18e17c662SQuentin Perret // SPDX-License-Identifier: GPL-2.0-only 28e17c662SQuentin Perret /* 38e17c662SQuentin Perret * Copyright (C) 2020 Google LLC 48e17c662SQuentin Perret * Author: Quentin Perret <qperret@google.com> 58e17c662SQuentin Perret */ 68e17c662SQuentin Perret 78e17c662SQuentin Perret #include <asm/kvm_hyp.h> 88e17c662SQuentin Perret #include <nvhe/gfp.h> 98e17c662SQuentin Perret 108e17c662SQuentin Perret u64 __hyp_vmemmap; 118e17c662SQuentin Perret 128e17c662SQuentin Perret /* 138e17c662SQuentin Perret * Index the hyp_vmemmap to find a potential buddy page, but make no assumption 148e17c662SQuentin Perret * about its current state. 158e17c662SQuentin Perret * 168e17c662SQuentin Perret * Example buddy-tree for a 4-pages physically contiguous pool: 178e17c662SQuentin Perret * 188e17c662SQuentin Perret * o : Page 3 198e17c662SQuentin Perret * / 208e17c662SQuentin Perret * o-o : Page 2 218e17c662SQuentin Perret * / 228e17c662SQuentin Perret * / o : Page 1 238e17c662SQuentin Perret * / / 248e17c662SQuentin Perret * o---o-o : Page 0 258e17c662SQuentin Perret * Order 2 1 0 268e17c662SQuentin Perret * 278e17c662SQuentin Perret * Example of requests on this pool: 288e17c662SQuentin Perret * __find_buddy_nocheck(pool, page 0, order 0) => page 1 298e17c662SQuentin Perret * __find_buddy_nocheck(pool, page 0, order 1) => page 2 308e17c662SQuentin Perret * __find_buddy_nocheck(pool, page 1, order 0) => page 0 318e17c662SQuentin Perret * __find_buddy_nocheck(pool, page 2, order 0) => page 3 328e17c662SQuentin Perret */ 338e17c662SQuentin Perret static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool, 348e17c662SQuentin Perret struct hyp_page *p, 358e17c662SQuentin Perret unsigned int order) 368e17c662SQuentin Perret { 378e17c662SQuentin Perret phys_addr_t addr = hyp_page_to_phys(p); 388e17c662SQuentin Perret 398e17c662SQuentin Perret addr ^= (PAGE_SIZE << order); 408e17c662SQuentin Perret 418e17c662SQuentin Perret /* 428e17c662SQuentin Perret * Don't return a page outside the pool range -- it belongs to 438e17c662SQuentin Perret * something else and may not be mapped in hyp_vmemmap. 448e17c662SQuentin Perret */ 458e17c662SQuentin Perret if (addr < pool->range_start || addr >= pool->range_end) 468e17c662SQuentin Perret return NULL; 478e17c662SQuentin Perret 488e17c662SQuentin Perret return hyp_phys_to_page(addr); 498e17c662SQuentin Perret } 508e17c662SQuentin Perret 518e17c662SQuentin Perret /* Find a buddy page currently available for allocation */ 528e17c662SQuentin Perret static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool, 538e17c662SQuentin Perret struct hyp_page *p, 548e17c662SQuentin Perret unsigned int order) 558e17c662SQuentin Perret { 568e17c662SQuentin Perret struct hyp_page *buddy = __find_buddy_nocheck(pool, p, order); 578e17c662SQuentin Perret 588e17c662SQuentin Perret if (!buddy || buddy->order != order || list_empty(&buddy->node)) 598e17c662SQuentin Perret return NULL; 608e17c662SQuentin Perret 618e17c662SQuentin Perret return buddy; 628e17c662SQuentin Perret 638e17c662SQuentin Perret } 648e17c662SQuentin Perret 658e17c662SQuentin Perret static void __hyp_attach_page(struct hyp_pool *pool, 668e17c662SQuentin Perret struct hyp_page *p) 678e17c662SQuentin Perret { 688e17c662SQuentin Perret unsigned int order = p->order; 698e17c662SQuentin Perret struct hyp_page *buddy; 708e17c662SQuentin Perret 718e17c662SQuentin Perret memset(hyp_page_to_virt(p), 0, PAGE_SIZE << p->order); 728e17c662SQuentin Perret 738e17c662SQuentin Perret /* 748e17c662SQuentin Perret * Only the first struct hyp_page of a high-order page (otherwise known 758e17c662SQuentin Perret * as the 'head') should have p->order set. The non-head pages should 768e17c662SQuentin Perret * have p->order = HYP_NO_ORDER. Here @p may no longer be the head 778e17c662SQuentin Perret * after coallescing, so make sure to mark it HYP_NO_ORDER proactively. 