drm/i915: Micro-optimise gen8_ppgtt_insert_entries()
authorChris Wilson <chris@chris-wilson.co.uk>
Wed, 15 Feb 2017 08:43:37 +0000 (08:43 +0000)
committerChris Wilson <chris@chris-wilson.co.uk>
Wed, 15 Feb 2017 10:05:53 +0000 (10:05 +0000)
Improve the sg iteration and in hte process eliminate a bug in
miscomputing the pml4 length as orig_nents<<PAGE_SHIFT is no longer the
full length of the sg table.

v2: Check for the end of the fourth level page table (the final pdpe)
and move onto the next.
v3: Assert that 3lvl insert_pte_entries doesn't overflow its smaller set
of PDP.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170215084357.19977-3-chris@chris-wilson.co.uk
drivers/gpu/drm/i915/i915_gem_gtt.c

index b33ff11c134573a47829de63834a2684d96695fc..f40f9365782f755e195f5a35b2a5a478e5dfa17b 100644 (file)
@@ -750,9 +750,9 @@ static bool gen8_ppgtt_clear_pt(struct i915_address_space *vm,
        unsigned int num_entries = gen8_pte_count(start, length);
        unsigned int pte = gen8_pte_index(start);
        unsigned int pte_end = pte + num_entries;
-       gen8_pte_t *pt_vaddr;
-       gen8_pte_t scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
-                                                I915_CACHE_LLC);
+       const gen8_pte_t scratch_pte =
+               gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC);
+       gen8_pte_t *vaddr;
 
        if (WARN_ON(!px_page(pt)))
                return false;
@@ -765,12 +765,10 @@ static bool gen8_ppgtt_clear_pt(struct i915_address_space *vm,
                        return true;
        }
 
-       pt_vaddr = kmap_px(pt);
-
+       vaddr = kmap_px(pt);
        while (pte < pte_end)
-               pt_vaddr[pte++] = scratch_pte;
-
-       kunmap_px(ppgtt, pt_vaddr);
+               vaddr[pte++] = scratch_pte;
+       kunmap_px(ppgtt, vaddr);
 
        return false;
 }
@@ -878,71 +876,100 @@ static void gen8_ppgtt_clear_range(struct i915_address_space *vm,
                gen8_ppgtt_clear_pdp(vm, &ppgtt->pdp, start, length);
 }
 
-static void
-gen8_ppgtt_insert_pte_entries(struct i915_address_space *vm,
+struct sgt_dma {
+       struct scatterlist *sg;
+       dma_addr_t dma, max;
+};
+
+static __always_inline bool
+gen8_ppgtt_insert_pte_entries(struct i915_hw_ppgtt *ppgtt,
                              struct i915_page_directory_pointer *pdp,
-                             struct sg_page_iter *sg_iter,
-                             uint64_t start,
+                             struct sgt_dma *iter,
+                             u64 start,
                              enum i915_cache_level cache_level)
 {
-       struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
-       gen8_pte_t *pt_vaddr;
-       unsigned pdpe = gen8_pdpe_index(start);
-       unsigned pde = gen8_pde_index(start);
-       unsigned pte = gen8_pte_index(start);
+       unsigned int pdpe = gen8_pdpe_index(start);
+       unsigned int pde = gen8_pde_index(start);
+       unsigned int pte = gen8_pte_index(start);
+       struct i915_page_directory *pd;
+       const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level);
+       gen8_pte_t *vaddr;
+       bool ret;
 
-       pt_vaddr = NULL;
+       pd = pdp->page_directory[pdpe];
+       vaddr = kmap_px(pd->page_table[pde]);
+       do {
+               vaddr[pte] = pte_encode | iter->dma;
+               iter->dma += PAGE_SIZE;
+               if (iter->dma >= iter->max) {
+                       iter->sg = __sg_next(iter->sg);
+                       if (!iter->sg) {
+                               ret = false;
+                               break;
+                       }
 
-       while (__sg_page_iter_next(sg_iter)) {
-               if (pt_vaddr == NULL) {
-                       struct i915_page_directory *pd = pdp->page_directory[pdpe];
-                       struct i915_page_table *pt = pd->page_table[pde];
-                       pt_vaddr = kmap_px(pt);
+                       iter->dma = sg_dma_address(iter->sg);
+                       iter->max = iter->dma + iter->sg->length;
                }
 
