/* $NetBSD: i915_gem_gtt.c,v 1.24 2022/08/20 23:19:09 riastradh Exp $ */
// SPDX-License-Identifier: MIT
/*
* Copyright © 2010 Daniel Vetter
* Copyright © 2020 Intel Corporation
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: i915_gem_gtt.c,v 1.24 2022/08/20 23:19:09 riastradh Exp $");
#include <linux/slab.h> /* fault-inject.h is not standalone! */
#include <linux/fault-inject.h>
#include <linux/log2.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/stop_machine.h>
#include <asm/set_memory.h>
#include <asm/smp.h>
#include <drm/i915_drm.h>
#include "display/intel_frontbuffer.h"
#include "gt/intel_gt.h"
#include "gt/intel_gt_requests.h"
#include "i915_drv.h"
#include "i915_scatterlist.h"
#include "i915_trace.h"
#include "i915_vgpu.h"
#ifdef __NetBSD__
#include <drm/bus_dma_hacks.h>
#include <x86/machdep.h>
#include <machine/pte.h>
#define _PAGE_PRESENT PTE_P /* 0x01 PTE is present */
#define _PAGE_RW PTE_W /* 0x02 read/write */
#define _PAGE_PWT PTE_PWT /* 0x08 page write-through */
#define _PAGE_PCD PTE_PCD /* 0x10 page cache disabled */
#define _PAGE_PAT PTE_PAT /* 0x80 page attribute table on PTE */
#endif
int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
struct sg_table *pages)
{
do {
#ifdef __NetBSD__
if (dma_map_sg_attrs(obj->base.dev->dmat,
pages->sgl, pages->nents,
PCI_DMA_BIDIRECTIONAL,
DMA_ATTR_NO_WARN))
return 0;
#else
if (dma_map_sg_attrs(&obj->base.dev->pdev->dev,
pages->sgl, pages->nents,
PCI_DMA_BIDIRECTIONAL,
DMA_ATTR_NO_WARN))
return 0;
#endif
/*
* If the DMA remap fails, one cause can be that we have
* too many objects pinned in a small remapping table,
* such as swiotlb. Incrementally purge all other objects and
* try again - if there are no more pages to remove from
* the DMA remapper, i915_gem_shrink will return 0.
*/
GEM_BUG_ON(obj->mm.pages == pages);
} while (i915_gem_shrink(to_i915(obj->base.dev),
obj->base.size >> PAGE_SHIFT, NULL,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND));
return -ENOSPC;
}
void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
struct sg_table *pages)
{
struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
#ifdef __NetBSD__
bus_dma_tag_t kdev = dev_priv->drm.dmat;
#else
struct device *kdev = &dev_priv->drm.pdev->dev;
#endif
struct i915_ggtt *ggtt = &dev_priv->ggtt;
if (unlikely(ggtt->do_idle_maps)) {
/* XXX This does not prevent more requests being submitted! */
if (intel_gt_retire_requests_timeout(ggtt->vm.gt,
-MAX_SCHEDULE_TIMEOUT)) {
DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");
/* Wait a bit, in hopes it avoids the hang */
udelay(10);
}
}
dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL);
}
/**
* i915_gem_gtt_reserve - reserve a node in an address_space (GTT)
* @vm: the &struct i915_address_space
* @node: the &struct drm_mm_node (typically i915_vma.mode)
* @size: how much space to allocate inside the GTT,
* must be #I915_GTT_PAGE_SIZE aligned
* @offset: where to insert inside the GTT,
* must be #I915_GTT_MIN_ALIGNMENT aligned, and the node
* (@offset + @size) must fit within the address space
* @color: color to apply to node, if this node is not from a VMA,
* color must be #I915_COLOR_UNEVICTABLE
* @flags: control search and eviction behaviour
*
* i915_gem_gtt_reserve() tries to insert the @node at the exact @offset inside
* the address space (using @size and @color). If the @node does not fit, it
* tries to evict any overlapping nodes from the GTT, including any
* neighbouring nodes if the colors do not match (to ensure guard pages between
* differing domains). See i915_gem_evict_for_node() for the gory details
* on the eviction algorithm. #PIN_NONBLOCK may used to prevent waiting on
* evicting active overlapping objects, and any overlapping node that is pinned
* or marked as unevictable will also result in failure.
*
* Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
* asked to wait for eviction and interrupted.
