gve: Add transmit and receive support

Add support for passing traffic.

Signed-off-by: Catherine Sullivan <csully@google.com>
Signed-off-by: Sagi Shahar <sagis@google.com>
Signed-off-by: Jon Olson <jonolson@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Luigi Rizzo <lrizzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/device_drivers/google/gve.rst

@@ -42,6 +42,8 @@ The driver interacts with the device in the following ways:
     - See description below
  - Interrupts
     - See supported interrupts below
+ - Transmit and Receive Queues
+    - See description below
 
 Registers
 ---------
@@ -80,3 +82,31 @@ Notification Block Interrupts
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The notification block interrupts are used to tell the driver to poll
 the queues associated with that interrupt.
+
+The handler for these irqs schedule the napi for that block to run
+and poll the queues.
+
+Traffic Queues
+--------------
+gVNIC's queues are composed of a descriptor ring and a buffer and are
+assigned to a notification block.
+
+The descriptor rings are power-of-two-sized ring buffers consisting of
+fixed-size descriptors. They advance their head pointer using a __be32
+doorbell located in Bar2. The tail pointers are advanced by consuming
+descriptors in-order and updating a __be32 counter. Both the doorbell
+and the counter overflow to zero.
+
+Each queue's buffers must be registered in advance with the device as a
+queue page list, and packet data can only be put in those pages.
+
+Transmit
+~~~~~~~~
+gve maps the buffers for transmit rings into a FIFO and copies the packets
+into the FIFO before sending them to the NIC.
+
+Receive
+~~~~~~~
+The buffers for receive rings are put into a data ring that is the same
+length as the descriptor ring and the head and tail pointers advance over
+the rings together.

drivers/net/ethernet/google/gve/Makefile

@@ -1,4 +1,4 @@
 # Makefile for the Google virtual Ethernet (gve) driver
 
 obj-$(CONFIG_GVE) += gve.o
-gve-objs := gve_main.o gve_adminq.o
+gve-objs := gve_main.o gve_tx.o gve_rx.o gve_adminq.o

drivers/net/ethernet/google/gve/gve.h

@@ -10,6 +10,8 @@
 #include <linux/dma-mapping.h>
 #include <linux/netdevice.h>
 #include <linux/pci.h>
+#include <linux/u64_stats_sync.h>
+#include "gve_desc.h"
 
 #ifndef PCI_VENDOR_ID_GOOGLE
 #define PCI_VENDOR_ID_GOOGLE	0x1ae0
@@ -20,18 +22,152 @@
 #define GVE_REGISTER_BAR	0
 #define GVE_DOORBELL_BAR	2
 
-/* 1 for management */
+/* Driver can alloc up to 2 segments for the header and 2 for the payload. */
+#define GVE_TX_MAX_IOVEC	4
+/* 1 for management, 1 for rx, 1 for tx */
 #define GVE_MIN_MSIX 3
 
