/*
 * 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; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#ifndef __XEN_NETBACK__COMMON_H__
#define __XEN_NETBACK__COMMON_H__

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/io.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/wait.h>
#include <linux/sched.h>

#include <xen/interface/io/netif.h>
#include <xen/interface/grant_table.h>
#include <xen/grant_table.h>
#include <xen/xenbus.h>
#include <xen/page.h>
#include <linux/debugfs.h>

typedef unsigned int pending_ring_idx_t;
#define INVALID_PENDING_RING_IDX (~0U)

struct pending_tx_info {
        struct xen_netif_tx_request req; /* tx request */
        unsigned int extra_count;
        /* Callback data for released SKBs. The callback is always
         * xenvif_zerocopy_callback, desc contains the pending_idx, which is
         * also an index in pending_tx_info array. It is initialized in
         * xenvif_alloc and it never changes.
         * skb_shinfo(skb)->destructor_arg points to the first mapped slot's
         * callback_struct in this array of struct pending_tx_info's, then ctx
         * to the next, or NULL if there is no more slot for this skb.
         * ubuf_to_vif is a helper which finds the struct xenvif from a pointer
         * to this field.
         */
        struct ubuf_info callback_struct;
};

#define XEN_NETIF_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, XEN_PAGE_SIZE)
#define XEN_NETIF_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, XEN_PAGE_SIZE)

struct xenvif_rx_meta {
        int id;
        int size;
        int gso_type;
        int gso_size;
};

#define GSO_BIT(type) \
        (1 << XEN_NETIF_GSO_TYPE_ ## type)

/* Discriminate from any valid pending_idx value. */
#define INVALID_PENDING_IDX 0xFFFF

#define MAX_BUFFER_OFFSET XEN_PAGE_SIZE

#define MAX_PENDING_REQS XEN_NETIF_TX_RING_SIZE

/* The maximum number of frags is derived from the size of a grant (same
 * as a Xen page size for now).
 */
#define MAX_XEN_SKB_FRAGS (65536 / XEN_PAGE_SIZE + 1)

#define NETBACK_INVALID_HANDLE -1

/* To avoid confusion, we define XEN_NETBK_LEGACY_SLOTS_MAX indicating
 * the maximum slots a valid packet can use. Now this value is defined
 * to be XEN_NETIF_NR_SLOTS_MIN, which is supposed to be supported by
 * all backend.
 */
#define XEN_NETBK_LEGACY_SLOTS_MAX XEN_NETIF_NR_SLOTS_MIN

/* Queue name is interface name with "-qNNN" appended */
#define QUEUE_NAME_SIZE (IFNAMSIZ + 5)

/* IRQ name is queue name with "-tx" or "-rx" appended */
#define IRQ_NAME_SIZE (QUEUE_NAME_SIZE + 3)

struct xenvif;

struct xenvif_stats {
        /* Stats fields to be updated per-queue.
         * A subset of struct net_device_stats that contains only the
         * fields that are updated in netback.c for each queue.
         */
        u64 rx_bytes;
        u64 rx_packets;
        u64 tx_bytes;
        u64 tx_packets;

        /* Additional stats used by xenvif */
        unsigned long rx_gso_checksum_fixup;
        unsigned long tx_zerocopy_sent;
        unsigned long tx_zerocopy_success;
        unsigned long tx_zerocopy_fail;
        unsigned long tx_frag_overflow;
};

#define COPY_BATCH_SIZE 64

struct xenvif_copy_state {
        struct gnttab_copy op[COPY_BATCH_SIZE];
        RING_IDX idx[COPY_BATCH_SIZE];
        unsigned int num;
        struct sk_buff_head *completed;
};

struct xenvif_queue { /* Per-queue data for xenvif */
        unsigned int id; /* Queue ID, 0-based */
        char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */
        struct xenvif *vif; /* Parent VIF */

        /*
         * TX/RX common EOI handling.
         * When feature-split-event-channels = 0, interrupt handler sets
         * NETBK_COMMON_EOI, otherwise NETBK_RX_EOI and NETBK_TX_EOI are set
         * by the RX and TX interrupt handlers.
         * RX and TX handler threads will issue an EOI when either
         * NETBK_COMMON_EOI or their specific bits (NETBK_RX_EOI or
         * NETBK_TX_EOI) are set and they will reset those bits.
         */
        atomic_t eoi_pending;
#define NETBK_RX_EOI            0x01
#define NETBK_TX_EOI            0x02
#define NETBK_COMMON_EOI        0x04

