Re: [PATCH v2 1/4] drm/i915: enforce min GTT alignment for discrete cards
From: Ramalingam C
Date: Thu Jan 20 2022 - 06:46:35 EST
On 2022-01-18 at 17:50:34 +0000, Robert Beckett wrote:
> From: Matthew Auld <matthew.auld@xxxxxxxxx>
>
> For local-memory objects we need to align the GTT addresses
> to 64K, both for the ppgtt and ggtt.
>
> We need to support vm->min_alignment > 4K, depending
> on the vm itself and the type of object we are inserting.
> With this in mind update the GTT selftests to take this
> into account.
>
> For DG2 we further align and pad lmem object GTT addresses
> to 2MB to ensure PDEs contain consistent page sizes as
> required by the HW.
>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx>
> Signed-off-by: Robert Beckett <bob.beckett@xxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> ---
> .../i915/gem/selftests/i915_gem_client_blt.c | 23 +++--
> drivers/gpu/drm/i915/gt/intel_gtt.c | 14 +++
> drivers/gpu/drm/i915/gt/intel_gtt.h | 9 ++
> drivers/gpu/drm/i915/i915_vma.c | 14 +++
> drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 96 ++++++++++++-------
> 5 files changed, 115 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
> index c08f766e6e15..7fee95a65414 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
> @@ -39,6 +39,7 @@ struct tiled_blits {
> struct blit_buffer scratch;
> struct i915_vma *batch;
> u64 hole;
> + u64 align;
> u32 width;
> u32 height;
> };
> @@ -410,14 +411,21 @@ tiled_blits_create(struct intel_engine_cs *engine, struct rnd_state *prng)
> goto err_free;
> }
>
> - hole_size = 2 * PAGE_ALIGN(WIDTH * HEIGHT * 4);
> + t->align = I915_GTT_PAGE_SIZE_2M; /* XXX worst case, derive from vm! */
> + t->align = max(t->align,
> + i915_vm_min_alignment(t->ce->vm, INTEL_MEMORY_LOCAL));
> + t->align = max(t->align,
> + i915_vm_min_alignment(t->ce->vm, INTEL_MEMORY_SYSTEM));
> +
> + hole_size = 2 * round_up(WIDTH * HEIGHT * 4, t->align);
> hole_size *= 2; /* room to maneuver */
> - hole_size += 2 * I915_GTT_MIN_ALIGNMENT;
> + hole_size += 2 * t->align; /* padding on either side */
>
> mutex_lock(&t->ce->vm->mutex);
> memset(&hole, 0, sizeof(hole));
> err = drm_mm_insert_node_in_range(&t->ce->vm->mm, &hole,
> - hole_size, 0, I915_COLOR_UNEVICTABLE,
> + hole_size, t->align,
> + I915_COLOR_UNEVICTABLE,
> 0, U64_MAX,
> DRM_MM_INSERT_BEST);
> if (!err)
> @@ -428,7 +436,7 @@ tiled_blits_create(struct intel_engine_cs *engine, struct rnd_state *prng)
> goto err_put;
> }
>
> - t->hole = hole.start + I915_GTT_MIN_ALIGNMENT;
> + t->hole = hole.start + t->align;
> pr_info("Using hole at %llx\n", t->hole);
>
> err = tiled_blits_create_buffers(t, WIDTH, HEIGHT, prng);
> @@ -455,7 +463,7 @@ static void tiled_blits_destroy(struct tiled_blits *t)
> static int tiled_blits_prepare(struct tiled_blits *t,
> struct rnd_state *prng)
> {
> - u64 offset = PAGE_ALIGN(t->width * t->height * 4);
> + u64 offset = round_up(t->width * t->height * 4, t->align);
> u32 *map;
> int err;
> int i;
> @@ -486,8 +494,7 @@ static int tiled_blits_prepare(struct tiled_blits *t,
>
> static int tiled_blits_bounce(struct tiled_blits *t, struct rnd_state *prng)
> {
> - u64 offset =
> - round_up(t->width * t->height * 4, 2 * I915_GTT_MIN_ALIGNMENT);
> + u64 offset = round_up(t->width * t->height * 4, 2 * t->align);
> int err;
>
> /* We want to check position invariant tiling across GTT eviction */
> @@ -500,7 +507,7 @@ static int tiled_blits_bounce(struct tiled_blits *t, struct rnd_state *prng)
>
> /* Reposition so that we overlap the old addresses, and slightly off */
> err = tiled_blit(t,
> - &t->buffers[2], t->hole + I915_GTT_MIN_ALIGNMENT,
> + &t->buffers[2], t->hole + t->align,
> &t->buffers[1], t->hole + 3 * offset / 2);
> if (err)
> return err;
> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
> index 46be4197b93f..7c92b25c0f26 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gtt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
> @@ -223,6 +223,20 @@ void i915_address_space_init(struct i915_address_space *vm, int subclass)
>
> GEM_BUG_ON(!vm->total);
> drm_mm_init(&vm->mm, 0, vm->total);
> +
> + memset64(vm->min_alignment, I915_GTT_MIN_ALIGNMENT,
> + ARRAY_SIZE(vm->min_alignment));
> +
> + if (HAS_64K_PAGES(vm->i915)) {
> + if (IS_DG2(vm->i915)) {
I think we need this 2M alignment for all platform with HAS_64K_PAGES.
