[Intel-gfx] [PATCH 2/9] drm/i915/gtt: Use a common type for page directories
Chris Wilson
chris at chris-wilson.co.uk
Tue Jun 11 19:43:34 UTC 2019
Quoting Mika Kuoppala (2019-06-11 18:27:24)
> All page directories are identical in function, only the position in the
> hierarchy differ. Use same base type for directory functionality.
>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Matthew Auld <matthew.william.auld at gmail.com>
> Cc: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 +-
> drivers/gpu/drm/i915/gt/intel_lrc_reg.h | 2 +-
> drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 2 +-
> drivers/gpu/drm/i915/gvt/scheduler.c | 30 +-
> drivers/gpu/drm/i915/i915_gem_gtt.c | 349 ++++++++++----------
> drivers/gpu/drm/i915/i915_gem_gtt.h | 64 ++--
> 6 files changed, 234 insertions(+), 215 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index c86ca9f21532..dbab0ab1cef1 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -1038,7 +1038,7 @@ static int emit_ppgtt_update(struct i915_request *rq, void *data)
>
> if (i915_vm_is_4lvl(vm)) {
> struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
> - const dma_addr_t pd_daddr = px_dma(&ppgtt->pml4);
> + const dma_addr_t pd_daddr = px_dma(ppgtt->pd);
>
> cs = intel_ring_begin(rq, 6);
> if (IS_ERR(cs))
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc_reg.h b/drivers/gpu/drm/i915/gt/intel_lrc_reg.h
> index 5ef932d810a7..6bf34738b4e5 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc_reg.h
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc_reg.h
> @@ -55,7 +55,7 @@
>
> #define ASSIGN_CTX_PML4(ppgtt, reg_state) do { \
> u32 *reg_state__ = (reg_state); \
> - const u64 addr__ = px_dma(&ppgtt->pml4); \
> + const u64 addr__ = px_dma(ppgtt->pd); \
> (reg_state__)[CTX_PDP0_UDW + 1] = upper_32_bits(addr__); \
> (reg_state__)[CTX_PDP0_LDW + 1] = lower_32_bits(addr__); \
> } while (0)
> diff --git a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> index c834d016c965..3b857994943c 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> @@ -1523,7 +1523,7 @@ static int load_pd_dir(struct i915_request *rq, const struct i915_ppgtt *ppgtt)
>
> *cs++ = MI_LOAD_REGISTER_IMM(1);
> *cs++ = i915_mmio_reg_offset(RING_PP_DIR_BASE(engine->mmio_base));
> - *cs++ = ppgtt->pd.base.ggtt_offset << 10;
> + *cs++ = ppgtt->pd->base.ggtt_offset << 10;
>
> intel_ring_advance(rq, cs);
>
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> index e301efb18d45..f1e1261ac3db 100644
> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> @@ -375,11 +375,13 @@ static int set_context_ppgtt_from_shadow(struct intel_vgpu_workload *workload,
> return -EINVAL;
>
> if (mm->ppgtt_mm.root_entry_type == GTT_TYPE_PPGTT_ROOT_L4_ENTRY) {
> - px_dma(&ppgtt->pml4) = mm->ppgtt_mm.shadow_pdps[0];
> + px_dma(ppgtt->pd) = mm->ppgtt_mm.shadow_pdps[0];
> } else {
> for (i = 0; i < GVT_RING_CTX_NR_PDPS; i++) {
> - px_dma(ppgtt->pdp.page_directory[i]) =
> - mm->ppgtt_mm.shadow_pdps[i];
> + struct i915_page_directory * const pd =
> + i915_pd_entry(ppgtt->pd, i);
> +
> + px_dma(pd) = mm->ppgtt_mm.shadow_pdps[i];
> }
> }
>
> @@ -1128,11 +1130,14 @@ i915_context_ppgtt_root_restore(struct intel_vgpu_submission *s,
> int i;
>
> if (i915_vm_is_4lvl(&ppgtt->vm)) {
> - px_dma(&ppgtt->pml4) = s->i915_context_pml4;
> + px_dma(ppgtt->pd) = s->i915_context_pml4;
> } else {
> - for (i = 0; i < GEN8_3LVL_PDPES; i++)
> - px_dma(ppgtt->pdp.page_directory[i]) =
> - s->i915_context_pdps[i];
> + for (i = 0; i < GEN8_3LVL_PDPES; i++) {
> + struct i915_page_directory * const pd =
> + i915_pd_entry(ppgtt->pd, i);
> +
> + px_dma(pd) = s->i915_context_pdps[i];
> + }
> }
> }
>
> @@ -1186,11 +1191,14 @@ i915_context_ppgtt_root_save(struct intel_vgpu_submission *s,
> int i;
>
> if (i915_vm_is_4lvl(&ppgtt->vm)) {
> - s->i915_context_pml4 = px_dma(&ppgtt->pml4);
> + s->i915_context_pml4 = px_dma(ppgtt->pd);
> } else {
> - for (i = 0; i < GEN8_3LVL_PDPES; i++)
> - s->i915_context_pdps[i] =
> - px_dma(ppgtt->pdp.page_directory[i]);
> + for (i = 0; i < GEN8_3LVL_PDPES; i++) {
> + struct i915_page_directory * const pd =
> + i915_pd_entry(ppgtt->pd, i);
> +
> + s->i915_context_pdps[i] = px_dma(pd);
> + }
> }
> }
