and_free_pd(ppgtt->pdp.page_directory[i],
>> +                                         ppgtt->base.dev);
>> +               }
>> +               unmap_and_free_pdp(&ppgtt->pdp, ppgtt->base.dev);
>> +       } else {
>> +               BUG(); /* to be implemented later */
>>          }
>> -       unmap_and_free_pdp(&ppgtt->pdp, ppgtt->base.dev);
>>   }
>>
>>   static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
>> @@ -765,7 +774,7 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
>>
>>   /**
>>    * gen8_ppgtt_alloc_pagetabs() - Allocate page tables for VA range.
>> - * @ppgtt:     Master ppgtt structure.
>> + * @vm:                Master vm structure.
>>    * @pd:                Page directory for this address range.
>>    * @start:     Starting virtual address to begin allocations.
>>    * @length     Size of the allocations.
>> @@ -781,12 +790,13 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
>>    *
>>    * Return: 0 if success; negative error code otherwise.
>>    */
>> -static int gen8_ppgtt_alloc_pagetabs(struct i915_hw_ppgtt *ppgtt,
>> +static int gen8_ppgtt_alloc_pagetabs(struct i915_address_space *vm,
>>                                       struct i915_page_directory_entry *pd,
>>                                       uint64_t start,
>>                                       uint64_t length,
>>                                       unsigned long *new_pts)
>>   {
>> +       struct drm_device *dev = vm->dev;
>>          struct i915_page_table_entry *pt;
>>          uint64_t temp;
>>          uint32_t pde;
>> @@ -799,7 +809,7 @@ static int gen8_ppgtt_alloc_pagetabs(struct i915_hw_ppgtt *ppgtt,
>>                          continue;
>>                  }
>>
>> -               pt = alloc_pt_single(ppgtt->base.dev);
>> +               pt = alloc_pt_single(dev);
>>                  if (IS_ERR(pt))
>>                          goto unwind_out;
>>
>> @@ -811,14 +821,14 @@ static int gen8_ppgtt_alloc_pagetabs(struct i915_hw_ppgtt *ppgtt,
>>
>>   unwind_out:
>>          for_each_set_bit(pde, new_pts, GEN8_PDES_PER_PAGE)
>> -               unmap_and_free_pt(pd->page_tables[pde], ppgtt->base.dev);
>> +               unmap_and_free_pt(pd->page_tables[pde], dev);
>>
>>          return -ENOMEM;
>>   }
>>
>>   /**
>>    * gen8_ppgtt_alloc_page_directories() - Allocate page directories for VA range.
>> - * @ppgtt:     Master ppgtt structure.
>> + * @vm:                Master vm structure.
>>    * @pdp:       Page directory pointer for this address range.
>>    * @start:     Starting virtual address to begin allocations.
>>    * @length     Size of the allocations.
>> @@ -839,16 +849,17 @@ unwind_out:
>>    *
>>    * Return: 0 if success; negative error code otherwise.