Not only for DG2.
> + vm->min_alignment[INTEL_MEMORY_LOCAL] = I915_GTT_PAGE_SIZE_2M;
> + vm->min_alignment[INTEL_MEMORY_STOLEN_LOCAL] = I915_GTT_PAGE_SIZE_2M;
> + } else {
> + vm->min_alignment[INTEL_MEMORY_LOCAL] = I915_GTT_PAGE_SIZE_64K;
> + vm->min_alignment[INTEL_MEMORY_STOLEN_LOCAL] = I915_GTT_PAGE_SIZE_64K;
> + }
> + }
> +
> vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;
>
> INIT_LIST_HEAD(&vm->bound_list);
> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
> index 8073438b67c8..b8da2514d601 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gtt.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
> @@ -29,6 +29,8 @@
> #include "i915_selftest.h"
> #include "i915_vma_resource.h"
> #include "i915_vma_types.h"
> +#include "i915_params.h"
> +#include "intel_memory_region.h"
>
> #define I915_GFP_ALLOW_FAIL (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN)
>
> @@ -223,6 +225,7 @@ struct i915_address_space {
> struct device *dma;
> u64 total; /* size addr space maps (ex. 2GB for ggtt) */
> u64 reserved; /* size addr space reserved */
> + u64 min_alignment[INTEL_MEMORY_STOLEN_LOCAL + 1];
>
> unsigned int bind_async_flags;
>
> @@ -384,6 +387,12 @@ i915_vm_has_scratch_64K(struct i915_address_space *vm)
> return vm->scratch_order == get_order(I915_GTT_PAGE_SIZE_64K);
> }
>
> +static inline u64 i915_vm_min_alignment(struct i915_address_space *vm,
> + enum intel_memory_type type)
> +{
> + return vm->min_alignment[type];
> +}
> +
> static inline bool
> i915_vm_has_cache_coloring(struct i915_address_space *vm)
> {
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 1f15c3298112..9ac92e7a3566 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -756,6 +756,20 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
> }
>
> color = 0;
> +
> + if (HAS_64K_PAGES(vma->vm->i915) && i915_gem_object_is_lmem(vma->obj)) {
> + alignment = max(alignment, I915_GTT_PAGE_SIZE_64K);
> + /*
> + * DG2 can not have different sized pages in any given PDE (2MB range).
> + * Keeping things simple, we force any lmem object to reserve
> + * 2MB chunks, preventing any smaller pages being used alongside
> + */
> + if (IS_DG2(vma->vm->i915)) {
Similarly here we dont need special case for DG2.