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 07f86d474fa2..9a1f956a817a 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -661,7 +661,8 @@ static struct i915_page_table *alloc_pt(struct i915_address_space *vm)
> return ERR_PTR(-ENOMEM);
> }
>
> - atomic_set(&pt->used_ptes, 0);
> + atomic_set(&pt->used, 0);
> +
> return pt;
> }
>
> @@ -683,11 +684,28 @@ static void gen6_initialize_pt(struct i915_address_space *vm,
> fill32_px(vm, pt, vm->scratch_pte);
> }
>
> +static struct i915_page_directory *__alloc_pd(const unsigned int entries)
> +{
> + struct i915_page_directory *pd;
> +
> + pd = kmalloc(sizeof(*pd) +
> + entries * sizeof(pd->entry[0]), I915_GFP_ALLOW_FAIL);
> +
> + if (unlikely(!pd))
> + return NULL;
> +
> + memset(&pd->base, 0, sizeof(pd->base));
> + atomic_set(&pd->used, 0);
> + spin_lock_init(&pd->lock);
> +
> + return pd;
> +}
> +
> static struct i915_page_directory *alloc_pd(struct i915_address_space *vm)
> {
> struct i915_page_directory *pd;
>
> - pd = kmalloc(sizeof(*pd), I915_GFP_ALLOW_FAIL);
> + pd = __alloc_pd(512);
> if (unlikely(!pd))
> return ERR_PTR(-ENOMEM);
>
> @@ -696,8 +714,6 @@ static struct i915_page_directory *alloc_pd(struct i915_address_space *vm)
> return ERR_PTR(-ENOMEM);
> }
>
> - atomic_set(&pd->used_pdes, 0);
> - spin_lock_init(&pd->lock);
> return pd;
> }
>
> @@ -713,88 +729,56 @@ static void gen8_initialize_pd(struct i915_address_space *vm,
> {
> fill_px(vm, pd,
> gen8_pde_encode(px_dma(vm->scratch_pt), I915_CACHE_LLC));
> - memset_p((void **)pd->page_table, vm->scratch_pt, I915_PDES);
> + memset_p(pd->entry, vm->scratch_pt, I915_PDES);
> }
>
> -static int __pdp_init(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp)
> +static struct i915_page_directory *alloc_pdp(struct i915_address_space *vm)
> {
> - const unsigned int pdpes = i915_pdpes_per_pdp(vm);
> + struct i915_page_directory *pdp;
>
> - pdp->page_directory = kmalloc_array(pdpes, sizeof(*pdp->page_directory),
> - I915_GFP_ALLOW_FAIL);
> - if (unlikely(!pdp->page_directory))
> - return -ENOMEM;
> -
> - memset_p((void **)pdp->page_directory, vm->scratch_pd, pdpes);
> -
> - atomic_set(&pdp->used_pdpes, 0);
> - spin_lock_init(&pdp->lock);
> - return 0;
> -}
> -
> -static void __pdp_fini(struct i915_page_directory_pointer *pdp)
> -{
> - kfree(pdp->page_directory);
> - pdp->page_directory = NULL;
> -}
> -
> -static struct i915_page_directory_pointer *
> -alloc_pdp(struct i915_address_space *vm)
> -{
> - struct i915_page_directory_pointer *pdp;
> - int ret = -ENOMEM;
> -
> - GEM_BUG_ON(!i915_vm_is_4lvl(vm));
> -
> - pdp = kmalloc(sizeof(*pdp), GFP_KERNEL);
> + pdp = __alloc_pd(i915_pdpes_per_pdp(vm));
> if (!pdp)
> return ERR_PTR(-ENOMEM);
>
> - ret = __pdp_init(vm, pdp);
> - if (ret)
> - goto fail_bitmap;
> -
> - ret = setup_px(vm, pdp);
> - if (ret)
> - goto fail_page_m;
> + if (i915_vm_is_4lvl(vm)) {
> + if (unlikely(setup_px(vm, pdp))) {
> + kfree(pdp);
> + return ERR_PTR(-ENOMEM);
> + }
> + }
>
> return pdp;
> -
> -fail_page_m:
> - __pdp_fini(pdp);
> -fail_bitmap:
> - kfree(pdp);
> -
> - return ERR_PTR(ret);
> }
>
> static void free_pdp(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp)
> + struct i915_page_directory *pdp)
> {
> - __pdp_fini(pdp);
> -
> - if (!i915_vm_is_4lvl(vm))
> - return;
> + if (i915_vm_is_4lvl(vm))
> + cleanup_px(vm, pdp);
>
> - cleanup_px(vm, pdp);
> kfree(pdp);
> }
>
> -static void gen8_initialize_pdp(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp)
> +static void gen8_initialize_4lvl_pdp(struct i915_address_space *vm,
> + struct i915_page_directory *pdp)
> {
> fill_px(vm, pdp,
> gen8_pdpe_encode(px_dma(vm->scratch_pd), I915_CACHE_LLC));
> + memset_p(pdp->entry, vm->scratch_pd, 512);
> +}
> +
> +static void gen8_initialize_3lvl_pdp(struct i915_address_space *vm,
> + struct i915_page_directory *pdp)
> +{
> + memset_p(pdp->entry, vm->scratch_pd, GEN8_3LVL_PDPES);
> }
>
> static void gen8_initialize_pml4(struct i915_address_space *vm,
> - struct i915_pml4 *pml4)
> + struct i915_page_directory *pml4)
> {
> fill_px(vm, pml4,
> gen8_pml4e_encode(px_dma(vm->scratch_pdp), I915_CACHE_LLC));
> - memset_p((void **)pml4->pdps, vm->scratch_pdp, GEN8_PML4ES_PER_PML4);
> - spin_lock_init(&pml4->lock);
> + memset_p(pml4->entry, vm->scratch_pdp, GEN8_PML4ES_PER_PML4);
