diff options
author | Bert Kenward <bkenward@solarflare.com> | 2016-11-17 10:51:54 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-11-18 11:55:38 -0500 |
commit | e9117e5099ea29592c2a6180f368951948837a8b (patch) | |
tree | 865d0862309b88b06a249b3cc949aee1589ba7ef /drivers/net/ethernet/sfc/tx_tso.c | |
parent | e17705c43b4273d2587297d5f8168ee432d9c94a (diff) | |
download | linux-e9117e5099ea29592c2a6180f368951948837a8b.tar.bz2 |
sfc: Firmware-Assisted TSO version 2
Add support for FATSOv2 to the driver. FATSOv2 offloads far more of the task
of TCP segmentation to the firmware, such that we now just pass a single
super-packet to the NIC. This means TSO has a great deal in common with a
normal DMA transmit, apart from adding a couple of option descriptors.
NIC-specific checks have been moved off the fast path and in to
initialisation where possible.
This also moves FATSOv1/SWTSO to a new file (tx_tso.c). The end of transmit
and some error handling is now outside TSO, since it is common with other
code.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/sfc/tx_tso.c')
-rw-r--r-- | drivers/net/ethernet/sfc/tx_tso.c | 570 |
1 files changed, 570 insertions, 0 deletions
diff --git a/drivers/net/ethernet/sfc/tx_tso.c b/drivers/net/ethernet/sfc/tx_tso.c new file mode 100644 index 000000000000..99936d70ed71 --- /dev/null +++ b/drivers/net/ethernet/sfc/tx_tso.c @@ -0,0 +1,570 @@ +/**************************************************************************** + * Driver for Solarflare network controllers and boards + * Copyright 2005-2006 Fen Systems Ltd. + * Copyright 2005-2015 Solarflare Communications Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation, incorporated herein by reference. + */ + +#include <linux/pci.h> +#include <linux/tcp.h> +#include <linux/ip.h> +#include <linux/in.h> +#include <linux/ipv6.h> +#include <linux/slab.h> +#include <net/ipv6.h> +#include <linux/if_ether.h> +#include <linux/highmem.h> +#include <linux/moduleparam.h> +#include <linux/cache.h> +#include "net_driver.h" +#include "efx.h" +#include "io.h" +#include "nic.h" +#include "tx.h" +#include "workarounds.h" +#include "ef10_regs.h" + +/* Efx legacy TCP segmentation acceleration. + * + * Why? Because by doing it here in the driver we can go significantly + * faster than the GSO. + * + * Requires TX checksum offload support. + */ + +#define PTR_DIFF(p1, p2) ((u8 *)(p1) - (u8 *)(p2)) + +/** + * struct tso_state - TSO state for an SKB + * @out_len: Remaining length in current segment + * @seqnum: Current sequence number + * @ipv4_id: Current IPv4 ID, host endian + * @packet_space: Remaining space in current packet + * @dma_addr: DMA address of current position + * @in_len: Remaining length in current SKB fragment + * @unmap_len: Length of SKB fragment + * @unmap_addr: DMA address of SKB fragment + * @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0 + * @protocol: Network protocol (after any VLAN header) + * @ip_off: Offset of IP header + * @tcp_off: Offset of TCP header + * @header_len: Number of bytes of header + * @ip_base_len: IPv4 tot_len or IPv6 payload_len, before TCP payload + * @header_dma_addr: Header DMA address, when using option descriptors + * @header_unmap_len: Header DMA mapped length, or 0 if not using option + * descriptors + * + * The state used during segmentation. It is put into this data structure + * just to make it easy to pass into inline functions. + */ +struct tso_state { + /* Output position */ + unsigned int out_len; + unsigned int seqnum; + u16 ipv4_id; + unsigned int packet_space; + + /* Input position */ + dma_addr_t dma_addr; + unsigned int in_len; + unsigned int unmap_len; + dma_addr_t unmap_addr; + unsigned short dma_flags; + + __be16 protocol; + unsigned int ip_off; + unsigned int tcp_off; + unsigned int header_len; + unsigned int ip_base_len; + dma_addr_t header_dma_addr; + unsigned int header_unmap_len; +}; + +static inline void prefetch_ptr(struct efx_tx_queue *tx_queue) +{ + unsigned int insert_ptr = efx_tx_queue_get_insert_index(tx_queue); + char *ptr; + + ptr = (char *) (tx_queue->buffer + insert_ptr); + prefetch(ptr); + prefetch(ptr + 0x80); + + ptr = (char *) (((efx_qword_t *)tx_queue->txd.buf.addr) + insert_ptr); + prefetch(ptr); + prefetch(ptr + 0x80); +} + +/** + * efx_tx_queue_insert - push descriptors onto the TX queue + * @tx_queue: Efx TX queue + * @dma_addr: DMA address of fragment + * @len: Length of fragment + * @final_buffer: The final buffer inserted into the queue + * + * Push descriptors onto the TX queue. + */ +static void efx_tx_queue_insert(struct efx_tx_queue *tx_queue, + dma_addr_t dma_addr, unsigned int len, + struct efx_tx_buffer **final_buffer) +{ + struct efx_tx_buffer *buffer; + unsigned int dma_len; + + EFX_BUG_ON_PARANOID(len <= 0); + + while (1) { + buffer = efx_tx_queue_get_insert_buffer(tx_queue); + ++tx_queue->insert_count; + + EFX_BUG_ON_PARANOID(tx_queue->insert_count - + tx_queue->read_count >= + tx_queue->efx->txq_entries); + + buffer->dma_addr = dma_addr; + + dma_len = tx_queue->efx->type->tx_limit_len(tx_queue, + dma_addr, len); + + /* If there's space for everything this is our last buffer. */ + if (dma_len >= len) + break; + + buffer->len = dma_len; + buffer->flags = EFX_TX_BUF_CONT; + dma_addr += dma_len; + len -= dma_len; + } + + EFX_BUG_ON_PARANOID(!len); + buffer->len = len; + *final_buffer = buffer; +} + +/* + * Verify that our various assumptions about sk_buffs and the conditions + * under which TSO will be attempted hold true. Return the protocol number. + */ +static __be16 efx_tso_check_protocol(struct sk_buff *skb) +{ + __be16 protocol = skb->protocol; + + EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto != + protocol); + if (protocol == htons(ETH_P_8021Q)) { + struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data; + + protocol = veh->h_vlan_encapsulated_proto; + } + + if (protocol == htons(ETH_P_IP)) { + EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP); + } else { + EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IPV6)); + EFX_BUG_ON_PARANOID(ipv6_hdr(skb)->nexthdr != NEXTHDR_TCP); + } + EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data) + + (tcp_hdr(skb)->doff << 2u)) > + skb_headlen(skb)); + + return protocol; +} + +static u8 *efx_tsoh_get_buffer(struct efx_tx_queue *tx_queue, + struct efx_tx_buffer *buffer, unsigned int len) +{ + u8 *result; + + EFX_BUG_ON_PARANOID(buffer->len); + EFX_BUG_ON_PARANOID(buffer->flags); + EFX_BUG_ON_PARANOID(buffer->unmap_len); + + result = efx_tx_get_copy_buffer_limited(tx_queue, buffer, len); + + if (result) { + buffer->flags = EFX_TX_BUF_CONT; + } else { + buffer->heap_buf = kmalloc(NET_IP_ALIGN + len, GFP_ATOMIC); + if (unlikely(!buffer->heap_buf)) + return NULL; + tx_queue->tso_long_headers++; + result = (u8 *)buffer->heap_buf + NET_IP_ALIGN; + buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_HEAP; + } + + buffer->len = len; + + return result; +} + +/* + * Put a TSO header into the TX queue. + * + * This is special-cased because we know that it is small enough to fit in + * a single fragment, and we know it doesn't cross a page boundary. It + * also allows us to not worry about end-of-packet etc. + */ +static int efx_tso_put_header(struct efx_tx_queue *tx_queue, + struct efx_tx_buffer *buffer, u8 *header) +{ + if (unlikely(buffer->flags & EFX_TX_BUF_HEAP)) { + buffer->dma_addr = dma_map_single(&tx_queue->efx->pci_dev->dev, + header, buffer->len, + DMA_TO_DEVICE); + if (unlikely(dma_mapping_error(&tx_queue->efx->pci_dev->dev, + buffer->dma_addr))) { + kfree(buffer->heap_buf); + buffer->len = 0; + buffer->flags = 0; + return -ENOMEM; + } + buffer->unmap_len = buffer->len; + buffer->dma_offset = 0; + buffer->flags |= EFX_TX_BUF_MAP_SINGLE; + } + + ++tx_queue->insert_count; + return 0; +} + + +/* Parse the SKB header and initialise state. */ +static int tso_start(struct tso_state *st, struct efx_nic *efx, + struct efx_tx_queue *tx_queue, + const struct sk_buff *skb) +{ + struct device *dma_dev = &efx->pci_dev->dev; + unsigned int header_len, in_len; + bool use_opt_desc = false; + dma_addr_t dma_addr; + + if (tx_queue->tso_version == 1) + use_opt_desc = true; + + st->ip_off = skb_network_header(skb) - skb->data; + st->tcp_off = skb_transport_header(skb) - skb->data; + header_len = st->tcp_off + (tcp_hdr(skb)->doff << 2u); + in_len = skb_headlen(skb) - header_len; + st->header_len = header_len; + st->in_len = in_len; + if (st->protocol == htons(ETH_P_IP)) { + st->ip_base_len = st->header_len - st->ip_off; + st->ipv4_id = ntohs(ip_hdr(skb)->id); + } else { + st->ip_base_len = st->header_len - st->tcp_off; + st->ipv4_id = 0; + } + st->seqnum = ntohl(tcp_hdr(skb)->seq); + + EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg); + EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn); + EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst); + + st->out_len = skb->len - header_len; + + if (!use_opt_desc) { + st->header_unmap_len = 0; + + if (likely(in_len == 0)) { + st->dma_flags = 0; + st->unmap_len = 0; + return 0; + } + + dma_addr = dma_map_single(dma_dev, skb->data + header_len, + in_len, DMA_TO_DEVICE); + st->dma_flags = EFX_TX_BUF_MAP_SINGLE; + st->dma_addr = dma_addr; + st->unmap_addr = dma_addr; + st->unmap_len = in_len; + } else { + dma_addr = dma_map_single(dma_dev, skb->data, + skb_headlen(skb), DMA_TO_DEVICE); + st->header_dma_addr = dma_addr; + st->header_unmap_len = skb_headlen(skb); + st->dma_flags = 0; + st->dma_addr = dma_addr + header_len; + st->unmap_len = 0; + } + + return unlikely(dma_mapping_error(dma_dev, dma_addr)) ? -ENOMEM : 0; +} + +static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx, + skb_frag_t *frag) +{ + st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0, + skb_frag_size(frag), DMA_TO_DEVICE); + if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) { + st->dma_flags = 0; + st->unmap_len = skb_frag_size(frag); + st->in_len = skb_frag_size(frag); + st->dma_addr = st->unmap_addr; + return 0; + } + return -ENOMEM; +} + + +/** + * tso_fill_packet_with_fragment - form descriptors for the current fragment + * @tx_queue: Efx TX queue + * @skb: Socket buffer + * @st: TSO state + * + * Form descriptors for the current fragment, until we reach the end + * of fragment or end-of-packet. + */ +static void tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue, + const struct sk_buff *skb, + struct tso_state *st) +{ + struct efx_tx_buffer *buffer; + int n; + + if (st->in_len == 0) + return; + if (st->packet_space == 0) + return; + + EFX_BUG_ON_PARANOID(st->in_len <= 0); + EFX_BUG_ON_PARANOID(st->packet_space <= 0); + + n = min(st->in_len, st->packet_space); + + st->packet_space -= n; + st->out_len -= n; + st->in_len -= n; + + efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer); + + if (st->out_len == 0) { + /* Transfer ownership of the skb */ + buffer->skb = skb; + buffer->flags = EFX_TX_BUF_SKB; + } else if (st->packet_space != 0) { + buffer->flags = EFX_TX_BUF_CONT; + } + + if (st->in_len == 0) { + /* Transfer ownership of the DMA mapping */ + buffer->unmap_len = st->unmap_len; + buffer->dma_offset = buffer->unmap_len - buffer->len; + buffer->flags |= st->dma_flags; + st->unmap_len = 0; + } + + st->dma_addr += n; +} + + +#define TCP_FLAGS_OFFSET 13 + +/** + * tso_start_new_packet - generate a new header and prepare for the new packet + * @tx_queue: Efx TX queue + * @skb: Socket buffer + * @st: TSO state + * + * Generate a new header and prepare for the new packet. Return 0 on + * success, or -%ENOMEM if failed to alloc header. + */ +static int tso_start_new_packet(struct efx_tx_queue *tx_queue, + const struct sk_buff *skb, + struct tso_state *st) +{ + struct efx_tx_buffer *buffer = + efx_tx_queue_get_insert_buffer(tx_queue); + bool is_last = st->out_len <= skb_shinfo(skb)->gso_size; + u8 tcp_flags_mask; + + if (!is_last) { + st->packet_space = skb_shinfo(skb)->gso_size; + tcp_flags_mask = 0x09; /* mask out FIN and PSH */ + } else { + st->packet_space = st->out_len; + tcp_flags_mask = 0x00; + } + + if (!st->header_unmap_len) { + /* Allocate and insert a DMA-mapped header buffer. */ + struct tcphdr *tsoh_th; + unsigned int ip_length; + u8 *header; + int rc; + + header = efx_tsoh_get_buffer(tx_queue, buffer, st->header_len); + if (!header) + return -ENOMEM; + + tsoh_th = (struct tcphdr *)(header + st->tcp_off); + + /* Copy and update the headers. */ + memcpy(header, skb->data, st->header_len); + + tsoh_th->seq = htonl(st->seqnum); + ((u8 *)tsoh_th)[TCP_FLAGS_OFFSET] &= ~tcp_flags_mask; + + ip_length = st->ip_base_len + st->packet_space; + + if (st->protocol == htons(ETH_P_IP)) { + struct iphdr *tsoh_iph = + (struct iphdr *)(header + st->ip_off); + + tsoh_iph->tot_len = htons(ip_length); + tsoh_iph->id = htons(st->ipv4_id); + } else { + struct ipv6hdr *tsoh_iph = + (struct ipv6hdr *)(header + st->ip_off); + + tsoh_iph->payload_len = htons(ip_length); + } + + rc = efx_tso_put_header(tx_queue, buffer, header); + if (unlikely(rc)) + return rc; + } else { + /* Send the original headers with a TSO option descriptor + * in front + */ + u8 tcp_flags = ((u8 *)tcp_hdr(skb))[TCP_FLAGS_OFFSET] & + ~tcp_flags_mask; + + buffer->flags = EFX_TX_BUF_OPTION; + buffer->len = 0; + buffer->unmap_len = 0; + EFX_POPULATE_QWORD_5(buffer->option, + ESF_DZ_TX_DESC_IS_OPT, 1, + ESF_DZ_TX_OPTION_TYPE, + ESE_DZ_TX_OPTION_DESC_TSO, + ESF_DZ_TX_TSO_TCP_FLAGS, tcp_flags, + ESF_DZ_TX_TSO_IP_ID, st->ipv4_id, + ESF_DZ_TX_TSO_TCP_SEQNO, st->seqnum); + ++tx_queue->insert_count; + + /* We mapped the headers in tso_start(). Unmap them + * when the last segment is completed. + */ + buffer = efx_tx_queue_get_insert_buffer(tx_queue); + buffer->dma_addr = st->header_dma_addr; + buffer->len = st->header_len; + if (is_last) { + buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_MAP_SINGLE; + buffer->unmap_len = st->header_unmap_len; + buffer->dma_offset = 0; + /* Ensure we only unmap them once in case of a + * later DMA mapping error and rollback + */ + st->header_unmap_len = 0; + } else { + buffer->flags = EFX_TX_BUF_CONT; + buffer->unmap_len = 0; + } + ++tx_queue->insert_count; + } + + st->seqnum += skb_shinfo(skb)->gso_size; + + /* Linux leaves suitable gaps in the IP ID space for us to fill. */ + ++st->ipv4_id; + + return 0; +} + +/** + * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer + * @tx_queue: Efx TX queue + * @skb: Socket buffer + * @data_mapped: Did we map the data? Always set to true + * by this on success. + * + * Context: You must hold netif_tx_lock() to call this function. + * + * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if + * @skb was not enqueued. In all cases @skb is consumed. Return + * %NETDEV_TX_OK. + */ +int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, + struct sk_buff *skb, + bool *data_mapped) +{ + struct efx_nic *efx = tx_queue->efx; + int frag_i, rc; + struct tso_state state; + + prefetch(skb->data); + + /* Find the packet protocol and sanity-check it */ + state.protocol = efx_tso_check_protocol(skb); + + EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count); + + rc = tso_start(&state, efx, tx_queue, skb); + if (rc) + goto mem_err; + + if (likely(state.in_len == 0)) { + /* Grab the first payload fragment. */ + EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1); + frag_i = 0; + rc = tso_get_fragment(&state, efx, + skb_shinfo(skb)->frags + frag_i); + if (rc) + goto mem_err; + } else { + /* Payload starts in the header area. */ + frag_i = -1; + } + + if (tso_start_new_packet(tx_queue, skb, &state) < 0) + goto mem_err; + + prefetch_ptr(tx_queue); + + while (1) { + tso_fill_packet_with_fragment(tx_queue, skb, &state); + + /* Move onto the next fragment? */ + if (state.in_len == 0) { + if (++frag_i >= skb_shinfo(skb)->nr_frags) + /* End of payload reached. */ + break; + rc = tso_get_fragment(&state, efx, + skb_shinfo(skb)->frags + frag_i); + if (rc) + goto mem_err; + } + + /* Start at new packet? */ + if (state.packet_space == 0 && + tso_start_new_packet(tx_queue, skb, &state) < 0) + goto mem_err; + } + + *data_mapped = true; + + return 0; + + mem_err: + netif_err(efx, tx_err, efx->net_dev, + "Out of memory for TSO headers, or DMA mapping error\n"); + + /* Free the DMA mapping we were in the process of writing out */ + if (state.unmap_len) { + if (state.dma_flags & EFX_TX_BUF_MAP_SINGLE) + dma_unmap_single(&efx->pci_dev->dev, state.unmap_addr, + state.unmap_len, DMA_TO_DEVICE); + else + dma_unmap_page(&efx->pci_dev->dev, state.unmap_addr, + state.unmap_len, DMA_TO_DEVICE); + } + + /* Free the header DMA mapping, if using option descriptors */ + if (state.header_unmap_len) + dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr, + state.header_unmap_len, DMA_TO_DEVICE); + + return -ENOMEM; +} |