-               pt_vaddr[pte] =
-                       gen8_pte_encode(sg_page_iter_dma_address(sg_iter),
-                                       cache_level);
                if (++pte == GEN8_PTES) {
-                       kunmap_px(ppgtt, pt_vaddr);
-                       pt_vaddr = NULL;
                        if (++pde == I915_PDES) {
-                               if (++pdpe == I915_PDPES_PER_PDP(vm->i915))
+                               /* Limited by sg length for 3lvl */
+                               if (++pdpe == GEN8_PML4ES_PER_PML4) {
+                                       ret = true;
                                        break;
+                               }
+
+                               GEM_BUG_ON(pdpe > GEN8_LEGACY_PDPES);
+                               pd = pdp->page_directory[pdpe];
                                pde = 0;
                        }
+
+                       kunmap_px(ppgtt, vaddr);
+                       vaddr = kmap_px(pd->page_table[pde]);
                        pte = 0;
                }
-       }
+       } while (1);
+       kunmap_px(ppgtt, vaddr);
 
-       if (pt_vaddr)
-               kunmap_px(ppgtt, pt_vaddr);
+       return ret;
 }
 
-static void gen8_ppgtt_insert_entries(struct i915_address_space *vm,
-                                     struct sg_table *pages,
-                                     uint64_t start,
-                                     enum i915_cache_level cache_level,
-                                     u32 unused)
+static void gen8_ppgtt_insert_3lvl(struct i915_address_space *vm,
+                                  struct sg_table *pages,
+                                  u64 start,
+                                  enum i915_cache_level cache_level,
+                                  u32 unused)
 {
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
-       struct sg_page_iter sg_iter;
+       struct sgt_dma iter = {
+               .sg = pages->sgl,
+               .dma = sg_dma_address(iter.sg),
+               .max = iter.dma + iter.sg->length,
+       };
 
-       __sg_page_iter_start(&sg_iter, pages->sgl, sg_nents(pages->sgl), 0);
+       gen8_ppgtt_insert_pte_entries(ppgtt, &ppgtt->pdp, &iter,
+                                     start, cache_level);
+}
 
-       if (!USES_FULL_48BIT_PPGTT(vm->i915)) {
-               gen8_ppgtt_insert_pte_entries(vm, &ppgtt->pdp, &sg_iter, start,
-                                             cache_level);
-       } else {
-               struct i915_page_directory_pointer *pdp;
-               uint64_t pml4e;
-               uint64_t length = (uint64_t)pages->orig_nents << PAGE_SHIFT;
+static void gen8_ppgtt_insert_4lvl(struct i915_address_space *vm,
+                                  struct sg_table *pages,
+                                  uint64_t start,
+                                  enum i915_cache_level cache_level,
+                                  u32 unused)
+{
+       struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
+       struct sgt_dma iter = {
+               .sg = pages->sgl,
+               .dma = sg_dma_address(iter.sg),
+               .max = iter.dma + iter.sg->length,
+       };
+       struct i915_page_directory_pointer **pdps = ppgtt->pml4.pdps;
+       unsigned int pml4e = gen8_pml4e_index(start);
 
-               gen8_for_each_pml4e(pdp, &ppgtt->pml4, start, length, pml4e) {
-                       gen8_ppgtt_insert_pte_entries(vm, pdp, &sg_iter,
-                                                     start, cache_level);
-               }
-       }
+       while (gen8_ppgtt_insert_pte_entries(ppgtt, pdps[pml4e++], &iter,
+                                            start, cache_level))
+               ;
 }
 
 static void gen8_free_page_tables(struct drm_i915_private *dev_priv,
@@ -1524,8 +1551,8 @@ static void gen8_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m)
        struct i915_address_space *vm = &ppgtt->base;
        uint64_t start = ppgtt->base.start;
        uint64_t length = ppgtt->base.total;
-       gen8_pte_t scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
-                                                I915_CACHE_LLC);
+       const gen8_pte_t scratch_pte =
+               gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC);
 