> }
>
> /*
> @@ -822,8 +806,8 @@ static bool gen8_ppgtt_clear_pt(const struct i915_address_space *vm,
> memset64(vaddr + gen8_pte_index(start), vm->scratch_pte, num_entries);
> kunmap_atomic(vaddr);
>
> - GEM_BUG_ON(num_entries > atomic_read(&pt->used_ptes));
> - return !atomic_sub_return(num_entries, &pt->used_ptes);
> + GEM_BUG_ON(num_entries > atomic_read(&pt->used));
> + return !atomic_sub_return(num_entries, &pt->used);
> }
>
> static void gen8_ppgtt_set_pde(struct i915_address_space *vm,
> @@ -854,12 +838,12 @@ static bool gen8_ppgtt_clear_pd(struct i915_address_space *vm,
> continue;
>
> spin_lock(&pd->lock);
> - if (!atomic_read(&pt->used_ptes)) {
> + if (!atomic_read(&pt->used)) {
> gen8_ppgtt_set_pde(vm, pd, vm->scratch_pt, pde);
> - pd->page_table[pde] = vm->scratch_pt;
> + pd->entry[pde] = vm->scratch_pt;
>
> - GEM_BUG_ON(!atomic_read(&pd->used_pdes));
> - atomic_dec(&pd->used_pdes);
> + GEM_BUG_ON(!atomic_read(&pd->used));
> + atomic_dec(&pd->used);
> free = true;
> }
> spin_unlock(&pd->lock);
> @@ -867,11 +851,11 @@ static bool gen8_ppgtt_clear_pd(struct i915_address_space *vm,
> free_pt(vm, pt);
> }
>
> - return !atomic_read(&pd->used_pdes);
> + return !atomic_read(&pd->used);
> }
>
> static void gen8_ppgtt_set_pdpe(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp,
> + struct i915_page_directory *pdp,
> struct i915_page_directory *pd,
> unsigned int pdpe)
> {
> @@ -889,7 +873,7 @@ static void gen8_ppgtt_set_pdpe(struct i915_address_space *vm,
> * Caller can use the return value to update higher-level entries
> */
> static bool gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp,
> + struct i915_page_directory * const pdp,
> u64 start, u64 length)
> {
> struct i915_page_directory *pd;
> @@ -904,12 +888,12 @@ static bool gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
> continue;
>
> spin_lock(&pdp->lock);
> - if (!atomic_read(&pd->used_pdes)) {
> + if (!atomic_read(&pd->used)) {
> gen8_ppgtt_set_pdpe(vm, pdp, vm->scratch_pd, pdpe);
> - pdp->page_directory[pdpe] = vm->scratch_pd;
> + pdp->entry[pdpe] = vm->scratch_pd;
>
> - GEM_BUG_ON(!atomic_read(&pdp->used_pdpes));
> - atomic_dec(&pdp->used_pdpes);
> + GEM_BUG_ON(!atomic_read(&pdp->used));
> + atomic_dec(&pdp->used);
> free = true;
> }
> spin_unlock(&pdp->lock);
> @@ -917,17 +901,17 @@ static bool gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
> free_pd(vm, pd);
> }
>
> - return !atomic_read(&pdp->used_pdpes);
> + return !atomic_read(&pdp->used);
> }
>
> static void gen8_ppgtt_clear_3lvl(struct i915_address_space *vm,
> u64 start, u64 length)
> {
> - gen8_ppgtt_clear_pdp(vm, &i915_vm_to_ppgtt(vm)->pdp, start, length);
> + gen8_ppgtt_clear_pdp(vm, i915_vm_to_ppgtt(vm)->pd, start, length);
> }
>
> -static void gen8_ppgtt_set_pml4e(struct i915_pml4 *pml4,
> - struct i915_page_directory_pointer *pdp,
> +static void gen8_ppgtt_set_pml4e(struct i915_page_directory *pml4,
> + struct i915_page_directory *pdp,
> unsigned int pml4e)
> {
> gen8_ppgtt_pml4e_t *vaddr;
> @@ -945,8 +929,8 @@ static void gen8_ppgtt_clear_4lvl(struct i915_address_space *vm,
> u64 start, u64 length)
> {
> struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
> - struct i915_pml4 *pml4 = &ppgtt->pml4;
> - struct i915_page_directory_pointer *pdp;
> + struct i915_page_directory * const pml4 = ppgtt->pd;
> + struct i915_page_directory *pdp;
> unsigned int pml4e;
>
> GEM_BUG_ON(!i915_vm_is_4lvl(vm));
> @@ -959,9 +943,9 @@ static void gen8_ppgtt_clear_4lvl(struct i915_address_space *vm,
> continue;
>
> spin_lock(&pml4->lock);
> - if (!atomic_read(&pdp->used_pdpes)) {
> + if (!atomic_read(&pdp->used)) {
> gen8_ppgtt_set_pml4e(pml4, vm->scratch_pdp, pml4e);
> - pml4->pdps[pml4e] = vm->scratch_pdp;
> + pml4->entry[pml4e] = vm->scratch_pdp;
> free = true;
> }
> spin_unlock(&pml4->lock);
> @@ -998,7 +982,7 @@ static __always_inline struct gen8_insert_pte gen8_insert_pte(u64 start)
>
> static __always_inline bool
> gen8_ppgtt_insert_pte_entries(struct i915_ppgtt *ppgtt,
> - struct i915_page_directory_pointer *pdp,
> + struct i915_page_directory *pdp,
> struct sgt_dma *iter,
> struct gen8_insert_pte *idx,
> enum i915_cache_level cache_level,
> @@ -1010,8 +994,8 @@ gen8_ppgtt_insert_pte_entries(struct i915_ppgtt *ppgtt,