*/
int i915_gem_gtt_reserve(struct i915_address_space *vm,
struct drm_mm_node *node,
u64 size, u64 offset, unsigned long color,
unsigned int flags)
{
int err;
GEM_BUG_ON(!size);
GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
GEM_BUG_ON(!IS_ALIGNED(offset, I915_GTT_MIN_ALIGNMENT));
GEM_BUG_ON(range_overflows(offset, size, vm->total));
GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm);
GEM_BUG_ON(drm_mm_node_allocated(node));
node->size = size;
node->start = offset;
node->color = color;
err = drm_mm_reserve_node(&vm->mm, node);
if (err != -ENOSPC)
return err;
if (flags & PIN_NOEVICT)
return -ENOSPC;
err = i915_gem_evict_for_node(vm, node, flags);
if (err == 0)
err = drm_mm_reserve_node(&vm->mm, node);
return err;
}
static u64 random_offset(u64 start, u64 end, u64 len, u64 align)
{
u64 range, addr;
GEM_BUG_ON(range_overflows(start, len, end));
GEM_BUG_ON(round_up(start, align) > round_down(end - len, align));
range = round_down(end - len, align) - round_up(start, align);
if (range) {
if (sizeof(unsigned long) == sizeof(u64)) {
addr = get_random_long();
} else {
addr = get_random_int();
if (range > U32_MAX) {
addr <<= 32;
addr |= get_random_int();
}
}
div64_u64_rem(addr, range, &addr);
start += addr;
}
return round_up(start, align);
}
/**
* i915_gem_gtt_insert - insert a node into an address_space (GTT)
* @vm: the &struct i915_address_space
* @node: the &struct drm_mm_node (typically i915_vma.node)
* @size: how much space to allocate inside the GTT,
* must be #I915_GTT_PAGE_SIZE aligned
* @alignment: required alignment of starting offset, may be 0 but
* if specified, this must be a power-of-two and at least
* #I915_GTT_MIN_ALIGNMENT
* @color: color to apply to node
* @start: start of any range restriction inside GTT (0 for all),
* must be #I915_GTT_PAGE_SIZE aligned
* @end: end of any range restriction inside GTT (U64_MAX for all),
* must be #I915_GTT_PAGE_SIZE aligned if not U64_MAX
* @flags: control search and eviction behaviour
*
* i915_gem_gtt_insert() first searches for an available hole into which
* is can insert the node. The hole address is aligned to @alignment and
* its @size must then fit entirely within the [@start, @end] bounds. The
* nodes on either side of the hole must match @color, or else a guard page
* will be inserted between the two nodes (or the node evicted). If no
* suitable hole is found, first a victim is randomly selected and tested
* for eviction, otherwise then the LRU list of objects within the GTT
* is scanned to find the first set of replacement nodes to create the hole.
* Those old overlapping nodes are evicted from the GTT (and so must be
* rebound before any future use). Any node that is currently pinned cannot
* be evicted (see i915_vma_pin()). Similar if the node's VMA is currently
* active and #PIN_NONBLOCK is specified, that node is also skipped when
* searching for an eviction candidate. See i915_gem_evict_something() for
* the gory details on the eviction algorithm.
*
* Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
* asked to wait for eviction and interrupted.
*/
int i915_gem_gtt_insert(struct i915_address_space *vm,
struct drm_mm_node *node,
u64 size, u64 alignment, unsigned long color,
u64 start, u64 end, unsigned int flags)
{
enum drm_mm_insert_mode mode;
u64 offset;
int err;
lockdep_assert_held(&vm->mutex);
GEM_BUG_ON(!size);
GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
GEM_BUG_ON(alignment && !is_power_of_2(alignment));
GEM_BUG_ON(alignment && !IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
GEM_BUG_ON(start >= end);
GEM_BUG_ON(start > 0 && !IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
GEM_BUG_ON(end < U64_MAX && !IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm);
GEM_BUG_ON(drm_mm_node_allocated(node));
if (unlikely(range_overflows(start, size, end)))
return -ENOSPC;
if (unlikely(round_up(start, alignment) > round_down(end - size, alignment)))
return -ENOSPC;
mode = DRM_MM_INSERT_BEST;
if (flags & PIN_HIGH)
mode = DRM_MM_INSERT_HIGHEST;
if (flags & PIN_MAPPABLE)
mode = DRM_MM_INSERT_LOW;
/* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
* so we know that we always have a minimum alignment of 4096.
* The drm_mm range manager is optimised to return results
* with zero alignment, so where possible use the optimal
* path.
*/
BUILD_BUG_ON(I915_GTT_MIN_ALIGNMENT > I915_GTT_PAGE_SIZE);
if (alignment <= I915_GTT_MIN_ALIGNMENT)
alignment = 0;
err = drm_mm_insert_node_in_range(&vm->mm, node,
size, alignment, color,
start, end, mode);
if (err != -ENOSPC)
return err;
if (mode & DRM_MM_INSERT_ONCE) {
err = drm_mm_insert_node_in_range(&vm->mm, node,
size, alignment, color,
start, end,
DRM_MM_INSERT_BEST);
if (err != -ENOSPC)
return err;
}
if (flags & PIN_NOEVICT)
return -ENOSPC;
/*
* No free space, pick a slot at random.
*
* There is a pathological case here using a GTT shared between
* mmap and GPU (i.e. ggtt/aliasing_ppgtt but not full-ppgtt):
*
* |<-- 256 MiB aperture -->||<-- 1792 MiB unmappable -->|
* (64k objects) (448k objects)
*
* Now imagine that the eviction LRU is ordered top-down (just because
* pathology meets real life), and that we need to evict an object to
* make room inside the aperture. The eviction scan then has to walk
* the 448k list before it finds one within range. And now imagine that
* it has to search for a new hole between every byte inside the memcpy,
* for several simultaneous clients.
*
* On a full-ppgtt system, if we have run out of available space, there
* will be lots and lots of objects in the eviction list! Again,
* searching that LRU list may be slow if we are also applying any
* range restrictions (e.g. restriction to low 4GiB) and so, for
* simplicity and similarilty between different GTT, try the single
* random replacement first.
*/
offset = random_offset(start, end,
size, alignment ?: I915_GTT_MIN_ALIGNMENT);
err = i915_gem_gtt_reserve(vm, node, size, offset, color, flags);
if (err != -ENOSPC)
return err;
if (flags & PIN_NOSEARCH)
return -ENOSPC;
/* Randomly selected placement is pinned, do a search */
err = i915_gem_evict_something(vm, size, alignment, color,
start, end, flags);
if (err)
return err;
return drm_mm_insert_node_in_range(&vm->mm, node,
size, alignment, color,
start, end, DRM_MM_INSERT_EVICT);
}
#if IS_ENABLED([31mCONFIG_DRM_I915_SELFTEST[0m)
#include "selftests/i915_gem_gtt.c"
#endif