From: Bailey Forrest <bcf@google.com>
Date: Thu, 24 Jun 2021 11:06:26 -0700
Subject: gve: Add DQO fields for core data structures
Patch-mainline: v5.14-rc1
Git-commit: a4aa1f1e69df5612bcc0d7cf2ca23b9fae79941b
References: bsc#1176940
- Add new DQO datapath structures:
- `gve_rx_buf_queue_dqo`
- `gve_rx_compl_queue_dqo`
- `gve_rx_buf_state_dqo`
- `gve_tx_desc_dqo`
- `gve_tx_pending_packet_dqo`
- Incorporate these into the existing ring data structures:
- `gve_rx_ring`
- `gve_tx_ring`
Noteworthy mentions:
- `gve_rx_buf_state` represents an RX buffer which was posted to HW.
Each RX queue has an array of these objects and the index into the
array is used as the buffer_id when posted to HW.
- `gve_tx_pending_packet_dqo` is treated similarly for TX queues. The
completion_tag is the index into the array.
- These two structures have links for linked lists which are represented
by 16b indexes into a contiguous array of these structures.
This reduces memory footprint compared to 64b pointers.
- We use unions for the writeable datapath structures to reduce cache
footprint. GQI specific members will renamed like DQO members in a
future patch.
Signed-off-by: Bailey Forrest <bcf@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/net/ethernet/google/gve/gve.h | 262 ++++++++++++++++++++++++++++++++--
1 file changed, 251 insertions(+), 11 deletions(-)
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -13,6 +13,7 @@
#include <linux/u64_stats_sync.h>
#include "gve_desc.h"
+#include "gve_desc_dqo.h"
#ifndef PCI_VENDOR_ID_GOOGLE
#define PCI_VENDOR_ID_GOOGLE 0x1ae0
@@ -80,17 +81,117 @@ struct gve_rx_data_queue {
struct gve_priv;
-/* An RX ring that contains a power-of-two sized desc and data ring. */
+/* RX buffer queue for posting buffers to HW.
+ * Each RX (completion) queue has a corresponding buffer queue.
+ */
+struct gve_rx_buf_queue_dqo {
+ struct gve_rx_desc_dqo *desc_ring;
+ dma_addr_t bus;
+ u32 head; /* Pointer to start cleaning buffers at. */
+ u32 tail; /* Last posted buffer index + 1 */
+ u32 mask; /* Mask for indices to the size of the ring */
+};
+
+/* RX completion queue to receive packets from HW. */
+struct gve_rx_compl_queue_dqo {
+ struct gve_rx_compl_desc_dqo *desc_ring;
+ dma_addr_t bus;
+
+ /* Number of slots which did not have a buffer posted yet. We should not
+ * post more buffers than the queue size to avoid HW overrunning the
+ * queue.
+ */
+ int num_free_slots;
+
+ /* HW uses a "generation bit" to notify SW of new descriptors. When a
+ * descriptor's generation bit is different from the current generation,
+ * that descriptor is ready to be consumed by SW.
+ */
+ u8 cur_gen_bit;
+
+ /* Pointer into desc_ring where the next completion descriptor will be
+ * received.
+ */
+ u32 head;
+ u32 mask; /* Mask for indices to the size of the ring */
+};
+
+/* Stores state for tracking buffers posted to HW */
+struct gve_rx_buf_state_dqo {
+ /* The page posted to HW. */
+ struct gve_rx_slot_page_info page_info;
+
+ /* The DMA address corresponding to `page_info`. */
+ dma_addr_t addr;
+
+ /* Last offset into the page when it only had a single reference, at
+ * which point every other offset is free to be reused.