> bool ret;
>
> GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(&ppgtt->vm));
> - pd = pdp->page_directory[idx->pdpe];
> - vaddr = kmap_atomic_px(pd->page_table[idx->pde]);
> + pd = i915_pd_entry(pdp, idx->pdpe);
> + vaddr = kmap_atomic_px(i915_pt_entry(pd, idx->pde));
> do {
> vaddr[idx->pte] = pte_encode | iter->dma;
>
> @@ -1041,11 +1025,11 @@ gen8_ppgtt_insert_pte_entries(struct i915_ppgtt *ppgtt,
> }
>
> GEM_BUG_ON(idx->pdpe >= i915_pdpes_per_pdp(&ppgtt->vm));
> - pd = pdp->page_directory[idx->pdpe];
> + pd = pdp->entry[idx->pdpe];
> }
>
> kunmap_atomic(vaddr);
> - vaddr = kmap_atomic_px(pd->page_table[idx->pde]);
> + vaddr = kmap_atomic_px(i915_pt_entry(pd, idx->pde));
> }
> } while (1);
> kunmap_atomic(vaddr);
> @@ -1062,14 +1046,14 @@ static void gen8_ppgtt_insert_3lvl(struct i915_address_space *vm,
> struct sgt_dma iter = sgt_dma(vma);
> struct gen8_insert_pte idx = gen8_insert_pte(vma->node.start);
>
> - gen8_ppgtt_insert_pte_entries(ppgtt, &ppgtt->pdp, &iter, &idx,
> + gen8_ppgtt_insert_pte_entries(ppgtt, ppgtt->pd, &iter, &idx,
> cache_level, flags);
>
> vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
> }
>
> static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
> - struct i915_page_directory_pointer **pdps,
> + struct i915_page_directory *pml4,
> struct sgt_dma *iter,
> enum i915_cache_level cache_level,
> u32 flags)
> @@ -1080,8 +1064,9 @@ static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
>
> do {
> struct gen8_insert_pte idx = gen8_insert_pte(start);
> - struct i915_page_directory_pointer *pdp = pdps[idx.pml4e];
> - struct i915_page_directory *pd = pdp->page_directory[idx.pdpe];
> + struct i915_page_directory *pdp =
> + i915_pdp_entry(pml4, idx.pml4e);
> + struct i915_page_directory *pd = i915_pd_entry(pdp, idx.pdpe);
> unsigned int page_size;
> bool maybe_64K = false;
> gen8_pte_t encode = pte_encode;
> @@ -1099,7 +1084,7 @@ static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
>
> vaddr = kmap_atomic_px(pd);
> } else {
> - struct i915_page_table *pt = pd->page_table[idx.pde];
> + struct i915_page_table *pt = i915_pt_entry(pd, idx.pde);
>
> index = idx.pte;
> max = GEN8_PTES;
> @@ -1174,7 +1159,8 @@ static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
> u16 i;
>
> encode = vma->vm->scratch_pte;
> - vaddr = kmap_atomic_px(pd->page_table[idx.pde]);
> + vaddr = kmap_atomic_px(i915_pt_entry(pd,
> + idx.pde));
>
> for (i = 1; i < index; i += 16)
> memset64(vaddr + i, encode, 15);
> @@ -1194,15 +1180,16 @@ static void gen8_ppgtt_insert_4lvl(struct i915_address_space *vm,
> {
> struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
> struct sgt_dma iter = sgt_dma(vma);
> - struct i915_page_directory_pointer **pdps = ppgtt->pml4.pdps;
> + struct i915_page_directory * const pml4 = ppgtt->pd;
>
> if (vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
> - gen8_ppgtt_insert_huge_entries(vma, pdps, &iter, cache_level,
> + gen8_ppgtt_insert_huge_entries(vma, pml4, &iter, cache_level,
> flags);
> } else {
> struct gen8_insert_pte idx = gen8_insert_pte(vma->node.start);
>
> - while (gen8_ppgtt_insert_pte_entries(ppgtt, pdps[idx.pml4e++],
> + while (gen8_ppgtt_insert_pte_entries(ppgtt,
> + i915_pdp_entry(pml4, idx.pml4e++),
> &iter, &idx, cache_level,
> flags))
> GEM_BUG_ON(idx.pml4e >= GEN8_PML4ES_PER_PML4);
> @@ -1217,8 +1204,8 @@ static void gen8_free_page_tables(struct i915_address_space *vm,
> int i;
>
> for (i = 0; i < I915_PDES; i++) {
> - if (pd->page_table[i] != vm->scratch_pt)
> - free_pt(vm, pd->page_table[i]);
> + if (pd->entry[i] != vm->scratch_pt)
> + free_pt(vm, pd->entry[i]);
> }
> }
>
> @@ -1277,7 +1264,7 @@ static int gen8_init_scratch(struct i915_address_space *vm)
> gen8_initialize_pt(vm, vm->scratch_pt);
> gen8_initialize_pd(vm, vm->scratch_pd);
> if (i915_vm_is_4lvl(vm))
> - gen8_initialize_pdp(vm, vm->scratch_pdp);
> + gen8_initialize_4lvl_pdp(vm, vm->scratch_pdp);
>
> return 0;
>
> @@ -1299,7 +1286,7 @@ static int gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
> int i;
>
> if (i915_vm_is_4lvl(vm)) {
> - const u64 daddr = px_dma(&ppgtt->pml4);
> + const u64 daddr = px_dma(ppgtt->pd);
>
> I915_WRITE(vgtif_reg(pdp[0].lo), lower_32_bits(daddr));