Ram
> + alignment = max(alignment, I915_GTT_PAGE_SIZE_2M);
> + size = round_up(size, I915_GTT_PAGE_SIZE_2M);
> + }
> + }
> +
> if (i915_vm_has_cache_coloring(vma->vm))
> color = vma->obj->cache_level;
>
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
> index 076d860ce01a..2f3f0c01786b 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
> @@ -238,6 +238,8 @@ static int lowlevel_hole(struct i915_address_space *vm,
> u64 hole_start, u64 hole_end,
> unsigned long end_time)
> {
> + const unsigned int min_alignment =
> + i915_vm_min_alignment(vm, INTEL_MEMORY_SYSTEM);
> I915_RND_STATE(seed_prng);
> struct i915_vma_resource *mock_vma_res;
> unsigned int size;
> @@ -251,9 +253,10 @@ static int lowlevel_hole(struct i915_address_space *vm,
> I915_RND_SUBSTATE(prng, seed_prng);
> struct drm_i915_gem_object *obj;
> unsigned int *order, count, n;
> - u64 hole_size;
> + u64 hole_size, aligned_size;
>
> - hole_size = (hole_end - hole_start) >> size;
> + aligned_size = max_t(u32, ilog2(min_alignment), size);
> + hole_size = (hole_end - hole_start) >> aligned_size;
> if (hole_size > KMALLOC_MAX_SIZE / sizeof(u32))
> hole_size = KMALLOC_MAX_SIZE / sizeof(u32);
> count = hole_size >> 1;
> @@ -274,8 +277,8 @@ static int lowlevel_hole(struct i915_address_space *vm,
> }
> GEM_BUG_ON(!order);
>
> - GEM_BUG_ON(count * BIT_ULL(size) > vm->total);
> - GEM_BUG_ON(hole_start + count * BIT_ULL(size) > hole_end);
> + GEM_BUG_ON(count * BIT_ULL(aligned_size) > vm->total);
> + GEM_BUG_ON(hole_start + count * BIT_ULL(aligned_size) > hole_end);
>
> /* Ignore allocation failures (i.e. don't report them as
> * a test failure) as we are purposefully allocating very
> @@ -298,10 +301,10 @@ static int lowlevel_hole(struct i915_address_space *vm,
> }
>
> for (n = 0; n < count; n++) {
> - u64 addr = hole_start + order[n] * BIT_ULL(size);
> + u64 addr = hole_start + order[n] * BIT_ULL(aligned_size);
> intel_wakeref_t wakeref;
>
> - GEM_BUG_ON(addr + BIT_ULL(size) > vm->total);
> + GEM_BUG_ON(addr + BIT_ULL(aligned_size) > vm->total);
>
> if (igt_timeout(end_time,
> "%s timed out before %d/%d\n",
> @@ -344,7 +347,7 @@ static int lowlevel_hole(struct i915_address_space *vm,
> }
>
> mock_vma_res->bi.pages = obj->mm.pages;
> - mock_vma_res->node_size = BIT_ULL(size);
> + mock_vma_res->node_size = BIT_ULL(aligned_size);
> mock_vma_res->start = addr;
>
> with_intel_runtime_pm(vm->gt->uncore->rpm, wakeref)
> @@ -355,7 +358,7 @@ static int lowlevel_hole(struct i915_address_space *vm,
>
> i915_random_reorder(order, count, &prng);
> for (n = 0; n < count; n++) {
> - u64 addr = hole_start + order[n] * BIT_ULL(size);
> + u64 addr = hole_start + order[n] * BIT_ULL(aligned_size);
> intel_wakeref_t wakeref;
>
> GEM_BUG_ON(addr + BIT_ULL(size) > vm->total);
> @@ -399,8 +402,10 @@ static int fill_hole(struct i915_address_space *vm,
> {
> const u64 hole_size = hole_end - hole_start;
> struct drm_i915_gem_object *obj;
> + const unsigned int min_alignment =
> + i915_vm_min_alignment(vm, INTEL_MEMORY_SYSTEM);
> const unsigned long max_pages =
> - min_t(u64, ULONG_MAX - 1, hole_size/2 >> PAGE_SHIFT);
> + min_t(u64, ULONG_MAX - 1, (hole_size / 2) >> ilog2(min_alignment));
> const unsigned long max_step = max(int_sqrt(max_pages), 2UL);
> unsigned long npages, prime, flags;
> struct i915_vma *vma;
> @@ -441,14 +446,17 @@ static int fill_hole(struct i915_address_space *vm,
>
> offset = p->offset;
> list_for_each_entry(obj, &objects, st_link) {
> + u64 aligned_size = round_up(obj->base.size,
> + min_alignment);
> +