+/* Each slot in the desc ring has a 1:1 mapping to a slot in the data ring */
+struct gve_rx_desc_queue {
+	struct gve_rx_desc *desc_ring; /* the descriptor ring */
+	dma_addr_t bus; /* the bus for the desc_ring */
+	u32 cnt; /* free-running total number of completed packets */
+	u32 fill_cnt; /* free-running total number of descriptors posted */
+	u32 mask; /* masks the cnt to the size of the ring */
+	u8 seqno; /* the next expected seqno for this desc*/
+};
+
+/* The page info for a single slot in the RX data queue */
+struct gve_rx_slot_page_info {
+	struct page *page;
+	void *page_address;
+	u32 page_offset; /* offset to write to in page */
+};
+
+/* A list of pages registered with the device during setup and used by a queue
+ * as buffers
+ */
+struct gve_queue_page_list {
+	u32 id; /* unique id */
+	u32 num_entries;
+	struct page **pages; /* list of num_entries pages */
+	dma_addr_t *page_buses; /* the dma addrs of the pages */
+};
+
+/* Each slot in the data ring has a 1:1 mapping to a slot in the desc ring */
+struct gve_rx_data_queue {
+	struct gve_rx_data_slot *data_ring; /* read by NIC */
+	dma_addr_t data_bus; /* dma mapping of the slots */
+	struct gve_rx_slot_page_info *page_info; /* page info of the buffers */
+	struct gve_queue_page_list *qpl; /* qpl assigned to this queue */
+	u32 mask; /* masks the cnt to the size of the ring */
+	u32 cnt; /* free-running total number of completed packets */
+};
+
+struct gve_priv;
+
+/* An RX ring that contains a power-of-two sized desc and data ring. */
+struct gve_rx_ring {
+	struct gve_priv *gve;
+	struct gve_rx_desc_queue desc;
+	struct gve_rx_data_queue data;
+	u64 rbytes; /* free-running bytes received */
+	u64 rpackets; /* free-running packets received */
+	u32 q_num; /* queue index */
+	u32 ntfy_id; /* notification block index */
+	struct gve_queue_resources *q_resources; /* head and tail pointer idx */
+	dma_addr_t q_resources_bus; /* dma address for the queue resources */
+	struct u64_stats_sync statss; /* sync stats for 32bit archs */
+};
+
+/* A TX desc ring entry */
+union gve_tx_desc {
+	struct gve_tx_pkt_desc pkt; /* first desc for a packet */
+	struct gve_tx_seg_desc seg; /* subsequent descs for a packet */
+};
+
+/* Tracks the memory in the fifo occupied by a segment of a packet */
+struct gve_tx_iovec {
+	u32 iov_offset; /* offset into this segment */
+	u32 iov_len; /* length */
+	u32 iov_padding; /* padding associated with this segment */
+};
+
+/* Tracks the memory in the fifo occupied by the skb. Mapped 1:1 to a desc
+ * ring entry but only used for a pkt_desc not a seg_desc
+ */
+struct gve_tx_buffer_state {
+	struct sk_buff *skb; /* skb for this pkt */
+	struct gve_tx_iovec iov[GVE_TX_MAX_IOVEC]; /* segments of this pkt */
+};
+
+/* A TX buffer - each queue has one */
+struct gve_tx_fifo {
+	void *base; /* address of base of FIFO */
+	u32 size; /* total size */
+	atomic_t available; /* how much space is still available */
+	u32 head; /* offset to write at */
+	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 */
+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 */
+
+	/* Cacheline 1 -- Accessed & dirtied during gve_clean_tx_done */
+	__be32 last_nic_done ____cacheline_aligned; /* NIC tail pointer */
+	u64 pkt_done; /* free-running - total packets completed */
+	u64 bytes_done; /* free-running - total bytes completed */
+
+	/* Cacheline 2 -- Read-mostly fields */
+	union gve_tx_desc *desc ____cacheline_aligned;
+	struct gve_tx_buffer_state *info; /* Maps 1:1 to a desc */
+	struct netdev_queue *netdev_txq;
+	struct gve_queue_resources *q_resources; /* head and tail pointer idx */
+	u32 mask; /* masks req and done down to queue size */
+
+	/* Slow-path fields */
+	u32 q_num ____cacheline_aligned; /* queue idx */
+	u32 stop_queue; /* count of queue stops */
+	u32 wake_queue; /* count of queue wakes */
+	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 */
+	struct u64_stats_sync statss; /* sync stats for 32bit archs */
+} ____cacheline_aligned;
+
+/* Wraps the info for one irq including the napi struct and the queues
+ * associated with that irq.
+ */
 struct gve_notify_block {
 	__be32 irq_db_index; /* idx into Bar2 - set by device, must be 1st */
 	char name[IFNAMSIZ + 16]; /* name registered with the kernel */
 	struct napi_struct napi; /* kernel napi struct for this block */
 	struct gve_priv *priv;
+	struct gve_tx_ring *tx; /* tx rings on this block */
+	struct gve_rx_ring *rx; /* rx rings on this block */
 } ____cacheline_aligned;
 
+/* Tracks allowed and current queue settings */
+struct gve_queue_config {
+	u16 max_queues;
+	u16 num_queues; /* current */
+};
+
+/* Tracks the available and used qpl IDs */
+struct gve_qpl_config {
+	u32 qpl_map_size; /* map memory size */
+	unsigned long *qpl_id_map; /* bitmap of used qpl ids */
+};
+
 struct gve_priv {
 	struct net_device *dev;
+	struct gve_tx_ring *tx; /* array of tx_cfg.num_queues */
+	struct gve_rx_ring *rx; /* array of rx_cfg.num_queues */
+	struct gve_queue_page_list *qpls; /* array of num qpls */
 	struct gve_notify_block *ntfy_blocks; /* array of num_ntfy_blks */
 	dma_addr_t ntfy_block_bus;
 	struct msix_entry *msix_vectors; /* array of num_ntfy_blks + 1 */
@@ -41,14 +177,28 @@ struct gve_priv {
 	dma_addr_t counter_array_bus;
 
 	u16 num_event_counters;
+	u16 tx_desc_cnt; /* num desc per ring */
+	u16 rx_desc_cnt; /* num desc per ring */
+	u16 tx_pages_per_qpl; /* tx buffer length */
+	u16 rx_pages_per_qpl; /* rx buffer length */
+	u64 max_registered_pages;
+	u64 num_registered_pages; /* num pages registered with NIC */
+	u32 rx_copybreak; /* copy packets smaller than this */
+	u16 default_num_queues; /* default num queues to set up */
 