+ */
+ u32 last_single_ref_offset;
+
+ /* Linked list index to next element in the list, or -1 if none */
+ s16 next;
+};
+
+/* `head` and `tail` are indices into an array, or -1 if empty. */
+struct gve_index_list {
+ s16 head;
+ s16 tail;
+};
+
+/* Contains datapath state used to represent an RX queue. */
struct gve_rx_ring {
struct gve_priv *gve;
- struct gve_rx_desc_queue desc;
- struct gve_rx_data_queue data;
+ union {
+ /* GQI fields */
+ struct {
+ struct gve_rx_desc_queue desc;
+ struct gve_rx_data_queue data;
+
+ /* threshold for posting new buffs and descs */
+ u32 db_threshold;
+ };
+
+ /* DQO fields. */
+ struct {
+ struct gve_rx_buf_queue_dqo bufq;
+ struct gve_rx_compl_queue_dqo complq;
+
+ struct gve_rx_buf_state_dqo *buf_states;
+ u16 num_buf_states;
+
+ /* Linked list of gve_rx_buf_state_dqo. Index into
+ * buf_states, or -1 if empty.
+ */
+ s16 free_buf_states;
+
+ /* Linked list of gve_rx_buf_state_dqo. Indexes into
+ * buf_states, or -1 if empty.
+ *
+ * This list contains buf_states which are pointing to
+ * valid buffers.
+ *
+ * We use a FIFO here in order to increase the
+ * probability that buffers can be reused by increasing
+ * the time between usages.
+ */
+ struct gve_index_list recycled_buf_states;
+
+ /* Linked list of gve_rx_buf_state_dqo. Indexes into
+ * buf_states, or -1 if empty.
+ *
+ * This list contains buf_states which have buffers
+ * which cannot be reused yet.
+ */
+ struct gve_index_list used_buf_states;
+ } dqo;
+ };
+
u64 rbytes; /* free-running bytes received */
u64 rpackets; /* free-running packets received */
u32 cnt; /* free-running total number of completed packets */
u32 fill_cnt; /* free-running total number of descs and buffs posted */
u32 mask; /* masks the cnt and fill_cnt to the size of the ring */
- u32 db_threshold; /* threshold for posting new buffs and descs */
u64 rx_copybreak_pkt; /* free-running count of copybreak packets */
u64 rx_copied_pkt; /* free-running total number of copied packets */
u64 rx_skb_alloc_fail; /* free-running count of skb alloc fails */
@@ -141,23 +242,161 @@ struct gve_tx_fifo {
struct gve_queue_page_list *qpl; /* QPL mapped into this FIFO */
};
-/* A TX ring that contains a power-of-two sized desc ring and a FIFO buffer */
+/* TX descriptor for DQO format */
+union gve_tx_desc_dqo {
+ struct gve_tx_pkt_desc_dqo pkt;
+ struct gve_tx_tso_context_desc_dqo tso_ctx;
+ struct gve_tx_general_context_desc_dqo general_ctx;
+};
+
+enum gve_packet_state {
+ /* Packet is in free list, available to be allocated.
+ * This should always be zero since state is not explicitly initialized.
+ */
+ GVE_PACKET_STATE_UNALLOCATED,
+ /* Packet is expecting a regular data completion or miss completion */
+ GVE_PACKET_STATE_PENDING_DATA_COMPL,
+ /* Packet has received a miss completion and is expecting a
+ * re-injection completion.
+ */
+ GVE_PACKET_STATE_PENDING_REINJECT_COMPL,
+ /* No valid completion received within the specified timeout. */
+ GVE_PACKET_STATE_TIMED_OUT_COMPL,
+};
+
+struct gve_tx_pending_packet_dqo {
+ struct sk_buff *skb; /* skb for this packet */
+
+ /* 0th element corresponds to the linear portion of `skb`, should be
+ * unmapped with `dma_unmap_single`.
+ *
+ * All others correspond to `skb`'s frags and should be unmapped with
+ * `dma_unmap_page`.
+ */
+ struct gve_tx_dma_buf bufs[MAX_SKB_FRAGS + 1];
+ u16 num_bufs;
+
+ /* Linked list index to next element in the list, or -1 if none */
+ s16 next;
+
+ /* Linked list index to prev element in the list, or -1 if none.
+ * Used for tracking either outstanding miss completions or prematurely
+ * freed packets.
+ */
+ s16 prev;
+
+ /* Identifies the current state of the packet as defined in
+ * `enum gve_packet_state`.
+ */
+ u8 state;
+
+ /* If packet is an outstanding miss completion, then the packet is
+ * freed if the corresponding re-injection completion is not received
+ * before kernel jiffies exceeds timeout_jiffies.