> I915_WRITE(vgtif_reg(pdp[0].hi), upper_32_bits(daddr));
> @@ -1336,17 +1323,17 @@ static void gen8_free_scratch(struct i915_address_space *vm)
> }
>
> static void gen8_ppgtt_cleanup_3lvl(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp)
> + struct i915_page_directory *pdp)
> {
> const unsigned int pdpes = i915_pdpes_per_pdp(vm);
> int i;
>
> for (i = 0; i < pdpes; i++) {
> - if (pdp->page_directory[i] == vm->scratch_pd)
> + if (pdp->entry[i] == vm->scratch_pd)
> continue;
>
> - gen8_free_page_tables(vm, pdp->page_directory[i]);
> - free_pd(vm, pdp->page_directory[i]);
> + gen8_free_page_tables(vm, pdp->entry[i]);
> + free_pd(vm, pdp->entry[i]);
> }
>
> free_pdp(vm, pdp);
> @@ -1354,16 +1341,19 @@ static void gen8_ppgtt_cleanup_3lvl(struct i915_address_space *vm,
>
> static void gen8_ppgtt_cleanup_4lvl(struct i915_ppgtt *ppgtt)
> {
> + struct i915_page_directory * const pml4 = ppgtt->pd;
> int i;
>
> for (i = 0; i < GEN8_PML4ES_PER_PML4; i++) {
> - if (ppgtt->pml4.pdps[i] == ppgtt->vm.scratch_pdp)
> + struct i915_page_directory *pdp = i915_pdp_entry(pml4, i);
> +
> + if (pdp == ppgtt->vm.scratch_pdp)
> continue;
>
> - gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, ppgtt->pml4.pdps[i]);
> + gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, pdp);
> }
>
> - cleanup_px(&ppgtt->vm, &ppgtt->pml4);
> + cleanup_px(&ppgtt->vm, pml4);
> }
>
> static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
> @@ -1377,7 +1367,7 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
> if (i915_vm_is_4lvl(vm))
> gen8_ppgtt_cleanup_4lvl(ppgtt);
> else
> - gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, &ppgtt->pdp);
> + gen8_ppgtt_cleanup_3lvl(&ppgtt->vm, ppgtt->pd);
>
> gen8_free_scratch(vm);
> }
> @@ -1406,10 +1396,10 @@ static int gen8_ppgtt_alloc_pd(struct i915_address_space *vm,
> if (count < GEN8_PTES || intel_vgpu_active(vm->i915))
> gen8_initialize_pt(vm, pt);
>
> - old = cmpxchg(&pd->page_table[pde], vm->scratch_pt, pt);
> + old = cmpxchg(&pd->entry[pde], vm->scratch_pt, pt);
> if (old == vm->scratch_pt) {
> gen8_ppgtt_set_pde(vm, pd, pt, pde);
> - atomic_inc(&pd->used_pdes);
> + atomic_inc(&pd->used);
> } else {
> free_pt(vm, pt);
> pt = old;
> @@ -1418,7 +1408,7 @@ static int gen8_ppgtt_alloc_pd(struct i915_address_space *vm,
> spin_lock(&pd->lock);
> }
>
> - atomic_add(count, &pt->used_ptes);
> + atomic_add(count, &pt->used);
> }
> spin_unlock(&pd->lock);
>
> @@ -1430,7 +1420,7 @@ static int gen8_ppgtt_alloc_pd(struct i915_address_space *vm,
> }
>
> static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
> - struct i915_page_directory_pointer *pdp,
> + struct i915_page_directory *pdp,
> u64 start, u64 length)
> {
> struct i915_page_directory *pd;
> @@ -1451,11 +1441,10 @@ static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
>
> gen8_initialize_pd(vm, pd);
>
> - old = cmpxchg(&pdp->page_directory[pdpe],
> - vm->scratch_pd, pd);
> + old = cmpxchg(&pdp->entry[pdpe], vm->scratch_pd, pd);
> if (old == vm->scratch_pd) {
> gen8_ppgtt_set_pdpe(vm, pdp, pd, pdpe);
> - atomic_inc(&pdp->used_pdpes);
> + atomic_inc(&pdp->used);
> } else {
> free_pd(vm, pd);
> pd = old;
> @@ -1463,7 +1452,7 @@ static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
>
> spin_lock(&pdp->lock);
> }
> - atomic_inc(&pd->used_pdes);
> + atomic_inc(&pd->used);
> spin_unlock(&pdp->lock);
>
> ret = gen8_ppgtt_alloc_pd(vm, pd, start, length);
> @@ -1471,7 +1460,7 @@ static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
> goto unwind_pd;
>
> spin_lock(&pdp->lock);
> - atomic_dec(&pd->used_pdes);
> + atomic_dec(&pd->used);
> }
> spin_unlock(&pdp->lock);
>
> @@ -1479,10 +1468,10 @@ static int gen8_ppgtt_alloc_pdp(struct i915_address_space *vm,
>
> unwind_pd:
> spin_lock(&pdp->lock);
> - if (atomic_dec_and_test(&pd->used_pdes)) {
> + if (atomic_dec_and_test(&pd->used)) {
> gen8_ppgtt_set_pdpe(vm, pdp, vm->scratch_pd, pdpe);
> - GEM_BUG_ON(!atomic_read(&pdp->used_pdpes));
> - atomic_dec(&pdp->used_pdpes);
> + GEM_BUG_ON(!atomic_read(&pdp->used));
> + atomic_dec(&pdp->used);
> free_pd(vm, pd);
> }
> spin_unlock(&pdp->lock);
> @@ -1495,23 +1484,24 @@ static int gen8_ppgtt_alloc_3lvl(struct i915_address_space *vm,
> u64 start, u64 length)