>>    */
>> -static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
>> +static int gen8_ppgtt_alloc_page_directories(struct i915_address_space *vm,
>>                                       struct i915_page_directory_pointer_entry *pdp,
>>                                       uint64_t start,
>>                                       uint64_t length,
>>                                       unsigned long *new_pds)
>>   {
>> +       struct drm_device *dev = vm->dev;
>>          struct i915_page_directory_entry *pd;
>>          uint64_t temp;
>>          uint32_t pdpe;
>> -       size_t pdpes =  I915_PDPES_PER_PDP(ppgtt->base.dev);
>> +       size_t pdpes =  I915_PDPES_PER_PDP(vm->dev);
>>
>>          BUG_ON(!bitmap_empty(new_pds, pdpes));
>>
>> @@ -859,7 +870,7 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
>>                  if (pd)
>>                          continue;
>>
>> -               pd = alloc_pd_single(ppgtt->base.dev);
>> +               pd = alloc_pd_single(dev);
>>                  if (IS_ERR(pd))
>>                          goto unwind_out;
>>
>> @@ -871,7 +882,7 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
>>
>>   unwind_out:
>>          for_each_set_bit(pdpe, new_pds, pdpes)
>> -               unmap_and_free_pd(pdp->page_directory[pdpe], ppgtt->base.dev);
>> +               unmap_and_free_pd(pdp->page_directory[pdpe], dev);
>>
>>          return -ENOMEM;
>>   }
>> @@ -926,13 +937,13 @@ err_out:
>>          return -ENOMEM;
>>   }
>>
>> -static int gen8_alloc_va_range(struct i915_address_space *vm,
>> -                              uint64_t start,
>> -                              uint64_t length)
>> +static int gen8_alloc_va_range_3lvl(struct i915_address_space *vm,
>> +                                   struct i915_page_directory_pointer_entry *pdp,
>> +                                   uint64_t start,
>> +                                   uint64_t length)
>>   {
>> -       struct i915_hw_ppgtt *ppgtt =
>> -               container_of(vm, struct i915_hw_ppgtt, base);
>>          unsigned long *new_page_dirs, **new_page_tables;
>> +       struct drm_device *dev = vm->dev;
>>          struct i915_page_directory_entry *pd;
>>          const uint64_t orig_start = start;
>>          const uint64_t orig_length = length;
>> @@ -961,17 +972,15 @@ static int gen8_alloc_va_range(struct i915_address_space *vm,
>>                  return ret;
>>
>>          /* Do the allocations first so we can easily bail out */
>> -       ret = gen8_ppgtt_alloc_page_directories(ppgtt, &ppgtt->pdp, start, length,
>> -                                       new_page_dirs);
>> +       ret = gen8_ppgtt_alloc_page_directories(vm, pdp, start, length, new_page_dirs);
>>          if (ret) {
>>                  free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes);
>>                  return ret;
>>          }
>>
>> -       /* For every page directory referenced, allocate page tables */
>> -       gen8_for_each_pdpe(pd, &ppgtt->pdp, start, length, temp, pdpe) {
>> +       gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
>>                  bitmap_zero(new_page_tables[pdpe], GEN8_PDES_PER_PAGE);
>> -               ret = gen8_ppgtt_alloc_pagetabs(ppgtt, pd, start, length,
>> +               ret = gen8_ppgtt_alloc_pagetabs(vm, pd, start, length,
>>                                                  new_page_tables[pdpe]);
>>                  if (ret)
>>                          goto err_out;
>> @@ -980,10 +989,7 @@ static int gen8_alloc_va_range(struct i915_address_space *vm,
>>          start = orig_start;
>>          length = orig_length;
>>
>> -       /* Allocations have completed successfully, so set the bitmaps, and do
>> -        * the mappings. */
>> -       gen8_for_each_pdpe(pd, &ppgtt->pdp, start, length, temp, pdpe) {
>> -               gen8_ppgtt_pde_t *const page_directory = kmap_atomic(pd->page);
>> +       gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
>>                  struct i915_page_table_entry *pt;
>>                  uint64_t pd_len = gen8_clamp_pd(start, length);
>>                  uint64_t pd_start = start;
>> @@ -1005,20 +1011,10 @@ static int gen8_alloc_va_range(struct i915_address_space *vm,
>>
>>                          /* Our pde is now pointing to the pagetable, pt */
>>                          set_bit(pde, pd->used_pdes);
>> -
>> -                       /* Map the PDE to the page table */
>> -                       __gen8_do_map_pt(page_directory + pde, pt, vm->dev);
>> -
>> -                       /* NB: We haven't yet mapped ptes to pages. At this
>> -                        * point we're still relying on insert_entries() */
>>                  }
>>
>> -               if (!HAS_LLC(vm->dev))
>> -                       drm_clflush_virt_range(page_directory, PAGE_SIZE);
>> -
>> -               kunmap_atomic(page_directory);
>> -
>> -               set_bit(pdpe, ppgtt->pdp.used_pdpes);
>> +               set_bit(pdpe, pdp->used_pdpes);
>> +               gen8_map_pagetable_range(pd, start, length, dev);
>>          }
>>
>>          free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes);
>> @@ -1027,16 +1023,36 @@ static int gen8_alloc_va_range(struct i915_address_space *vm,
>>   err_out:
>>          while (pdpe--) {
>>                  for_each_set_bit(temp, new_page_tables[pdpe], GEN8_PDES_PER_PAGE)
>> -                       unmap_and_free_pt(pd->page_tables[temp], vm->dev);
>> +                       unmap_and_free_pt(pd->page_tables[temp], dev);
> Sorry the review comment may not be completely pertinent to this very patch.
