path: root/drivers/gpu/nvgpu/common/mm/pd_cache.c

/*
 * Copyright (c) 2017, NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#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 "gk20a/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 basially just 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, the full and the partial. The full lists contain
 * pages of memory for which all the memory in that page is in use. The partial
 * lists contain partially full pages of memory which can be used for more PD
 * allocations. There a couple of assumptions here:
 *
 *   1. PDs greater than or equal to the page size bypass the pd cache.
 *   2. PDs are always power of 2 and greater than %NVGPU_PD_CACHE_MIN bytes.
 *
 * There are NVGPU_PD_CACHE_COUNT full lists and the same number of partial
 * lists. For a 4Kb page NVGPU_PD_CACHE_COUNT is 4. This is enough space for
 * 256, 512, 1024, and 2048 byte PDs.
 *
 * __nvgpu_pd_alloc() will allocate a PD for the GMMU. It will check if the PD
 * size is page 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 - 1));
}

static u32 nvgpu_pd_cache_get_mask(struct nvgpu_pd_mem_entry *pentry)
{
	u32 mask_offset = 1 << (PAGE_SIZE / pentry->pd_size);

	return mask_offset - 1;
}

int nvgpu_pd_cache_init(struct gk20a *g)
{
	struct nvgpu_pd_cache *cache;
	int i;

	/*
	 * 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) {
		nvgpu_err(g, "Failed to alloc pd_cache!");
		return -ENOMEM;
	}

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

	cache->mem_tree = NULL;
	g->mm.pd_cache = cache;
	nvgpu_mutex_init(&cache->lock);

	pd_dbg(g, "PD cache initialized!");

	return 0;
}

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

	if (!cache)
		return;

	for (i = 0; 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;

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

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

	err = nvgpu_dma_alloc(g, 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;

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

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

	if (nvgpu_dma_alloc(g, PAGE_SIZE, &pentry->mem)) {
		nvgpu_kfree(g, pentry);
		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.
	 */
	pentry->alloc_map = 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 pentry_mask = nvgpu_pd_cache_get_mask(pentry);

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

	/* Bit map full. Somethings wrong. */
	if (WARN_ON(bit_offs >= ffz(pentry_mask)))
		return -ENOMEM;

	pentry->alloc_map |= 1 << bit_offs;

	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->alloc_map & pentry_mask) == pentry_mask) {
		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 - 1) ||
	    (bytes >= PAGE_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)
		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 a page so just do a regular DMA
	 * alloc.
	 */
	if (bytes >= PAGE_SIZE) {
		err = __nvgpu_pd_cache_alloc_direct(g, pd, bytes);
		if (err)
			return err;

		return 0;
	}

	if (WARN_ON(!g->mm.pd_cache))
		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)
		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 index = pd->mem_offs / pentry->pd_size;
	u32 bit = 1 << index;

	/* Mark entry as free. */
	pentry->alloc_map &= ~bit;

	if (pentry->alloc_map & nvgpu_pd_cache_get_mask(pentry)) {
		/*
		 * Partially full still. If it was already on the partial list
		 * this just re-adds it.
		 */
		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);
	}
}

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)
		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) {
		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);
}