> {
> return gen8_ppgtt_alloc_pdp(vm,
> - &i915_vm_to_ppgtt(vm)->pdp, start, length);
> + i915_vm_to_ppgtt(vm)->pd, start, length);
> }
>
> static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
> u64 start, u64 length)
> {
> struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
> - struct i915_pml4 *pml4 = &ppgtt->pml4;
> - struct i915_page_directory_pointer *pdp;
> + struct i915_page_directory * const pml4 = ppgtt->pd;
> + struct i915_page_directory *pdp;
> u64 from = start;
> u32 pml4e;
> int ret;
>
> spin_lock(&pml4->lock);
> gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
> +
> if (pdp == vm->scratch_pdp) {
> - struct i915_page_directory_pointer *old;
> + struct i915_page_directory *old;
>
> spin_unlock(&pml4->lock);
>
> @@ -1519,9 +1509,9 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
> if (IS_ERR(pdp))
> goto unwind;
>
> - gen8_initialize_pdp(vm, pdp);
> + gen8_initialize_4lvl_pdp(vm, pdp);
>
> - old = cmpxchg(&pml4->pdps[pml4e], vm->scratch_pdp, pdp);
> + old = cmpxchg(&pml4->entry[pml4e], vm->scratch_pdp, pdp);
> if (old == vm->scratch_pdp) {
> gen8_ppgtt_set_pml4e(pml4, pdp, pml4e);
> } else {
> @@ -1531,7 +1521,7 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
>
> spin_lock(&pml4->lock);
> }
> - atomic_inc(&pdp->used_pdpes);
> + atomic_inc(&pdp->used);
> spin_unlock(&pml4->lock);
>
> ret = gen8_ppgtt_alloc_pdp(vm, pdp, start, length);
> @@ -1539,7 +1529,7 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
> goto unwind_pdp;
>
> spin_lock(&pml4->lock);
> - atomic_dec(&pdp->used_pdpes);
> + atomic_dec(&pdp->used);
> }
> spin_unlock(&pml4->lock);
>
> @@ -1547,7 +1537,7 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
>
> unwind_pdp:
> spin_lock(&pml4->lock);
> - if (atomic_dec_and_test(&pdp->used_pdpes)) {
> + if (atomic_dec_and_test(&pdp->used)) {
> gen8_ppgtt_set_pml4e(pml4, vm->scratch_pdp, pml4e);
> free_pdp(vm, pdp);
> }
> @@ -1560,7 +1550,7 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
> static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
> {
> struct i915_address_space *vm = &ppgtt->vm;
> - struct i915_page_directory_pointer *pdp = &ppgtt->pdp;
> + struct i915_page_directory *pdp = ppgtt->pd;
> struct i915_page_directory *pd;
> u64 start = 0, length = ppgtt->vm.total;
> u64 from = start;
> @@ -1573,10 +1563,12 @@ static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
>
> gen8_initialize_pd(vm, pd);
> gen8_ppgtt_set_pdpe(vm, pdp, pd, pdpe);
> - atomic_inc(&pdp->used_pdpes);
> +
> + atomic_inc(&pdp->used);
> }
>
> - atomic_inc(&pdp->used_pdpes); /* never remove */
> + atomic_inc(&pdp->used); /* never remove */
> +
> return 0;
>
> unwind:
> @@ -1585,7 +1577,7 @@ static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
> gen8_ppgtt_set_pdpe(vm, pdp, vm->scratch_pd, pdpe);
> free_pd(vm, pd);
> }
> - atomic_set(&pdp->used_pdpes, 0);
> + atomic_set(&pdp->used, 0);
> return -ENOMEM;
> }
>
> @@ -1640,27 +1632,25 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
> if (err)
> goto err_free;
>
> - if (i915_vm_is_4lvl(&ppgtt->vm)) {
> - err = setup_px(&ppgtt->vm, &ppgtt->pml4);
> - if (err)
> - goto err_scratch;
> + ppgtt->pd = alloc_pdp(&ppgtt->vm);
> + if (IS_ERR(ppgtt->pd)) {
> + err = PTR_ERR(ppgtt->pd);
> + goto err_scratch;
> + }
>
> - gen8_initialize_pml4(&ppgtt->vm, &ppgtt->pml4);
> + if (i915_vm_is_4lvl(&ppgtt->vm)) {
> + gen8_initialize_pml4(&ppgtt->vm, ppgtt->pd);
>
> ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc_4lvl;
> ppgtt->vm.insert_entries = gen8_ppgtt_insert_4lvl;
> ppgtt->vm.clear_range = gen8_ppgtt_clear_4lvl;
> } else {
> - err = __pdp_init(&ppgtt->vm, &ppgtt->pdp);
> - if (err)
> - goto err_scratch;
> + gen8_initialize_3lvl_pdp(&ppgtt->vm, ppgtt->pd);
>
> if (intel_vgpu_active(i915)) {
> err = gen8_preallocate_top_level_pdp(ppgtt);
> - if (err) {
> - __pdp_fini(&ppgtt->pdp);
> - goto err_scratch;
> - }
> + if (err)
> + goto err_pdp;
> }
>
> ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc_3lvl;
> @@ -1675,6 +1665,8 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
>
> return ppgtt;
>
> +err_pdp:
> + free_pdp(&ppgtt->vm, ppgtt->pd);
> err_scratch:
> gen8_free_scratch(&ppgtt->vm);
> err_free:
> @@ -1740,15 +1732,16 @@ static void gen6_ppgtt_enable(struct drm_i915_private *dev_priv)
> static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
> u64 start, u64 length)
> {
> - struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
> - unsigned int first_entry = start / I915_GTT_PAGE_SIZE;
> + struct gen6_ppgtt * const ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
> + const unsigned int first_entry = start / I915_GTT_PAGE_SIZE;
> + const gen6_pte_t scratch_pte = vm->scratch_pte;
> unsigned int pde = first_entry / GEN6_PTES;
> unsigned int pte = first_entry % GEN6_PTES;
> unsigned int num_entries = length / I915_GTT_PAGE_SIZE;
> - const gen6_pte_t scratch_pte = vm->scratch_pte;
>
> while (num_entries) {
> - struct i915_page_table *pt = ppgtt->base.pd.page_table[pde++];
> + struct i915_page_table * const pt =
> + i915_pt_entry(ppgtt->base.pd, pde++);
> const unsigned int count = min(num_entries, GEN6_PTES - pte);
> gen6_pte_t *vaddr;
>
> @@ -1756,8 +1749,8 @@ static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
>
> num_entries -= count;
>
> - GEM_BUG_ON(count > atomic_read(&pt->used_ptes));
> - if (!atomic_sub_return(count, &pt->used_ptes))
> + GEM_BUG_ON(count > atomic_read(&pt->used));
> + if (!atomic_sub_return(count, &pt->used))
> ppgtt->scan_for_unused_pt = true;
>
> /*
> @@ -1781,6 +1774,7 @@ static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
> u32 flags)
> {
> struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
> + struct i915_page_directory * const pd = ppgtt->pd;
> unsigned first_entry = vma->node.start / I915_GTT_PAGE_SIZE;
> unsigned act_pt = first_entry / GEN6_PTES;
> unsigned act_pte = first_entry % GEN6_PTES;
> @@ -1788,9 +1782,9 @@ static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
> struct sgt_dma iter = sgt_dma(vma);
> gen6_pte_t *vaddr;
>
> - GEM_BUG_ON(ppgtt->pd.page_table[act_pt] == vm->scratch_pt);
> + GEM_BUG_ON(i915_pt_entry(pd, act_pt) == vm->scratch_pt);
>
> - vaddr = kmap_atomic_px(ppgtt->pd.page_table[act_pt]);
> + vaddr = kmap_atomic_px(i915_pt_entry(pd, act_pt));
> do {
> vaddr[act_pte] = pte_encode | GEN6_PTE_ADDR_ENCODE(iter.dma);
>
> @@ -1806,7 +1800,7 @@ static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
>
> if (++act_pte == GEN6_PTES) {
> kunmap_atomic(vaddr);
> - vaddr = kmap_atomic_px(ppgtt->pd.page_table[++act_pt]);
> + vaddr = kmap_atomic_px(i915_pt_entry(pd, ++act_pt));
> act_pte = 0;
> }
> } while (1);
> @@ -1819,6 +1813,7 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
> u64 start, u64 length)
> {
> struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
> + struct i915_page_directory * const pd = ppgtt->base.pd;
> struct i915_page_table *pt;
> intel_wakeref_t wakeref;
> u64 from = start;
> @@ -1827,14 +1822,14 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
>
> wakeref = intel_runtime_pm_get(vm->i915);
>
> - spin_lock(&ppgtt->base.pd.lock);
> - gen6_for_each_pde(pt, &ppgtt->base.pd, start, length, pde) {
> + spin_lock(&pd->lock);
> + gen6_for_each_pde(pt, pd, start, length, pde) {
> const unsigned int count = gen6_pte_count(start, length);
>
> if (pt == vm->scratch_pt) {
> struct i915_page_table *old;
>
> - spin_unlock(&ppgtt->base.pd.lock);
> + spin_unlock(&pd->lock);
>
> pt = alloc_pt(vm);
> if (IS_ERR(pt))
> @@ -1842,10 +1837,8 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
>
> gen6_initialize_pt(vm, pt);
>
> - old = cmpxchg(&ppgtt->base.pd.page_table[pde],
> - vm->scratch_pt, pt);
> + old = cmpxchg(&pd->entry[pde], vm->scratch_pt, pt);
> if (old == vm->scratch_pt) {
> - ppgtt->base.pd.page_table[pde] = pt;
> if (i915_vma_is_bound(ppgtt->vma,
> I915_VMA_GLOBAL_BIND)) {
> gen6_write_pde(ppgtt, pde, pt);
> @@ -1856,12 +1849,12 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
> pt = old;
> }
>
> - spin_lock(&ppgtt->base.pd.lock);
> + spin_lock(&pd->lock);
> }
>
> - atomic_add(count, &pt->used_ptes);
> + atomic_add(count, &pt->used);
> }
> - spin_unlock(&ppgtt->base.pd.lock);
> + spin_unlock(&pd->lock);
>
> if (flush) {
> mark_tlbs_dirty(&ppgtt->base);
> @@ -1881,6 +1874,7 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
> static int gen6_ppgtt_init_scratch(struct gen6_ppgtt *ppgtt)
> {
> struct i915_address_space * const vm = &ppgtt->base.vm;
