linux-nvgpu/drivers/gpu/nvgpu/common/mm/pd_cache.c

/*
 * Copyright (c) 2017-2020, NVIDIA CORPORATION.  All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <nvgpu/bug.h>
#include <nvgpu/log.h>
#include <nvgpu/dma.h>
#include <nvgpu/gmmu.h>
#include <nvgpu/nvgpu_mem.h>
#include <nvgpu/list.h>
#include <nvgpu/log2.h>
#include <nvgpu/gk20a.h>

#include "gk20a/mm_gk20a.h"

#define pd_dbg(g, fmt, args...) nvgpu_log(g, gpu_dbg_pd_cache, fmt, ##args)

/**
 * DOC: PD cache
 *
 * In the name of saving memory with the many sub-page sized PD levels in Pascal
 * and beyond a way of packing PD tables together is necessary. This code here
 * does just that. If a PD table only requires 1024 bytes, then it is possible
 * to have 4 of these PDs in one page. This is even more pronounced for 256 byte
 * PD tables.
 *
 * The pd cache is basically a slab allocator. Each instance of the nvgpu
 * driver makes one of these structs:
 *
 *   struct nvgpu_pd_cache {
 *      struct nvgpu_list_node		 full[NVGPU_PD_CACHE_COUNT];
 *      struct nvgpu_list_node		 partial[NVGPU_PD_CACHE_COUNT];
 *
 *      struct nvgpu_rbtree_node	*mem_tree;
 *   };
 *
 * There are two sets of lists used for cached allocations, the full and the
 * partial. The full lists contain pages of memory for which all the memory in
 * that entry is in use. The partial lists contain partially full blocks of
 * memory which can be used for more PD allocations. The cache works as follows:
 *
 *   1. PDs greater than NVGPU_PD_CACHE_SIZE bypass the pd cache.
 *   2. PDs are always power of 2 and greater than %NVGPU_PD_CACHE_MIN bytes.
 *
 * nvgpu_pd_alloc() will allocate a PD for the GMMU. It will check if the PD
 * size is NVGPU_PD_CACHE_SIZE or larger and choose the correct allocation
 * scheme - either from the PD cache or directly. Similarly nvgpu_pd_free()
 * will free a PD allocated by nvgpu_pd_alloc().
 *
 * Since the top level PD (the PDB) is a page aligned pointer but less than a
 * page size the direct functions must be used for allocating PDBs. Otherwise
 * there would be alignment issues for the PDBs when they get packed.
 */

static u32 nvgpu_pd_cache_nr(u32 bytes)
{
	return ilog2(bytes >> (NVGPU_PD_CACHE_MIN_SHIFT - 1U));
}

static u32 nvgpu_pd_cache_get_nr_entries(struct nvgpu_pd_mem_entry *pentry)
{
	BUG_ON(pentry->pd_size == 0);

	return NVGPU_PD_CACHE_SIZE / pentry->pd_size;
}

int nvgpu_pd_cache_init(struct gk20a *g)
{
	struct nvgpu_pd_cache *cache;
	u32 i;
	int err = 0;


	/*
	 * This gets called from finalize_poweron() so we need to make sure we
	 * don't reinit the pd_cache over and over.
	 */
	if (g->mm.pd_cache) {
		return 0;
	}

	cache = nvgpu_kzalloc(g, sizeof(*cache));
	if (cache == NULL) {
		nvgpu_err(g, "Failed to alloc pd_cache!");
		return -ENOMEM;
	}

	for (i = 0U; i < NVGPU_PD_CACHE_COUNT; i++) {
		nvgpu_init_list_node(&cache->full[i]);
		nvgpu_init_list_node(&cache->partial[i]);
	}

	cache->mem_tree = NULL;

	err = nvgpu_mutex_init(&cache->lock);
	if (err != 0) {
		nvgpu_err(g, "Error in cache.lock initialization");
		nvgpu_kfree(g, cache);
		return err;
	}

	g->mm.pd_cache = cache;
	pd_dbg(g, "PD cache initialized!");

	return 0;
}

void nvgpu_pd_cache_fini(struct gk20a *g)
{
	u32 i;
	struct nvgpu_pd_cache *cache = g->mm.pd_cache;