788e17c662SQuentin Perret */ 798e17c662SQuentin Perret p->order = HYP_NO_ORDER; 808e17c662SQuentin Perret for (; (order + 1) < pool->max_order; order++) { 818e17c662SQuentin Perret buddy = __find_buddy_avail(pool, p, order); 828e17c662SQuentin Perret if (!buddy) 838e17c662SQuentin Perret break; 848e17c662SQuentin Perret 858e17c662SQuentin Perret /* Take the buddy out of its list, and coallesce with @p */ 868e17c662SQuentin Perret list_del_init(&buddy->node); 878e17c662SQuentin Perret buddy->order = HYP_NO_ORDER; 888e17c662SQuentin Perret p = min(p, buddy); 898e17c662SQuentin Perret } 908e17c662SQuentin Perret 918e17c662SQuentin Perret /* Mark the new head, and insert it */ 928e17c662SQuentin Perret p->order = order; 938e17c662SQuentin Perret list_add_tail(&p->node, &pool->free_area[order]); 948e17c662SQuentin Perret } 958e17c662SQuentin Perret 968e17c662SQuentin Perret static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool, 978e17c662SQuentin Perret struct hyp_page *p, 988e17c662SQuentin Perret unsigned int order) 998e17c662SQuentin Perret { 1008e17c662SQuentin Perret struct hyp_page *buddy; 1018e17c662SQuentin Perret 1028e17c662SQuentin Perret list_del_init(&p->node); 1038e17c662SQuentin Perret while (p->order > order) { 1048e17c662SQuentin Perret /* 1058e17c662SQuentin Perret * The buddy of order n - 1 currently has HYP_NO_ORDER as it 1068e17c662SQuentin Perret * is covered by a higher-level page (whose head is @p). Use 1078e17c662SQuentin Perret * __find_buddy_nocheck() to find it and inject it in the 1088e17c662SQuentin Perret * free_list[n - 1], effectively splitting @p in half. 1098e17c662SQuentin Perret */ 1108e17c662SQuentin Perret p->order--; 1118e17c662SQuentin Perret buddy = __find_buddy_nocheck(pool, p, p->order); 1128e17c662SQuentin Perret buddy->order = p->order; 1138e17c662SQuentin Perret list_add_tail(&buddy->node, &pool->free_area[buddy->order]); 1148e17c662SQuentin Perret } 1158e17c662SQuentin Perret 1168e17c662SQuentin Perret return p; 1178e17c662SQuentin Perret } 1188e17c662SQuentin Perret 119*6cbf874eSQuentin Perret static inline void hyp_page_ref_inc(struct hyp_page *p) 120*6cbf874eSQuentin Perret { 121*6cbf874eSQuentin Perret p->refcount++; 122*6cbf874eSQuentin Perret } 123*6cbf874eSQuentin Perret 124*6cbf874eSQuentin Perret static inline int hyp_page_ref_dec_and_test(struct hyp_page *p) 125*6cbf874eSQuentin Perret { 126*6cbf874eSQuentin Perret p->refcount--; 127*6cbf874eSQuentin Perret return (p->refcount == 0); 128*6cbf874eSQuentin Perret } 129*6cbf874eSQuentin Perret 130*6cbf874eSQuentin Perret static inline void hyp_set_page_refcounted(struct hyp_page *p) 131*6cbf874eSQuentin Perret { 132*6cbf874eSQuentin Perret BUG_ON(p->refcount); 133*6cbf874eSQuentin Perret p->refcount = 1; 134*6cbf874eSQuentin Perret } 135*6cbf874eSQuentin Perret 136*6cbf874eSQuentin Perret /* 137*6cbf874eSQuentin Perret * Changes to the buddy tree and page refcounts must be done with the hyp_pool 138*6cbf874eSQuentin Perret * lock held. If a refcount change requires an update to the buddy tree (e.g. 139*6cbf874eSQuentin Perret * hyp_put_page()), both operations must be done within the same critical 140*6cbf874eSQuentin Perret * section to guarantee transient states (e.g. a page with null refcount but 141*6cbf874eSQuentin Perret * not yet attached to a free list) can't be observed by well-behaved readers. 