linux/net/core/xdp.c
Björn Töpel 02b55e5657 xdp: add MEM_TYPE_ZERO_COPY
Here, a new type of allocator support is added to the XDP return
API. A zero-copy allocated xdp_buff cannot be converted to an
xdp_frame. Instead is the buff has to be copied. This is not supported
at all in this commit.

Also, an opaque "handle" is added to xdp_buff. This can be used as a
context for the zero-copy allocator implementation.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-06-05 15:46:26 +02:00

373 lines
8.5 KiB
C

/* net/core/xdp.c
*
* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
* Released under terms in GPL version 2. See COPYING.
*/
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/rhashtable.h>
#include <net/page_pool.h>
#include <net/xdp.h>
#define REG_STATE_NEW 0x0
#define REG_STATE_REGISTERED 0x1
#define REG_STATE_UNREGISTERED 0x2
#define REG_STATE_UNUSED 0x3
static DEFINE_IDA(mem_id_pool);
static DEFINE_MUTEX(mem_id_lock);
#define MEM_ID_MAX 0xFFFE
#define MEM_ID_MIN 1
static int mem_id_next = MEM_ID_MIN;
static bool mem_id_init; /* false */
static struct rhashtable *mem_id_ht;
struct xdp_mem_allocator {
struct xdp_mem_info mem;
union {
void *allocator;
struct page_pool *page_pool;
struct zero_copy_allocator *zc_alloc;
};
struct rhash_head node;
struct rcu_head rcu;
};
static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
{
const u32 *k = data;
const u32 key = *k;
BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_mem_allocator, mem.id)
!= sizeof(u32));
/* Use cyclic increasing ID as direct hash key, see rht_bucket_index */
return key << RHT_HASH_RESERVED_SPACE;
}
static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
const struct xdp_mem_allocator *xa = ptr;
u32 mem_id = *(u32 *)arg->key;
return xa->mem.id != mem_id;
}
static const struct rhashtable_params mem_id_rht_params = {
.nelem_hint = 64,
.head_offset = offsetof(struct xdp_mem_allocator, node),
.key_offset = offsetof(struct xdp_mem_allocator, mem.id),
.key_len = FIELD_SIZEOF(struct xdp_mem_allocator, mem.id),
.max_size = MEM_ID_MAX,
.min_size = 8,
.automatic_shrinking = true,
.hashfn = xdp_mem_id_hashfn,
.obj_cmpfn = xdp_mem_id_cmp,
};
static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
{
struct xdp_mem_allocator *xa;
xa = container_of(rcu, struct xdp_mem_allocator, rcu);
/* Allow this ID to be reused */
ida_simple_remove(&mem_id_pool, xa->mem.id);
/* Notice, driver is expected to free the *allocator,
* e.g. page_pool, and MUST also use RCU free.
*/
/* Poison memory */
xa->mem.id = 0xFFFF;
xa->mem.type = 0xF0F0;
xa->allocator = (void *)0xDEAD9001;
kfree(xa);
}
static void __xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
{
struct xdp_mem_allocator *xa;
int id = xdp_rxq->mem.id;
int err;
if (id == 0)
return;
mutex_lock(&mem_id_lock);
xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
if (!xa) {
mutex_unlock(&mem_id_lock);
return;
}
err = rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params);
WARN_ON(err);
call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
mutex_unlock(&mem_id_lock);
}
void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
{
/* Simplify driver cleanup code paths, allow unreg "unused" */
if (xdp_rxq->reg_state == REG_STATE_UNUSED)
return;
WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");
__xdp_rxq_info_unreg_mem_model(xdp_rxq);
xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
xdp_rxq->dev = NULL;
/* Reset mem info to defaults */
xdp_rxq->mem.id = 0;
xdp_rxq->mem.type = 0;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
{
memset(xdp_rxq, 0, sizeof(*xdp_rxq));
}
/* Returns 0 on success, negative on failure */
int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
struct net_device *dev, u32 queue_index)
{
if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
WARN(1, "Driver promised not to register this");
return -EINVAL;
}
if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
WARN(1, "Missing unregister, handled but fix driver");
xdp_rxq_info_unreg(xdp_rxq);
}
if (!dev) {
WARN(1, "Missing net_device from driver");
return -ENODEV;
}
/* State either UNREGISTERED or NEW */
xdp_rxq_info_init(xdp_rxq);
xdp_rxq->dev = dev;
xdp_rxq->queue_index = queue_index;