	if (cache == NULL) {
		return;
	}

	for (i = 0U; i < NVGPU_PD_CACHE_COUNT; i++) {
		WARN_ON(!nvgpu_list_empty(&cache->full[i]));
		WARN_ON(!nvgpu_list_empty(&cache->partial[i]));
	}

	nvgpu_kfree(g, g->mm.pd_cache);
}

/*
 * This is the simple pass-through for greater than page or page sized PDs.
 *
 * Note: this does not need the cache lock since it does not modify any of the
 * PD cache data structures.
 */
int nvgpu_pd_cache_alloc_direct(struct gk20a *g,
				struct nvgpu_gmmu_pd *pd, u32 bytes)
{
	int err;
	unsigned long flags = 0;

	pd_dbg(g, "PD-Alloc [D] %u bytes", bytes);

	pd->mem = nvgpu_kzalloc(g, sizeof(*pd->mem));
	if (pd->mem == NULL) {
		nvgpu_err(g, "OOM allocating nvgpu_mem struct!");
		return -ENOMEM;
	}

	/*
	 * If bytes == PAGE_SIZE then it's impossible to get a discontiguous DMA
	 * allocation. Some DMA implementations may, despite this fact, still
	 * use the contiguous pool for page sized allocations. As such only
	 * request explicitly contiguous allocs if the page directory is larger
	 * than the page size. Also, of course, this is all only revelant for
	 * GPUs not using an IOMMU. If there is an IOMMU DMA allocs are always
	 * going to be virtually contiguous and we don't have to force the
	 * underlying allocations to be physically contiguous as well.
	 */
	if (!nvgpu_iommuable(g) && bytes > PAGE_SIZE) {
		flags = NVGPU_DMA_FORCE_CONTIGUOUS;
	}

	err = nvgpu_dma_alloc_flags(g, flags, bytes, pd->mem);
	if (err) {
		nvgpu_err(g, "OOM allocating page directory!");
		nvgpu_kfree(g, pd->mem);
		return -ENOMEM;
	}

	pd->cached = false;
	pd->mem_offs = 0;

	return 0;
}

/*
 * Make a new nvgpu_pd_cache_entry and allocate a PD from it. Update the passed
 * pd to reflect this allocation.
 */
static int nvgpu_pd_cache_alloc_new(struct gk20a *g,
				    struct nvgpu_pd_cache *cache,
				    struct nvgpu_gmmu_pd *pd,
				    u32 bytes)
{
	struct nvgpu_pd_mem_entry *pentry;
	unsigned long flags = 0;
	int err;

	pd_dbg(g, "PD-Alloc [C]   New: offs=0");

	pentry = nvgpu_kzalloc(g, sizeof(*pentry));
	if (pentry == NULL) {
		nvgpu_err(g, "OOM allocating pentry!");
		return -ENOMEM;
	}

	if (!nvgpu_iommuable(g) && (NVGPU_PD_CACHE_SIZE > PAGE_SIZE)) {
		flags = NVGPU_DMA_FORCE_CONTIGUOUS;
	}

	err = nvgpu_dma_alloc_flags(g, flags,
				    NVGPU_PD_CACHE_SIZE, &pentry->mem);
	if (err != 0) {
		nvgpu_kfree(g, pentry);

		/* Not enough contiguous space, but a direct
		 * allocation may work
		 */
		if (err == -ENOMEM) {
			return nvgpu_pd_cache_alloc_direct(g, pd, bytes);
		}
		nvgpu_err(g, "Unable to DMA alloc!");
		return -ENOMEM;
	}

	pentry->pd_size = bytes;
	nvgpu_list_add(&pentry->list_entry,
		       &cache->partial[nvgpu_pd_cache_nr(bytes)]);

	/*
	 * This allocates the very first PD table in the set of tables in this
	 * nvgpu_pd_mem_entry.
	 */
	set_bit(0U, pentry->alloc_map);
	pentry->allocs = 1;

	/*
	 * Now update the nvgpu_gmmu_pd to reflect this allocation.
	 */
	pd->mem = &pentry->mem;
	pd->mem_offs = 0;
	pd->cached = true;

	pentry->tree_entry.key_start = (u64)(uintptr_t)&pentry->mem;
	nvgpu_rbtree_insert(&pentry->tree_entry, &cache->mem_tree);

	return 0;
}

static int nvgpu_pd_cache_alloc_from_partial(struct gk20a *g,
					     struct nvgpu_pd_cache *cache,
					     struct nvgpu_pd_mem_entry *pentry,
					     struct nvgpu_gmmu_pd *pd)
{
	unsigned long bit_offs;
	u32 mem_offs;
	u32 nr_bits = nvgpu_pd_cache_get_nr_entries(pentry);

