diff options
Diffstat (limited to 'arch/arm64/kvm/hyp/nvhe/page_alloc.c')
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/page_alloc.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c new file mode 100644 index 000000000000..237e03bf0cb1 --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c @@ -0,0 +1,195 @@ +// 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; +} |