        /* Use NAPI for guest TX */
        struct napi_struct napi;
        /* When feature-split-event-channels = 0, tx_irq = rx_irq. */
        unsigned int tx_irq;
        /* Only used when feature-split-event-channels = 1 */
        char tx_irq_name[IRQ_NAME_SIZE]; /* DEVNAME-qN-tx */
        struct xen_netif_tx_back_ring tx;
        struct sk_buff_head tx_queue;
        struct page *mmap_pages[MAX_PENDING_REQS];
        pending_ring_idx_t pending_prod;
        pending_ring_idx_t pending_cons;
        u16 pending_ring[MAX_PENDING_REQS];
        struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
        grant_handle_t grant_tx_handle[MAX_PENDING_REQS];

        struct gnttab_copy tx_copy_ops[MAX_PENDING_REQS];
        struct gnttab_map_grant_ref tx_map_ops[MAX_PENDING_REQS];
        struct gnttab_unmap_grant_ref tx_unmap_ops[MAX_PENDING_REQS];
        /* passed to gnttab_[un]map_refs with pages under (un)mapping */
        struct page *pages_to_map[MAX_PENDING_REQS];
        struct page *pages_to_unmap[MAX_PENDING_REQS];

        /* This prevents zerocopy callbacks  to race over dealloc_ring */
        spinlock_t callback_lock;
        /* This prevents dealloc thread and NAPI instance to race over response
         * creation and pending_ring in xenvif_idx_release. In xenvif_tx_err
         * it only protect response creation
         */
        spinlock_t response_lock;
        pending_ring_idx_t dealloc_prod;
        pending_ring_idx_t dealloc_cons;
        u16 dealloc_ring[MAX_PENDING_REQS];
        struct task_struct *dealloc_task;
        wait_queue_head_t dealloc_wq;
        atomic_t inflight_packets;

        /* Use kthread for guest RX */
        struct task_struct *task;
        wait_queue_head_t wq;
        /* When feature-split-event-channels = 0, tx_irq = rx_irq. */
        unsigned int rx_irq;
        /* Only used when feature-split-event-channels = 1 */
        char rx_irq_name[IRQ_NAME_SIZE]; /* DEVNAME-qN-rx */
        struct xen_netif_rx_back_ring rx;
        struct sk_buff_head rx_queue;

        unsigned int rx_queue_max;
        unsigned int rx_queue_len;
        unsigned long last_rx_time;
        bool stalled;

        struct xenvif_copy_state rx_copy;

        /* Transmit shaping: allow 'credit_bytes' every 'credit_usec'. */
        unsigned long   credit_bytes;
        unsigned long   credit_usec;
        unsigned long   remaining_credit;
        struct timer_list credit_timeout;
        u64 credit_window_start;
        bool rate_limited;

        /* Statistics */
        struct xenvif_stats stats;
};

enum state_bit_shift {
        /* This bit marks that the vif is connected */
        VIF_STATUS_CONNECTED,
};

struct xenvif_mcast_addr {
        struct list_head entry;
        struct rcu_head rcu;
        u8 addr[6];
};

#define XEN_NETBK_MCAST_MAX 64

#define XEN_NETBK_MAX_HASH_KEY_SIZE 40
#define XEN_NETBK_MAX_HASH_MAPPING_SIZE 128
#define XEN_NETBK_HASH_TAG_SIZE 40

struct xenvif_hash_cache_entry {
        struct list_head link;
        struct rcu_head rcu;
        u8 tag[XEN_NETBK_HASH_TAG_SIZE];
        unsigned int len;
        u32 val;
        int seq;
};

struct xenvif_hash_cache {
        spinlock_t lock;
        struct list_head list;
        unsigned int count;
        atomic_t seq;
};

struct xenvif_hash {
        unsigned int alg;
        u32 flags;
        bool mapping_sel;
        u8 key[XEN_NETBK_MAX_HASH_KEY_SIZE];
        u32 mapping[2][XEN_NETBK_MAX_HASH_MAPPING_SIZE];
        unsigned int size;
        struct xenvif_hash_cache cache;
};

struct backend_info {
        struct xenbus_device *dev;
        struct xenvif *vif;

        /* This is the state that will be reflected in xenstore when any
         * active hotplug script completes.
         */
        enum xenbus_state state;

        enum xenbus_state frontend_state;
        struct xenbus_watch hotplug_status_watch;
        u8 have_hotplug_status_watch:1;

        const char *hotplug_script;
};

struct xenvif {
        /* Unique identifier for this interface. */
        domid_t          domid;
        unsigned int     handle;

        u8               fe_dev_addr[6];
        struct list_head fe_mcast_addr;
        unsigned int     fe_mcast_count;

        /* Frontend feature information. */
        int gso_mask;

        u8 can_sg:1;
        u8 ip_csum:1;
        u8 ipv6_csum:1;
        u8 multicast_control:1;

        /* headroom requested by xen-netfront */
        u16 xdp_headroom;