142*6cbf874eSQuentin Perret */ 1438e17c662SQuentin Perret void hyp_put_page(void *addr) 1448e17c662SQuentin Perret { 1458e17c662SQuentin Perret struct hyp_page *p = hyp_virt_to_page(addr); 146*6cbf874eSQuentin Perret struct hyp_pool *pool = hyp_page_to_pool(p); 1478e17c662SQuentin Perret 148*6cbf874eSQuentin Perret hyp_spin_lock(&pool->lock); 1498e17c662SQuentin Perret if (hyp_page_ref_dec_and_test(p)) 150*6cbf874eSQuentin Perret __hyp_attach_page(pool, p); 151*6cbf874eSQuentin Perret hyp_spin_unlock(&pool->lock); 1528e17c662SQuentin Perret } 1538e17c662SQuentin Perret 1548e17c662SQuentin Perret void hyp_get_page(void *addr) 1558e17c662SQuentin Perret { 1568e17c662SQuentin Perret struct hyp_page *p = hyp_virt_to_page(addr); 157*6cbf874eSQuentin Perret struct hyp_pool *pool = hyp_page_to_pool(p); 1588e17c662SQuentin Perret 159*6cbf874eSQuentin Perret hyp_spin_lock(&pool->lock); 1608e17c662SQuentin Perret hyp_page_ref_inc(p); 161*6cbf874eSQuentin Perret hyp_spin_unlock(&pool->lock); 1628e17c662SQuentin Perret } 1638e17c662SQuentin Perret 1648e17c662SQuentin Perret void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order) 1658e17c662SQuentin Perret { 1668e17c662SQuentin Perret unsigned int i = order; 1678e17c662SQuentin Perret struct hyp_page *p; 1688e17c662SQuentin Perret 1698e17c662SQuentin Perret hyp_spin_lock(&pool->lock); 1708e17c662SQuentin Perret 1718e17c662SQuentin Perret /* Look for a high-enough-order page */ 1728e17c662SQuentin Perret while (i < pool->max_order && list_empty(&pool->free_area[i])) 1738e17c662SQuentin Perret i++; 1748e17c662SQuentin Perret if (i >= pool->max_order) { 1758e17c662SQuentin Perret hyp_spin_unlock(&pool->lock); 1768e17c662SQuentin Perret return NULL; 1778e17c662SQuentin Perret } 1788e17c662SQuentin Perret 1798e17c662SQuentin Perret /* Extract it from the tree at the right order */ 1808e17c662SQuentin Perret p = list_first_entry(&pool->free_area[i], struct hyp_page, node); 1818e17c662SQuentin Perret p = __hyp_extract_page(pool, p, order); 1828e17c662SQuentin Perret 1838e17c662SQuentin Perret hyp_set_page_refcounted(p); 184*6cbf874eSQuentin Perret hyp_spin_unlock(&pool->lock); 1858e17c662SQuentin Perret 1868e17c662SQuentin Perret return hyp_page_to_virt(p); 1878e17c662SQuentin Perret } 1888e17c662SQuentin Perret 1898e17c662SQuentin Perret int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages, 1908e17c662SQuentin Perret unsigned int reserved_pages) 1918e17c662SQuentin Perret { 1928e17c662SQuentin Perret phys_addr_t phys = hyp_pfn_to_phys(pfn); 1938e17c662SQuentin Perret struct hyp_page *p; 1948e17c662SQuentin Perret int i; 1958e17c662SQuentin Perret 1968e17c662SQuentin Perret hyp_spin_lock_init(&pool->lock); 1978e17c662SQuentin Perret pool->max_order = min(MAX_ORDER, get_order(nr_pages << PAGE_SHIFT)); 1988e17c662SQuentin Perret for (i = 0; i < pool->max_order; i++) 1998e17c662SQuentin Perret INIT_LIST_HEAD(&pool->free_area[i]); 2008e17c662SQuentin Perret pool->range_start = phys; 2018e17c662SQuentin Perret pool->range_end = phys + (nr_pages << PAGE_SHIFT); 2028e17c662SQuentin Perret 2038e17c662SQuentin Perret /* Init the vmemmap portion */ 2048e17c662SQuentin Perret p = hyp_phys_to_page(phys); 2058e17c662SQuentin Perret memset(p, 0, sizeof(*p) * nr_pages); 2068e17c662SQuentin Perret for (i = 0; i < nr_pages; i++) { 2078e17c662SQuentin Perret p[i].pool = pool; 2088e17c662SQuentin Perret INIT_LIST_HEAD(&p[i].node); 2098e17c662SQuentin Perret } 2108e17c662SQuentin Perret 2118e17c662SQuentin Perret /* Attach the unused pages to the buddy tree */ 2128e17c662SQuentin Perret for (i = reserved_pages; i < nr_pages; i++) 2138e17c662SQuentin Perret __hyp_attach_page(pool, &p[i]); 2148e17c662SQuentin Perret 2158e17c662SQuentin Perret return 0; 2168e17c662SQuentin Perret } 217