> + struct i915_page_directory * const pd = ppgtt->base.pd;
> struct i915_page_table *unused;
> u32 pde;
> int ret;
> @@ -1900,9 +1894,9 @@ static int gen6_ppgtt_init_scratch(struct gen6_ppgtt *ppgtt)
> }
>
> gen6_initialize_pt(vm, vm->scratch_pt);
> - gen6_for_all_pdes(unused, &ppgtt->base.pd, pde)
> - ppgtt->base.pd.page_table[pde] = vm->scratch_pt;
> - spin_lock_init(&ppgtt->base.pd.lock);
> +
> + gen6_for_all_pdes(unused, pd, pde)
> + pd->entry[pde] = vm->scratch_pt;
>
> return 0;
> }
> @@ -1915,10 +1909,11 @@ static void gen6_ppgtt_free_scratch(struct i915_address_space *vm)
>
> static void gen6_ppgtt_free_pd(struct gen6_ppgtt *ppgtt)
> {
> + struct i915_page_directory * const pd = ppgtt->base.pd;
> struct i915_page_table *pt;
> u32 pde;
>
> - gen6_for_all_pdes(pt, &ppgtt->base.pd, pde)
> + gen6_for_all_pdes(pt, pd, pde)
> if (pt != ppgtt->base.vm.scratch_pt)
> free_pt(&ppgtt->base.vm, pt);
> }
> @@ -1982,6 +1977,7 @@ static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
>
> gen6_ppgtt_free_pd(ppgtt);
> gen6_ppgtt_free_scratch(vm);
> + kfree(ppgtt->base.pd);
> }
>
> static int pd_vma_set_pages(struct i915_vma *vma)
> @@ -2007,10 +2003,10 @@ static int pd_vma_bind(struct i915_vma *vma,
> struct i915_page_table *pt;
> unsigned int pde;
>
> - ppgtt->base.pd.base.ggtt_offset = ggtt_offset * sizeof(gen6_pte_t);
> + ppgtt->base.pd->base.ggtt_offset = ggtt_offset * sizeof(gen6_pte_t);
> ppgtt->pd_addr = (gen6_pte_t __iomem *)ggtt->gsm + ggtt_offset;
>
> - gen6_for_all_pdes(pt, &ppgtt->base.pd, pde)
> + gen6_for_all_pdes(pt, ppgtt->base.pd, pde)
> gen6_write_pde(ppgtt, pde, pt);
>
> mark_tlbs_dirty(&ppgtt->base);
> @@ -2022,6 +2018,7 @@ static int pd_vma_bind(struct i915_vma *vma,
> static void pd_vma_unbind(struct i915_vma *vma)
> {
> struct gen6_ppgtt *ppgtt = vma->private;
> + struct i915_page_directory * const pd = ppgtt->base.pd;
> struct i915_page_table * const scratch_pt = ppgtt->base.vm.scratch_pt;
> struct i915_page_table *pt;
> unsigned int pde;
> @@ -2030,12 +2027,12 @@ static void pd_vma_unbind(struct i915_vma *vma)
> return;
>
> /* Free all no longer used page tables */
> - gen6_for_all_pdes(pt, &ppgtt->base.pd, pde) {
> - if (atomic_read(&pt->used_ptes) || pt == scratch_pt)
> + gen6_for_all_pdes(pt, ppgtt->base.pd, pde) {
> + if (atomic_read(&pt->used) || pt == scratch_pt)
> continue;
>
> free_pt(&ppgtt->base.vm, pt);
> - ppgtt->base.pd.page_table[pde] = scratch_pt;
> + pd->entry[pde] = scratch_pt;
> }
>
> ppgtt->scan_for_unused_pt = false;
> @@ -2164,9 +2161,15 @@ static struct i915_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
> goto err_free;
> }
>
> + ppgtt->base.pd = __alloc_pd(512);
> + if (!ppgtt->base.pd) {
> + err = -ENOMEM;
> + goto err_work;
> + }
> +
> err = gen6_ppgtt_init_scratch(ppgtt);
> if (err)
> - goto err_work;
> + goto err_pd;
>
> ppgtt->vma = pd_vma_create(ppgtt, GEN6_PD_SIZE);
> if (IS_ERR(ppgtt->vma)) {
> @@ -2178,6 +2181,8 @@ static struct i915_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
>
> err_scratch:
> gen6_ppgtt_free_scratch(&ppgtt->base.vm);
> +err_pd:
> + kfree(ppgtt->base.pd);
> err_work:
> kfree(ppgtt->work);
> err_free:
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index 89437d0a721c..49f44071def4 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -248,28 +248,14 @@ struct i915_page_dma {
>
> struct i915_page_table {
> struct i915_page_dma base;
> - atomic_t used_ptes;
> + atomic_t used;
> };
>
> struct i915_page_directory {
> struct i915_page_dma base;
> -
> - struct i915_page_table *page_table[I915_PDES]; /* PDEs */
> - atomic_t used_pdes;
> - spinlock_t lock;
> -};
> -
> -struct i915_page_directory_pointer {
> - struct i915_page_dma base;
> - struct i915_page_directory **page_directory;
> - atomic_t used_pdpes;
> - spinlock_t lock;
> -};
> -
> -struct i915_pml4 {
> - struct i915_page_dma base;
> - struct i915_page_directory_pointer *pdps[GEN8_PML4ES_PER_PML4];
> + atomic_t used;
> spinlock_t lock;
> + void *entry[0];
> };
Furthermore, we can say that only two types of pointer could be stored
here. However, unions tend to end up with messy code, so I can
understand if the implicit casts from void end up being neater.
-Chris
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