> vma = i915_vma_instance(obj, vm, NULL);
> if (IS_ERR(vma))
> continue;
>
> if (p->step < 0) {
> - if (offset < hole_start + obj->base.size)
> + if (offset < hole_start + aligned_size)
> break;
> - offset -= obj->base.size;
> + offset -= aligned_size;
> }
>
> err = i915_vma_pin(vma, 0, 0, offset | flags);
> @@ -470,22 +478,25 @@ static int fill_hole(struct i915_address_space *vm,
> i915_vma_unpin(vma);
>
> if (p->step > 0) {
> - if (offset + obj->base.size > hole_end)
> + if (offset + aligned_size > hole_end)
> break;
> - offset += obj->base.size;
> + offset += aligned_size;
> }
> }
>
> offset = p->offset;
> list_for_each_entry(obj, &objects, st_link) {
> + u64 aligned_size = round_up(obj->base.size,
> + min_alignment);
> +
> vma = i915_vma_instance(obj, vm, NULL);
> if (IS_ERR(vma))
> continue;
>
> if (p->step < 0) {
> - if (offset < hole_start + obj->base.size)
> + if (offset < hole_start + aligned_size)
> break;
> - offset -= obj->base.size;
> + offset -= aligned_size;
> }
>
> if (!drm_mm_node_allocated(&vma->node) ||
> @@ -506,22 +517,25 @@ static int fill_hole(struct i915_address_space *vm,
> }
>
> if (p->step > 0) {
> - if (offset + obj->base.size > hole_end)
> + if (offset + aligned_size > hole_end)
> break;
> - offset += obj->base.size;
> + offset += aligned_size;
> }
> }
>
> offset = p->offset;
> list_for_each_entry_reverse(obj, &objects, st_link) {
> + u64 aligned_size = round_up(obj->base.size,
> + min_alignment);
> +
> vma = i915_vma_instance(obj, vm, NULL);
> if (IS_ERR(vma))
> continue;
>
> if (p->step < 0) {
> - if (offset < hole_start + obj->base.size)
> + if (offset < hole_start + aligned_size)
> break;
> - offset -= obj->base.size;
> + offset -= aligned_size;
> }
>
> err = i915_vma_pin(vma, 0, 0, offset | flags);
> @@ -543,22 +557,25 @@ static int fill_hole(struct i915_address_space *vm,
> i915_vma_unpin(vma);
>
> if (p->step > 0) {
> - if (offset + obj->base.size > hole_end)
> + if (offset + aligned_size > hole_end)
> break;
> - offset += obj->base.size;
> + offset += aligned_size;
> }
> }
>
> offset = p->offset;
> list_for_each_entry_reverse(obj, &objects, st_link) {
> + u64 aligned_size = round_up(obj->base.size,
> + min_alignment);
> +
> vma = i915_vma_instance(obj, vm, NULL);
> if (IS_ERR(vma))
> continue;
>
> if (p->step < 0) {
> - if (offset < hole_start + obj->base.size)
> + if (offset < hole_start + aligned_size)
> break;
> - offset -= obj->base.size;
> + offset -= aligned_size;
> }
>
> if (!drm_mm_node_allocated(&vma->node) ||
> @@ -579,9 +596,9 @@ static int fill_hole(struct i915_address_space *vm,
> }
>
> if (p->step > 0) {
> - if (offset + obj->base.size > hole_end)
> + if (offset + aligned_size > hole_end)
> break;
> - offset += obj->base.size;
> + offset += aligned_size;
> }
> }
> }
> @@ -611,6 +628,7 @@ static int walk_hole(struct i915_address_space *vm,
> const u64 hole_size = hole_end - hole_start;
> const unsigned long max_pages =
> min_t(u64, ULONG_MAX - 1, hole_size >> PAGE_SHIFT);
> + unsigned long min_alignment;
> unsigned long flags;
> u64 size;
>
> @@ -620,6 +638,8 @@ static int walk_hole(struct i915_address_space *vm,
> if (i915_is_ggtt(vm))
> flags |= PIN_GLOBAL;
>
> + min_alignment = i915_vm_min_alignment(vm, INTEL_MEMORY_SYSTEM);
> +
> for_each_prime_number_from(size, 1, max_pages) {
> struct drm_i915_gem_object *obj;
> struct i915_vma *vma;
> @@ -638,7 +658,7 @@ static int walk_hole(struct i915_address_space *vm,
>
> for (addr = hole_start;
> addr + obj->base.size < hole_end;
> - addr += obj->base.size) {