+	struct gve_queue_config tx_cfg;
+	struct gve_queue_config rx_cfg;
+	struct gve_qpl_config qpl_cfg; /* map used QPL ids */
 	u32 num_ntfy_blks; /* spilt between TX and RX so must be even */
 
 	struct gve_registers __iomem *reg_bar0; /* see gve_register.h */
 	__be32 __iomem *db_bar2; /* "array" of doorbells */
 	u32 msg_enable;	/* level for netif* netdev print macros	*/
 	struct pci_dev *pdev;
 
+	/* metrics */
+	u32 tx_timeo_cnt;
+
 	/* Admin queue - see gve_adminq.h*/
 	union gve_adminq_command *adminq;
 	dma_addr_t adminq_bus_addr;
@@ -132,4 +282,112 @@ static inline __be32 __iomem *gve_irq_doorbell(struct gve_priv *priv,
 {
 	return &priv->db_bar2[be32_to_cpu(block->irq_db_index)];
 }
+
+/* Returns the index into ntfy_blocks of the given tx ring's block
+ */
+static inline u32 gve_tx_idx_to_ntfy(struct gve_priv *priv, u32 queue_idx)
+{
+	return queue_idx;
+}
+
+/* Returns the index into ntfy_blocks of the given rx ring's block
+ */
+static inline u32 gve_rx_idx_to_ntfy(struct gve_priv *priv, u32 queue_idx)
+{
+	return (priv->num_ntfy_blks / 2) + queue_idx;
+}
+
+/* Returns the number of tx queue page lists
+ */
+static inline u32 gve_num_tx_qpls(struct gve_priv *priv)
+{
+	return priv->tx_cfg.num_queues;
+}
+
+/* Returns the number of rx queue page lists
+ */
+static inline u32 gve_num_rx_qpls(struct gve_priv *priv)
+{
+	return priv->rx_cfg.num_queues;
+}
+
+/* Returns a pointer to the next available tx qpl in the list of qpls
+ */
+static inline
+struct gve_queue_page_list *gve_assign_tx_qpl(struct gve_priv *priv)
+{
+	int id = find_first_zero_bit(priv->qpl_cfg.qpl_id_map,
+				     priv->qpl_cfg.qpl_map_size);
+
+	/* we are out of tx qpls */
+	if (id >= gve_num_tx_qpls(priv))
+		return NULL;
+
+	set_bit(id, priv->qpl_cfg.qpl_id_map);
+	return &priv->qpls[id];
+}
+
+/* Returns a pointer to the next available rx qpl in the list of qpls
+ */
+static inline
+struct gve_queue_page_list *gve_assign_rx_qpl(struct gve_priv *priv)
+{
+	int id = find_next_zero_bit(priv->qpl_cfg.qpl_id_map,
+				    priv->qpl_cfg.qpl_map_size,
+				    gve_num_tx_qpls(priv));
+
+	/* we are out of rx qpls */
+	if (id == priv->qpl_cfg.qpl_map_size)
+		return NULL;
+
+	set_bit(id, priv->qpl_cfg.qpl_id_map);
+	return &priv->qpls[id];
+}
+
+/* Unassigns the qpl with the given id
+ */
+static inline void gve_unassign_qpl(struct gve_priv *priv, int id)
+{
+	clear_bit(id, priv->qpl_cfg.qpl_id_map);
+}
+
+/* Returns the correct dma direction for tx and rx qpls
+ */
+static inline enum dma_data_direction gve_qpl_dma_dir(struct gve_priv *priv,
+						      int id)
+{
+	if (id < gve_num_tx_qpls(priv))
+		return DMA_TO_DEVICE;
+	else
+		return DMA_FROM_DEVICE;
+}
+
+/* Returns true if the max mtu allows page recycling */
+static inline bool gve_can_recycle_pages(struct net_device *dev)
+{
+	/* We can't recycle the pages if we can't fit a packet into half a
+	 * page.
+	 */
+	return dev->max_mtu <= PAGE_SIZE / 2;
+}
+
+/* buffers */
+int gve_alloc_page(struct device *dev, struct page **page, dma_addr_t *dma,
+		   enum dma_data_direction);
+void gve_free_page(struct device *dev, struct page *page, dma_addr_t dma,
+		   enum dma_data_direction);
+/* tx handling */
+netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev);
+bool gve_tx_poll(struct gve_notify_block *block, int budget);
+int gve_tx_alloc_rings(struct gve_priv *priv);
+void gve_tx_free_rings(struct gve_priv *priv);
+__be32 gve_tx_load_event_counter(struct gve_priv *priv,
+				 struct gve_tx_ring *tx);
+/* rx handling */
+void gve_rx_write_doorbell(struct gve_priv *priv, struct gve_rx_ring *rx);
+bool gve_rx_poll(struct gve_notify_block *block, int budget);
+int gve_rx_alloc_rings(struct gve_priv *priv);
+void gve_rx_free_rings(struct gve_priv *priv);
+bool gve_clean_rx_done(struct gve_rx_ring *rx, int budget,
+		       netdev_features_t feat);
 #endif /* _GVE_H_ */