	/*
	 * Find and allocate an open PD.
	 */
	bit_offs = find_first_zero_bit(pentry->alloc_map, nr_bits);
	mem_offs = bit_offs * pentry->pd_size;

	/* Bit map full. Somethings wrong. */
	if (WARN_ON(bit_offs >= nr_bits)) {
		return -ENOMEM;
	}

	set_bit(bit_offs, pentry->alloc_map);
	pentry->allocs++;

	pd_dbg(g, "PD-Alloc [C]   Partial: offs=%lu", bit_offs);

	/*
	 * First update the pd.
	 */
	pd->mem = &pentry->mem;
	pd->mem_offs = mem_offs;
	pd->cached = true;

	/*
	 * Now make sure the pentry is in the correct list (full vs partial).
	 */
	if (pentry->allocs >= nr_bits) {
		pd_dbg(g, "Adding pentry to full list!");
		nvgpu_list_del(&pentry->list_entry);
		nvgpu_list_add(&pentry->list_entry,
			&cache->full[nvgpu_pd_cache_nr(pentry->pd_size)]);
	}

	return 0;
}

/*
 * Get a partially full nvgpu_pd_mem_entry. Returns NULL if there is no partial
 * nvgpu_pd_mem_entry's.
 */
static struct nvgpu_pd_mem_entry *nvgpu_pd_cache_get_partial(
	struct nvgpu_pd_cache *cache, u32 bytes)
{
	struct nvgpu_list_node *list =
		&cache->partial[nvgpu_pd_cache_nr(bytes)];

	if (nvgpu_list_empty(list)) {
		return NULL;
	}

	return nvgpu_list_first_entry(list,
				      nvgpu_pd_mem_entry,
				      list_entry);
}

/*
 * Allocate memory from an nvgpu_mem for the page directory.
 */
static int nvgpu_pd_cache_alloc(struct gk20a *g, struct nvgpu_pd_cache *cache,
				struct nvgpu_gmmu_pd *pd, u32 bytes)
{
	struct nvgpu_pd_mem_entry *pentry;
	int err;

	pd_dbg(g, "PD-Alloc [C] %u bytes", bytes);

	if ((bytes & (bytes - 1U)) != 0U ||
	    (bytes >= NVGPU_PD_CACHE_SIZE ||
	     bytes < NVGPU_PD_CACHE_MIN)) {
		pd_dbg(g, "PD-Alloc [C]   Invalid (bytes=%u)!", bytes);
		return -EINVAL;
	}

	pentry = nvgpu_pd_cache_get_partial(cache, bytes);
	if (pentry == NULL) {
		err = nvgpu_pd_cache_alloc_new(g, cache, pd, bytes);
	} else {
		err = nvgpu_pd_cache_alloc_from_partial(g, cache, pentry, pd);
	}

	if (err) {
		nvgpu_err(g, "PD-Alloc [C] Failed!");
	}

	return err;
}

/*
 * Allocate the DMA memory for a page directory. This handles the necessary PD
 * cache logistics. Since on Parker and later GPUs some of the page  directories
 * are smaller than a page packing these PDs together saves a lot of memory.
 */
int nvgpu_pd_alloc(struct vm_gk20a *vm,
		   struct nvgpu_gmmu_pd *pd,
		   u32 bytes)
{
	struct gk20a *g = gk20a_from_vm(vm);
	int err;

	/*
	 * Simple case: PD is bigger than or equal to NVGPU_PD_CACHE_SIZE so
	 * just do a regular DMA alloc.
	 */
	if (bytes >= NVGPU_PD_CACHE_SIZE) {
		err = nvgpu_pd_cache_alloc_direct(g, pd, bytes);
		if (err) {
			return err;
		}

		return 0;
	}

	if (WARN_ON(g->mm.pd_cache == NULL)) {
		return -ENOMEM;
	}

	nvgpu_mutex_acquire(&g->mm.pd_cache->lock);
	err = nvgpu_pd_cache_alloc(g, g->mm.pd_cache, pd, bytes);
	nvgpu_mutex_release(&g->mm.pd_cache->lock);

