diff options
Diffstat (limited to 'arch/powerpc/platforms/pseries/rtas-work-area.c')
| -rw-r--r-- | arch/powerpc/platforms/pseries/rtas-work-area.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/rtas-work-area.c b/arch/powerpc/platforms/pseries/rtas-work-area.c new file mode 100644 index 000000000000..7fe34bee84d8 --- /dev/null +++ b/arch/powerpc/platforms/pseries/rtas-work-area.c @@ -0,0 +1,210 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#define pr_fmt(fmt) "rtas-work-area: " fmt + +#include <linux/genalloc.h> +#include <linux/log2.h> +#include <linux/kernel.h> +#include <linux/memblock.h> +#include <linux/mempool.h> +#include <linux/minmax.h> +#include <linux/mutex.h> +#include <linux/numa.h> +#include <linux/sizes.h> +#include <linux/wait.h> + +#include <asm/machdep.h> +#include <asm/rtas-work-area.h> +#include <asm/rtas.h> + +enum { + /* + * Ensure the pool is page-aligned. + */ + RTAS_WORK_AREA_ARENA_ALIGN = PAGE_SIZE, + /* + * Don't let a single allocation claim the whole arena. + */ + RTAS_WORK_AREA_ARENA_SZ = RTAS_WORK_AREA_MAX_ALLOC_SZ * 2, + /* + * The smallest known work area size is for ibm,get-vpd's + * location code argument, which is limited to 79 characters + * plus 1 nul terminator. + * + * PAPR+ 7.3.20 ibm,get-vpd RTAS Call + * PAPR+ 12.3.2.4 Converged Location Code Rules - Length Restrictions + */ + RTAS_WORK_AREA_MIN_ALLOC_SZ = roundup_pow_of_two(80), +}; + +static struct { + struct gen_pool *gen_pool; + char *arena; + struct mutex mutex; /* serializes allocations */ + struct wait_queue_head wqh; + mempool_t descriptor_pool; + bool available; +} rwa_state = { + .mutex = __MUTEX_INITIALIZER(rwa_state.mutex), + .wqh = __WAIT_QUEUE_HEAD_INITIALIZER(rwa_state.wqh), +}; + +/* + * A single work area buffer and descriptor to serve requests early in + * boot before the allocator is fully initialized. We know 4KB is the + * most any boot time user needs (they all call ibm,get-system-parameter). + */ +static bool early_work_area_in_use __initdata; +static char early_work_area_buf[SZ_4K] __initdata __aligned(SZ_4K); +static struct rtas_work_area early_work_area __initdata = { + .buf = early_work_area_buf, + .size = sizeof(early_work_area_buf), +}; + + +static struct rtas_work_area * __init rtas_work_area_alloc_early(size_t size) +{ + WARN_ON(size > early_work_area.size); + WARN_ON(early_work_area_in_use); + early_work_area_in_use = true; + memset(early_work_area.buf, 0, early_work_area.size); + return &early_work_area; +} + +static void __init rtas_work_area_free_early(struct rtas_work_area *work_area) +{ + WARN_ON(work_area != &early_work_area); + WARN_ON(!early_work_area_in_use); + early_work_area_in_use = false; +} + +struct rtas_work_area * __ref __rtas_work_area_alloc(size_t size) +{ + struct rtas_work_area *area; + unsigned long addr; + + might_sleep(); + + /* + * The rtas_work_area_alloc() wrapper enforces this at build + * time. Requests that exceed the arena size will block + * indefinitely. + */ + WARN_ON(size > RTAS_WORK_AREA_MAX_ALLOC_SZ); + + if (!rwa_state.available) + return rtas_work_area_alloc_early(size); + /* + * To ensure FCFS behavior and prevent a high rate of smaller + * requests from starving larger ones, use the mutex to queue + * allocations. + */ + mutex_lock(&rwa_state.mutex); + wait_event(rwa_state.wqh, + (addr = gen_pool_alloc(rwa_state.gen_pool, size)) != 0); + mutex_unlock(&rwa_state.mutex); + + area = mempool_alloc(&rwa_state.descriptor_pool, GFP_KERNEL); + area->buf = (char *)addr; + area->size = size; + + return area; +} + +void __ref rtas_work_area_free(struct rtas_work_area *area) +{ + if (!rwa_state.available) { + rtas_work_area_free_early(area); + return; + } + + gen_pool_free(rwa_state.gen_pool, (unsigned long)area->buf, area->size); + mempool_free(area, &rwa_state.descriptor_pool); + wake_up(&rwa_state.wqh); +} + +/* + * Initialization of the work area allocator happens in two parts. To + * reliably reserve an arena that satisfies RTAS addressing + * requirements, we must perform a memblock allocation early, + * immmediately after RTAS instantiation. Then we have to wait until + * the slab allocator is up before setting up the descriptor mempool + * and adding the arena to a gen_pool. + */ +static __init int rtas_work_area_allocator_init(void) +{ + const unsigned int order = ilog2(RTAS_WORK_AREA_MIN_ALLOC_SZ); + const phys_addr_t pa_start = __pa(rwa_state.arena); + const phys_addr_t pa_end = pa_start + RTAS_WORK_AREA_ARENA_SZ - 1; + struct gen_pool *pool; + const int nid = NUMA_NO_NODE; + int err; + + err = -ENOMEM; + if (!rwa_state.arena) + goto err_out; + + pool = gen_pool_create(order, nid); + if (!pool) + goto err_out; + /* + * All RTAS functions that consume work areas are OK with + * natural alignment, when they have alignment requirements at + * all. + */ + gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL); + + err = gen_pool_add(pool, (unsigned long)rwa_state.arena, + RTAS_WORK_AREA_ARENA_SZ, nid); + if (err) + goto err_destroy; + + err = mempool_init_kmalloc_pool(&rwa_state.descriptor_pool, 1, + sizeof(struct rtas_work_area)); + if (err) + goto err_destroy; + + rwa_state.gen_pool = pool; + rwa_state.available = true; + + pr_debug("arena [%pa-%pa] (%uK), min/max alloc sizes %u/%u\n", + &pa_start, &pa_end, + RTAS_WORK_AREA_ARENA_SZ / SZ_1K, + RTAS_WORK_AREA_MIN_ALLOC_SZ, + RTAS_WORK_AREA_MAX_ALLOC_SZ); + + return 0; + +err_destroy: + gen_pool_destroy(pool); +err_out: + return err; +} +machine_arch_initcall(pseries, rtas_work_area_allocator_init); + +/** + * rtas_work_area_reserve_arena() - Reserve memory suitable for RTAS work areas. + * @limit: Upper limit for memblock allocation. + */ +void __init rtas_work_area_reserve_arena(const phys_addr_t limit) +{ + const phys_addr_t align = RTAS_WORK_AREA_ARENA_ALIGN; + const phys_addr_t size = RTAS_WORK_AREA_ARENA_SZ; + const phys_addr_t min = MEMBLOCK_LOW_LIMIT; + const int nid = NUMA_NO_NODE; + + /* + * Too early for a machine_is(pseries) check. But PAPR + * effectively mandates that ibm,get-system-parameter is + * present: + * + * R1–7.3.16–1. All platforms must support the System + * Parameters option. + * + * So set up the arena if we find that, with a fallback to + * ibm,configure-connector, just in case. + */ + if (rtas_function_implemented(RTAS_FN_IBM_GET_SYSTEM_PARAMETER) || + rtas_function_implemented(RTAS_FN_IBM_CONFIGURE_CONNECTOR)) + rwa_state.arena = memblock_alloc_try_nid(size, align, min, limit, nid); +} |