        if (!USES_FULL_48BIT_PPGTT(vm->i915)) {
                gen8_dump_pdp(&ppgtt->pdp, start, length, scratch_pte, m);
@@ -1590,7 +1617,6 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
        ppgtt->base.start = 0;
        ppgtt->base.cleanup = gen8_ppgtt_cleanup;
        ppgtt->base.allocate_va_range = gen8_alloc_va_range;
-       ppgtt->base.insert_entries = gen8_ppgtt_insert_entries;
        ppgtt->base.clear_range = gen8_ppgtt_clear_range;
        ppgtt->base.unbind_vma = ppgtt_unbind_vma;
        ppgtt->base.bind_vma = ppgtt_bind_vma;
@@ -1605,6 +1631,8 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 
                ppgtt->base.total = 1ULL << 48;
                ppgtt->switch_mm = gen8_48b_mm_switch;
+
+               ppgtt->base.insert_entries = gen8_ppgtt_insert_4lvl;
        } else {
                ret = __pdp_init(dev_priv, &ppgtt->pdp);
                if (ret)
@@ -1621,6 +1649,8 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
                        if (ret)
                                goto free_scratch;
                }
+
+               ppgtt->base.insert_entries = gen8_ppgtt_insert_3lvl;
        }
 
        if (intel_vgpu_active(dev_priv))
@@ -1887,11 +1917,6 @@ static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
        }
 }
 
-struct sgt_dma {
-       struct scatterlist *sg;
-       dma_addr_t dma, max;
-};
-
 static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
                                      struct sg_table *pages,
                                      uint64_t start,
@@ -2433,26 +2458,15 @@ static void gen8_ggtt_insert_entries(struct i915_address_space *vm,
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        struct sgt_iter sgt_iter;
        gen8_pte_t __iomem *gtt_entries;
-       gen8_pte_t gtt_entry;
+       const gen8_pte_t pte_encode = gen8_pte_encode(0, level);
        dma_addr_t addr;
-       int i = 0;
 
-       gtt_entries = (gen8_pte_t __iomem *)ggtt->gsm + (start >> PAGE_SHIFT);
+       gtt_entries = (gen8_pte_t __iomem *)ggtt->gsm;
+       gtt_entries += start >> PAGE_SHIFT;
+       for_each_sgt_dma(addr, sgt_iter, st)
+               gen8_set_pte(gtt_entries++, pte_encode | addr);
 
-       for_each_sgt_dma(addr, sgt_iter, st) {
-               gtt_entry = gen8_pte_encode(addr, level);
-               gen8_set_pte(&gtt_entries[i++], gtt_entry);
-       }
-
-       /*
-        * XXX: This serves as a posting read to make sure that the PTE has
-        * actually been updated. There is some concern that even though
-        * registers and PTEs are within the same BAR that they are potentially
-        * of NUMA access patterns. Therefore, even with the way we assume
-        * hardware should work, we must keep this posting read for paranoia.
-        */
-       if (i != 0)
-               WARN_ON(readq(&gtt_entries[i-1]) != gtt_entry);
+       wmb();
 
        /* This next bit makes the above posting read even more important. We
         * want to flush the TLBs only after we're certain all the PTE updates
@@ -2540,7 +2554,9 @@ static void gen8_ggtt_clear_range(struct i915_address_space *vm,
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        unsigned first_entry = start >> PAGE_SHIFT;
        unsigned num_entries = length >> PAGE_SHIFT;
-       gen8_pte_t scratch_pte, __iomem *gtt_base =
+       const gen8_pte_t scratch_pte =
+               gen8_pte_encode(vm->scratch_page.daddr, I915_CACHE_LLC);
+       gen8_pte_t __iomem *gtt_base =
                (gen8_pte_t __iomem *)ggtt->gsm + first_entry;
        const int max_entries = ggtt_total_entries(ggtt) - first_entry;
        int i;
@@ -2550,8 +2566,6 @@ static void gen8_ggtt_clear_range(struct i915_address_space *vm,
                 first_entry, num_entries, max_entries))
                num_entries = max_entries;
 
-       scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
-                                     I915_CACHE_LLC);
        for (i = 0; i < num_entries; i++)
                gen8_set_pte(&gtt_base[i], scratch_pte);
        readl(gtt_base);