+ */
+ unsigned long timeout_jiffies;
+};
+
+/* Contains datapath state used to represent a TX queue. */
struct gve_tx_ring {
/* Cacheline 0 -- Accessed & dirtied during transmit */
- struct gve_tx_fifo tx_fifo;
- u32 req; /* driver tracked head pointer */
- u32 done; /* driver tracked tail pointer */
+ union {
+ /* GQI fields */
+ struct {
+ struct gve_tx_fifo tx_fifo;
+ u32 req; /* driver tracked head pointer */
+ u32 done; /* driver tracked tail pointer */
+ };
+
+ /* DQO fields. */
+ struct {
+ /* Linked list of gve_tx_pending_packet_dqo. Index into
+ * pending_packets, or -1 if empty.
+ *
+ * This is a consumer list owned by the TX path. When it
+ * runs out, the producer list is stolen from the
+ * completion handling path
+ * (dqo_compl.free_pending_packets).
+ */
+ s16 free_pending_packets;
+
+ /* Cached value of `dqo_compl.hw_tx_head` */
+ u32 head;
+ u32 tail; /* Last posted buffer index + 1 */
+
+ /* Index of the last descriptor with "report event" bit
+ * set.
+ */
+ u32 last_re_idx;
+ } dqo_tx;
+ };
/* Cacheline 1 -- Accessed & dirtied during gve_clean_tx_done */
- __be32 last_nic_done ____cacheline_aligned; /* NIC tail pointer */
+ union {
+ /* GQI fields */
+ struct {
+ /* NIC tail pointer */
+ __be32 last_nic_done;
+ };
+
+ /* DQO fields. */
+ struct {
+ u32 head; /* Last read on compl_desc */
+
+ /* Tracks the current gen bit of compl_q */
+ u8 cur_gen_bit;
+
+ /* Linked list of gve_tx_pending_packet_dqo. Index into
+ * pending_packets, or -1 if empty.
+ *
+ * This is the producer list, owned by the completion
+ * handling path. When the consumer list
+ * (dqo_tx.free_pending_packets) is runs out, this list
+ * will be stolen.
+ */
+ atomic_t free_pending_packets;
+
+ /* Last TX ring index fetched by HW */
+ atomic_t hw_tx_head;
+
+ /* List to track pending packets which received a miss
+ * completion but not a corresponding reinjection.
+ */
+ struct gve_index_list miss_completions;
+
+ /* List to track pending packets that were completed
+ * before receiving a valid completion because they
+ * reached a specified timeout.
+ */
+ struct gve_index_list timed_out_completions;
+ } dqo_compl;
+ } ____cacheline_aligned;
u64 pkt_done; /* free-running - total packets completed */
u64 bytes_done; /* free-running - total bytes completed */
u64 dropped_pkt; /* free-running - total packets dropped */
u64 dma_mapping_error; /* count of dma mapping errors */
/* Cacheline 2 -- Read-mostly fields */
- union gve_tx_desc *desc ____cacheline_aligned;
- struct gve_tx_buffer_state *info; /* Maps 1:1 to a desc */
+ union {
+ /* GQI fields */
+ struct {
+ union gve_tx_desc *desc;
+
+ /* Maps 1:1 to a desc */
+ struct gve_tx_buffer_state *info;
+ };
+
+ /* DQO fields. */
+ struct {
+ union gve_tx_desc_dqo *tx_ring;
+ struct gve_tx_compl_desc *compl_ring;
+
+ struct gve_tx_pending_packet_dqo *pending_packets;
+ s16 num_pending_packets;
+
+ u32 complq_mask; /* complq size is complq_mask + 1 */
+ } dqo;
+ } ____cacheline_aligned;
struct netdev_queue *netdev_txq;
struct gve_queue_resources *q_resources; /* head and tail pointer idx */
struct device *dev;
@@ -171,6 +410,7 @@ struct gve_tx_ring {
u32 ntfy_id; /* notification block index */
dma_addr_t bus; /* dma address of the descr ring */
dma_addr_t q_resources_bus; /* dma address of the queue resources */
+ dma_addr_t complq_bus_dqo; /* dma address of the dqo.compl_ring */
struct u64_stats_sync statss; /* sync stats for 32bit archs */
} ____cacheline_aligned;