> In the while loop, on the change of 'pdpe' value, the 'pd' is not
> being updated accordingly.
> The above call to 'unmap_and_free_pt(pd->page_table[temp], dev);'
> should be replaced with
>      'unmap_and_free_pt(pdp->page_directory[pdpe]->page_table[temp], dev);'
> This will give the right page directory.
Fixed in the patch that brings this code (drm/i915/bdw: Dynamic page 
table allocations).

>>          }
>>
>>          for_each_set_bit(pdpe, new_page_dirs, pdpes)
>> -               unmap_and_free_pd(ppgtt->pdp.page_directory[pdpe], vm->dev);
>> +               unmap_and_free_pd(pdp->page_directory[pdpe], dev);
>>
>>          free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes);
>>          return ret;
>>   }
>>
>> +static int __noreturn gen8_alloc_va_range_4lvl(struct i915_address_space *vm,
>> +                                              struct i915_pml4 *pml4,
>> +                                              uint64_t start,
>> +                                              uint64_t length)
>> +{
>> +       BUG(); /* to be implemented later */
>> +}
>> +
>> +static int gen8_alloc_va_range(struct i915_address_space *vm,
>> +                              uint64_t start, uint64_t length)
>> +{
>> +       struct i915_hw_ppgtt *ppgtt =
>> +               container_of(vm, struct i915_hw_ppgtt, base);
>> +
>> +       if (!USES_FULL_48BIT_PPGTT(vm->dev))
>> +               return gen8_alloc_va_range_3lvl(vm, &ppgtt->pdp, start, length);
>> +       else
>> +               return gen8_alloc_va_range_4lvl(vm, &ppgtt->pml4, start, length);
>> +}
>> +
>>   static void gen8_ppgtt_fini_common(struct i915_hw_ppgtt *ppgtt)
>>   {
>>          unmap_and_free_pt(ppgtt->scratch_pd, ppgtt->base.dev);
>> @@ -1079,12 +1095,13 @@ static int gen8_aliasing_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
>>   {
>>          struct drm_device *dev = ppgtt->base.dev;
>>          struct drm_i915_private *dev_priv = dev->dev_private;
>> +       struct i915_page_directory_pointer_entry *pdp = &ppgtt->pdp; /* FIXME: 48b */
>>          struct i915_page_directory_entry *pd;
>>          uint64_t temp, start = 0, size = dev_priv->gtt.base.total;
>>          uint32_t pdpe;
>>          int ret;
>>
>> -       ret = gen8_ppgtt_init_common(ppgtt, dev_priv->gtt.base.total);
>> +       ret = gen8_ppgtt_init_common(ppgtt, size);
>>          if (ret)
>>                  return ret;
>>
>> @@ -1097,8 +1114,8 @@ static int gen8_aliasing_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
>>                  return ret;
>>          }
>>
>> -       gen8_for_each_pdpe(pd, &ppgtt->pdp, start, size, temp, pdpe)
>> -               gen8_map_pagetable_range(pd, start, size, ppgtt->base.dev);
>> +       gen8_for_each_pdpe(pd, pdp, start, size, temp, pdpe)
>> +               gen8_map_pagetable_range(pd, start, size, dev);
> Sorry, again this comment may not be relevant for this patch.
> Is the explicit call to map the page of page tables really needed here ?
> As prior to this, already there is a call to gen8_alloc_va_range,
> which will map the page of page tables into the pdes, for the entire
> virtual range.
Thanks, it was a left over from a previous rebase (before aliasing and 
full ppgtt inits split). As you say it isn't needed.
Fixed in same patch as your prev comment (drm/i915/bdw: Dynamic page 
table allocations).

>>          ppgtt->base.allocate_va_range = NULL;
>>          ppgtt->base.clear_range = gen8_ppgtt_clear_range;
>> --
>> 2.1.1
>>
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