	return err;
}

void nvgpu_pd_cache_free_direct(struct gk20a *g, struct nvgpu_gmmu_pd *pd)
{
	pd_dbg(g, "PD-Free  [D] 0x%p", pd->mem);

	if (pd->mem == NULL) {
		return;
	}

	nvgpu_dma_free(g, pd->mem);
	nvgpu_kfree(g, pd->mem);
	pd->mem = NULL;
}

static void nvgpu_pd_cache_free_mem_entry(struct gk20a *g,
					  struct nvgpu_pd_cache *cache,
					  struct nvgpu_pd_mem_entry *pentry)
{
	nvgpu_dma_free(g, &pentry->mem);
	nvgpu_list_del(&pentry->list_entry);
	nvgpu_rbtree_unlink(&pentry->tree_entry, &cache->mem_tree);
	nvgpu_kfree(g, pentry);
}

static void nvgpu_pd_cache_do_free(struct gk20a *g,
				   struct nvgpu_pd_cache *cache,
				   struct nvgpu_pd_mem_entry *pentry,
				   struct nvgpu_gmmu_pd *pd)
{
	u32 bit = pd->mem_offs / pentry->pd_size;

	/* Mark entry as free. */
	clear_bit(bit, pentry->alloc_map);
	pentry->allocs--;

	if (pentry->allocs > 0U) {
		/*
		 * Partially full still. If it was already on the partial list
		 * this just re-adds it.
		 *
		 * Since the memory used for the entries is still mapped, if
		 * iommu is being used,  make sure PTE entries in particular
		 * are invalidated so that the hw doesn't accidentally try to
		 * prefetch non-existent fb memory.
		 *
		 * Notes:
		 *   - The check for NVGPU_PD_CACHE_SIZE > PAGE_SIZE effectively
		 *     determines whether PTE entries use the cache.
		 *   - In the case where PTE entries ues the cache, we also
		 *     end up invalidating the PDE entries, but that's a minor
		 *     performance hit, as there are far fewer of those
		 *     typically than there are PTE entries.
		 */
		if (nvgpu_iommuable(g) && (NVGPU_PD_CACHE_SIZE > PAGE_SIZE)) {
			memset((void *)((u64)pd->mem->cpu_va + pd->mem_offs), 0,
					pentry->pd_size);
		}

		nvgpu_list_del(&pentry->list_entry);
		nvgpu_list_add(&pentry->list_entry,
			&cache->partial[nvgpu_pd_cache_nr(pentry->pd_size)]);
	} else {
		/* Empty now so free it. */
		nvgpu_pd_cache_free_mem_entry(g, cache, pentry);
	}

	pd->mem = NULL;
}

static struct nvgpu_pd_mem_entry *nvgpu_pd_cache_look_up(
	struct gk20a *g,
	struct nvgpu_pd_cache *cache,
	struct nvgpu_gmmu_pd *pd)
{
	struct nvgpu_rbtree_node *node;

	nvgpu_rbtree_search((u64)(uintptr_t)pd->mem, &node,
			    cache->mem_tree);
	if (node == NULL) {
		return NULL;
	}

	return nvgpu_pd_mem_entry_from_tree_entry(node);
}

static void nvgpu_pd_cache_free(struct gk20a *g, struct nvgpu_pd_cache *cache,
				struct nvgpu_gmmu_pd *pd)
{
	struct nvgpu_pd_mem_entry *pentry;

	pd_dbg(g, "PD-Free  [C] 0x%p", pd->mem);

	pentry = nvgpu_pd_cache_look_up(g, cache, pd);
	if (pentry == NULL) {
		WARN(1, "Attempting to free non-existent pd");
		return;
	}

	nvgpu_pd_cache_do_free(g, cache, pentry, pd);
}

void nvgpu_pd_free(struct vm_gk20a *vm, struct nvgpu_gmmu_pd *pd)
{
	struct gk20a *g = gk20a_from_vm(vm);

	/*
	 * Simple case: just DMA free.
	 */
	if (!pd->cached) {
		return nvgpu_pd_cache_free_direct(g, pd);
	}

	nvgpu_mutex_acquire(&g->mm.pd_cache->lock);
	nvgpu_pd_cache_free(g, g->mm.pd_cache, pd);
	nvgpu_mutex_release(&g->mm.pd_cache->lock);
}