xdp_rxq->reg_state = REG_STATE_REGISTERED;
return 0;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
{
xdp_rxq->reg_state = REG_STATE_UNUSED;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
{
return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
static int __mem_id_init_hash_table(void)
{
struct rhashtable *rht;
int ret;
if (unlikely(mem_id_init))
return 0;
rht = kzalloc(sizeof(*rht), GFP_KERNEL);
if (!rht)
return -ENOMEM;
ret = rhashtable_init(rht, &mem_id_rht_params);
if (ret < 0) {
kfree(rht);
return ret;
}
mem_id_ht = rht;
smp_mb(); /* mutex lock should provide enough pairing */
mem_id_init = true;
return 0;
}
/* Allocate a cyclic ID that maps to allocator pointer.
* See: https://www.kernel.org/doc/html/latest/core-api/idr.html
*
* Caller must lock mem_id_lock.
*/
static int __mem_id_cyclic_get(gfp_t gfp)
{
int retries = 1;
int id;
again:
id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
if (id < 0) {
if (id == -ENOSPC) {
/* Cyclic allocator, reset next id */
if (retries--) {
mem_id_next = MEM_ID_MIN;
goto again;
}
}
return id; /* errno */
}
mem_id_next = id + 1;
return id;
}
static bool __is_supported_mem_type(enum xdp_mem_type type)
{
if (type == MEM_TYPE_PAGE_POOL)
return is_page_pool_compiled_in();
if (type >= MEM_TYPE_MAX)
return false;
return true;
}
int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
enum xdp_mem_type type, void *allocator)
{
struct xdp_mem_allocator *xdp_alloc;
gfp_t gfp = GFP_KERNEL;
int id, errno, ret;
void *ptr;
if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
WARN(1, "Missing register, driver bug");
return -EFAULT;
}
if (!__is_supported_mem_type(type))
return -EOPNOTSUPP;
xdp_rxq->mem.type = type;
if (!allocator) {
if (type == MEM_TYPE_PAGE_POOL || type == MEM_TYPE_ZERO_COPY)
return -EINVAL; /* Setup time check page_pool req */
return 0;
}
/* Delay init of rhashtable to save memory if feature isn't used */
if (!mem_id_init) {
mutex_lock(&mem_id_lock);
ret = __mem_id_init_hash_table();
mutex_unlock(&mem_id_lock);
if (ret < 0) {
WARN_ON(1);
return ret;
}
}
xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
if (!xdp_alloc)
return -ENOMEM;
mutex_lock(&mem_id_lock);
id = __mem_id_cyclic_get(gfp);
if (id < 0) {
errno = id;
goto err;
}
xdp_rxq->mem.id = id;
xdp_alloc->mem = xdp_rxq->mem;
xdp_alloc->allocator = allocator;
/* Insert allocator into ID lookup table */
ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
if (IS_ERR(ptr)) {
errno = PTR_ERR(ptr);
goto err;
}
mutex_unlock(&mem_id_lock);
return 0;
err:
mutex_unlock(&mem_id_lock);
kfree(xdp_alloc);
return errno;
}
EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
/* XDP RX runs under NAPI protection, and in different delivery error
* scenarios (e.g. queue full), it is possible to return the xdp_frame
* while still leveraging this protection. The @napi_direct boolian
* is used for those calls sites. Thus, allowing for faster recycling
* of xdp_frames/pages in those cases.
*/
static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
unsigned long handle)
{
struct xdp_mem_allocator *xa;
struct page *page;
switch (mem->type) {
case MEM_TYPE_PAGE_POOL:
rcu_read_lock();
/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
page = virt_to_head_page(data);
if (xa)
page_pool_put_page(xa->page_pool, page, napi_direct);
else
put_page(page);
rcu_read_unlock();
break;
case MEM_TYPE_PAGE_SHARED:
page_frag_free(data);
break;
case MEM_TYPE_PAGE_ORDER0:
page = virt_to_page(data); /* Assumes order0 page*/
put_page(page);
break;
case MEM_TYPE_ZERO_COPY:
/* NB! Only valid from an xdp_buff! */
rcu_read_lock();
/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
xa->zc_alloc->free(xa->zc_alloc, handle);
rcu_read_unlock();
default:
/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
break;
}
}
void xdp_return_frame(struct xdp_frame *xdpf)
{
__xdp_return(xdpf->data, &xdpf->mem, false, 0);
}
EXPORT_SYMBOL_GPL(xdp_return_frame);
void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
{
__xdp_return(xdpf->data, &xdpf->mem, true, 0);
}
EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
void xdp_return_buff(struct xdp_buff *xdp)
{
__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp->handle);
}
EXPORT_SYMBOL_GPL(xdp_return_buff);