> + addr += round_up(obj->base.size, min_alignment)) {
> err = i915_vma_pin(vma, 0, 0, addr | flags);
> if (err) {
> pr_err("%s bind failed at %llx + %llx [hole %llx- %llx] with err=%d\n",
> @@ -690,6 +710,7 @@ static int pot_hole(struct i915_address_space *vm,
> {
> struct drm_i915_gem_object *obj;
> struct i915_vma *vma;
> + unsigned int min_alignment;
> unsigned long flags;
> unsigned int pot;
> int err = 0;
> @@ -698,6 +719,8 @@ static int pot_hole(struct i915_address_space *vm,
> if (i915_is_ggtt(vm))
> flags |= PIN_GLOBAL;
>
> + min_alignment = i915_vm_min_alignment(vm, INTEL_MEMORY_SYSTEM);
> +
> obj = i915_gem_object_create_internal(vm->i915, 2 * I915_GTT_PAGE_SIZE);
> if (IS_ERR(obj))
> return PTR_ERR(obj);
> @@ -710,13 +733,13 @@ static int pot_hole(struct i915_address_space *vm,
>
> /* Insert a pair of pages across every pot boundary within the hole */
> for (pot = fls64(hole_end - 1) - 1;
> - pot > ilog2(2 * I915_GTT_PAGE_SIZE);
> + pot > ilog2(2 * min_alignment);
> pot--) {
> u64 step = BIT_ULL(pot);
> u64 addr;
>
> - for (addr = round_up(hole_start + I915_GTT_PAGE_SIZE, step) - I915_GTT_PAGE_SIZE;
> - addr <= round_down(hole_end - 2*I915_GTT_PAGE_SIZE, step) - I915_GTT_PAGE_SIZE;
> + for (addr = round_up(hole_start + min_alignment, step) - min_alignment;
> + addr <= round_down(hole_end - (2 * min_alignment), step) - min_alignment;
> addr += step) {
> err = i915_vma_pin(vma, 0, 0, addr | flags);
> if (err) {
> @@ -761,6 +784,7 @@ static int drunk_hole(struct i915_address_space *vm,
> unsigned long end_time)
> {
> I915_RND_STATE(prng);
> + unsigned int min_alignment;
> unsigned int size;
> unsigned long flags;
>
> @@ -768,15 +792,18 @@ static int drunk_hole(struct i915_address_space *vm,
> if (i915_is_ggtt(vm))
> flags |= PIN_GLOBAL;
>
> + min_alignment = i915_vm_min_alignment(vm, INTEL_MEMORY_SYSTEM);
> +
> /* Keep creating larger objects until one cannot fit into the hole */
> for (size = 12; (hole_end - hole_start) >> size; size++) {
> struct drm_i915_gem_object *obj;
> unsigned int *order, count, n;
> struct i915_vma *vma;
> - u64 hole_size;
> + u64 hole_size, aligned_size;
> int err = -ENODEV;
>
> - hole_size = (hole_end - hole_start) >> size;
> + aligned_size = max_t(u32, ilog2(min_alignment), size);
> + hole_size = (hole_end - hole_start) >> aligned_size;
> if (hole_size > KMALLOC_MAX_SIZE / sizeof(u32))
> hole_size = KMALLOC_MAX_SIZE / sizeof(u32);
> count = hole_size >> 1;
> @@ -816,7 +843,7 @@ static int drunk_hole(struct i915_address_space *vm,
> GEM_BUG_ON(vma->size != BIT_ULL(size));
>
> for (n = 0; n < count; n++) {
> - u64 addr = hole_start + order[n] * BIT_ULL(size);
> + u64 addr = hole_start + order[n] * BIT_ULL(aligned_size);
>
> err = i915_vma_pin(vma, 0, 0, addr | flags);
> if (err) {
> @@ -868,11 +895,14 @@ static int __shrink_hole(struct i915_address_space *vm,
> {
> struct drm_i915_gem_object *obj;
> unsigned long flags = PIN_OFFSET_FIXED | PIN_USER;
> + unsigned int min_alignment;
> unsigned int order = 12;
> LIST_HEAD(objects);
> int err = 0;
> u64 addr;
>
> + min_alignment = i915_vm_min_alignment(vm, INTEL_MEMORY_SYSTEM);
> +
> /* Keep creating larger objects until one cannot fit into the hole */
> for (addr = hole_start; addr < hole_end; ) {
> struct i915_vma *vma;
> @@ -913,7 +943,7 @@ static int __shrink_hole(struct i915_address_space *vm,
> }
>
> i915_vma_unpin(vma);
> - addr += size;
> + addr += round_up(size, min_alignment);
>
> /*
> * Since we are injecting allocation faults at random intervals,
> --
> 2.25.1
>