        /* Is this interface disabled? True when backend discovers
         * frontend is rogue.
         */
        bool disabled;
        unsigned long status;
        unsigned long drain_timeout;
        unsigned long stall_timeout;

        /* Queues */
        struct xenvif_queue *queues;
        unsigned int num_queues; /* active queues, resource allocated */
        unsigned int stalled_queues;

        struct xenvif_hash hash;

        struct xenbus_watch credit_watch;
        struct xenbus_watch mcast_ctrl_watch;

        struct backend_info *be;

        spinlock_t lock;

#ifdef CONFIG_DEBUG_FS
        struct dentry *xenvif_dbg_root;
#endif

        struct xen_netif_ctrl_back_ring ctrl;
        unsigned int ctrl_irq;

        /* Miscellaneous private stuff. */
        struct net_device *dev;
};

struct xenvif_rx_cb {
        unsigned long expires;
        int meta_slots_used;
};

#define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)

static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
{
        return to_xenbus_device(vif->dev->dev.parent);
}

void xenvif_tx_credit_callback(struct timer_list *t);

struct xenvif *xenvif_alloc(struct device *parent,
                            domid_t domid,
                            unsigned int handle);

int xenvif_init_queue(struct xenvif_queue *queue);
void xenvif_deinit_queue(struct xenvif_queue *queue);

int xenvif_connect_data(struct xenvif_queue *queue,
                        unsigned long tx_ring_ref,
                        unsigned long rx_ring_ref,
                        unsigned int tx_evtchn,
                        unsigned int rx_evtchn);
void xenvif_disconnect_data(struct xenvif *vif);
int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
                        unsigned int evtchn);
void xenvif_disconnect_ctrl(struct xenvif *vif);
void xenvif_free(struct xenvif *vif);

int xenvif_xenbus_init(void);
void xenvif_xenbus_fini(void);

int xenvif_schedulable(struct xenvif *vif);

int xenvif_queue_stopped(struct xenvif_queue *queue);
void xenvif_wake_queue(struct xenvif_queue *queue);

/* (Un)Map communication rings. */
void xenvif_unmap_frontend_data_rings(struct xenvif_queue *queue);
int xenvif_map_frontend_data_rings(struct xenvif_queue *queue,
                                   grant_ref_t tx_ring_ref,
                                   grant_ref_t rx_ring_ref);

/* Check for SKBs from frontend and schedule backend processing */
void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue);

/* Prevent the device from generating any further traffic. */
void xenvif_carrier_off(struct xenvif *vif);

int xenvif_tx_action(struct xenvif_queue *queue, int budget);

int xenvif_kthread_guest_rx(void *data);
void xenvif_kick_thread(struct xenvif_queue *queue);

int xenvif_dealloc_kthread(void *data);

irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data);

bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread);
void xenvif_rx_action(struct xenvif_queue *queue);
void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);

void xenvif_carrier_on(struct xenvif *vif);

/* Callback from stack when TX packet can be released */
void xenvif_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *ubuf,
                              bool zerocopy_success);

/* Unmap a pending page and release it back to the guest */
void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx);

static inline pending_ring_idx_t nr_pending_reqs(struct xenvif_queue *queue)
{
        return MAX_PENDING_REQS -
                queue->pending_prod + queue->pending_cons;
}

irqreturn_t xenvif_interrupt(int irq, void *dev_id);

extern bool separate_tx_rx_irq;
extern bool provides_xdp_headroom;

extern unsigned int rx_drain_timeout_msecs;
extern unsigned int rx_stall_timeout_msecs;
extern unsigned int xenvif_max_queues;
extern unsigned int xenvif_hash_cache_size;

#ifdef CONFIG_DEBUG_FS
extern struct dentry *xen_netback_dbg_root;
#endif

void xenvif_skb_zerocopy_prepare(struct xenvif_queue *queue,
                                 struct sk_buff *skb);
void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue);

/* Multicast control */
bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr);
void xenvif_mcast_addr_list_free(struct xenvif *vif);

/* Hash */
void xenvif_init_hash(struct xenvif *vif);
void xenvif_deinit_hash(struct xenvif *vif);

u32 xenvif_set_hash_alg(struct xenvif *vif, u32 alg);
u32 xenvif_get_hash_flags(struct xenvif *vif, u32 *flags);
u32 xenvif_set_hash_flags(struct xenvif *vif, u32 flags);
u32 xenvif_set_hash_key(struct xenvif *vif, u32 gref, u32 len);
u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size);
u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
                            u32 off);

void xenvif_set_skb_hash(struct xenvif *vif, struct sk_buff *skb);

#ifdef CONFIG_DEBUG_FS
void xenvif_dump_hash_info(struct xenvif *vif, struct seq_file *m);
#endif

#endif /* __XEN_NETBACK__COMMON_H__ */