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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 Google LLC
* Author: Quentin Perret <qperret@google.com>
*/
#include <asm/kvm_hyp.h>
#include <nvhe/gfp.h>
u64 __hyp_vmemmap;
/*
* Index the hyp_vmemmap to find a potential buddy page, but make no assumption
* about its current state.
*
* Example buddy-tree for a 4-pages physically contiguous pool:
*
* o : Page 3
* /
* o-o : Page 2
* /
* / o : Page 1
* / /
* o---o-o : Page 0
* Order 2 1 0
*
* Example of requests on this pool:
* __find_buddy_nocheck(pool, page 0, order 0) => page 1
* __find_buddy_nocheck(pool, page 0, order 1) => page 2
* __find_buddy_nocheck(pool, page 1, order 0) => page 0
* __find_buddy_nocheck(pool, page 2, order 0) => page 3
*/
static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool,
struct hyp_page *p,
unsigned int order)
{
phys_addr_t addr = hyp_page_to_phys(p);
addr ^= (PAGE_SIZE << order);
/*
* Don't return a page outside the pool range -- it belongs to
* something else and may not be mapped in hyp_vmemmap.
*/
if (addr < pool->range_start || addr >= pool->range_end)
return NULL;
return hyp_phys_to_page(addr);
}
/* Find a buddy page currently available for allocation */
static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool,
struct hyp_page *p,
unsigned int order)
{
struct hyp_page *buddy = __find_buddy_nocheck(pool, p, order);
if (!buddy || buddy->order != order || list_empty(&buddy->node))
return NULL;
return buddy;
}
static void __hyp_attach_page(struct hyp_pool *pool,
struct hyp_page *p)
{
unsigned int order = p->order;
struct hyp_page *buddy;
memset(hyp_page_to_virt(p), 0, PAGE_SIZE << p->order);
/*
* Only the first struct hyp_page of a high-order page (otherwise known
* as the 'head') should have p->order set. The non-head pages should
* have p->order = HYP_NO_ORDER. Here @p may no longer be the head
* after coallescing, so make sure to mark it HYP_NO_ORDER proactively.
*/
p->order = HYP_NO_ORDER;
for (; (order + 1) < pool->max_order; order++) {
buddy = __find_buddy_avail(pool, p, order);
if (!buddy)
break;
/* Take the buddy out of its list, and coallesce with @p */
list_del_init(&buddy->node);
buddy->order = HYP_NO_ORDER;
p = min(p, buddy);
}
/* Mark the new head, and insert it */
p->order = order;
list_add_tail(&p->node, &pool->free_area[order]);
}
static void hyp_attach_page(struct hyp_page *p)
{
struct hyp_pool *pool = hyp_page_to_pool(p);
hyp_spin_lock(&pool->lock);
__hyp_attach_page(pool, p);
hyp_spin_unlock(&pool->lock);
}
static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
struct hyp_page *p,
unsigned int order)
{
struct hyp_page *buddy;
list_del_init(&p->node);
while (p->order > order) {
/*
* The buddy of order n - 1 currently has HYP_NO_ORDER as it
* is covered by a higher-level page (whose head is @p). Use
* __find_buddy_nocheck() to find it and inject it in the
* free_list[n - 1], effectively splitting @p in half.
*/
p->order--;
buddy = __find_buddy_nocheck(pool, p, p->order);
buddy->order = p->order;
list_add_tail(&buddy->node, &pool->free_area[buddy->order]);
}
return p;
}
void hyp_put_page(void *addr)
{
struct hyp_page *p = hyp_virt_to_page(addr);
if (hyp_page_ref_dec_and_test(p))
hyp_attach_page(p);
}
void hyp_get_page(void *addr)
{
struct hyp_page *p = hyp_virt_to_page(addr);
hyp_page_ref_inc(p);
}
void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order)
{
unsigned int i = order;
struct hyp_page *p;
hyp_spin_lock(&pool->lock);
/* Look for a high-enough-order page */
while (i < pool->max_order && list_empty(&pool->free_area[i]))
i++;
if (i >= pool->max_order) {
hyp_spin_unlock(&pool->lock);
return NULL;
}
/* Extract it from the tree at the right order */
p = list_first_entry(&pool->free_area[i], struct hyp_page, node);
p = __hyp_extract_page(pool, p, order);
hyp_spin_unlock(&pool->lock);
hyp_set_page_refcounted(p);
return hyp_page_to_virt(p);
}
int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages,
unsigned int reserved_pages)
{
phys_addr_t phys = hyp_pfn_to_phys(pfn);
struct hyp_page *p;
int i;
hyp_spin_lock_init(&pool->lock);
pool->max_order = min(MAX_ORDER, get_order(nr_pages << PAGE_SHIFT));
for (i = 0; i < pool->max_order; i++)
INIT_LIST_HEAD(&pool->free_area[i]);
pool->range_start = phys;
pool->range_end = phys + (nr_pages << PAGE_SHIFT);
/* Init the vmemmap portion */
p = hyp_phys_to_page(phys);
memset(p, 0, sizeof(*p) * nr_pages);
for (i = 0; i < nr_pages; i++) {
p[i].pool = pool;
INIT_LIST_HEAD(&p[i].node);
}
/* Attach the unused pages to the buddy tree */
for (i = reserved_pages; i < nr_pages; i++)
__hyp_attach_page(pool, &p[i]);
return 0;
}
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