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    Subject[patch 24/28]xen: Add the Xen virtual network device driver.
    The network device frontend driver allows the kernel to access network
    devices exported exported by a virtual machine containing a physical
    network device driver.



    Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
    Signed-off-by: Chris Wright <chrisw@sous-sol.org>
    Cc: Ian Pratt <ian.pratt@xensource.com>
    Cc: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
    Cc: Jeff Garzik <jeff@garzik.org>
    Cc: Stephen Hemminger <shemminger@linux-foundation.org>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Rusty Russell <rusty@rustcorp.com.au>
    Cc: Herbert Xu <herbert@gondor.apana.org.au>
    Cc: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
    Cc: netdev@vger.kernel.org

    ---
    drivers/net/Kconfig | 12
    drivers/net/Makefile | 2
    drivers/net/xen-netfront.c | 1995 ++++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 2009 insertions(+)

    ===================================================================
    --- a/drivers/net/Kconfig
    +++ b/drivers/net/Kconfig
    @@ -2507,6 +2507,18 @@ source "drivers/atm/Kconfig"

    source "drivers/s390/net/Kconfig"

    +config XEN_NETDEV_FRONTEND
    + tristate "Xen network device frontend driver"
    + depends on XEN
    + default y
    + help
    + The network device frontend driver allows the kernel to
    + access network devices exported exported by a virtual
    + machine containing a physical network device driver. The
    + frontend driver is intended for unprivileged guest domains;
    + if you are compiling a kernel for a Xen guest, you almost
    + certainly want to enable this.
    +
    config ISERIES_VETH
    tristate "iSeries Virtual Ethernet driver support"
    depends on PPC_ISERIES
    ===================================================================
    --- a/drivers/net/Makefile
    +++ b/drivers/net/Makefile
    @@ -218,3 +218,5 @@ obj-$(CONFIG_FS_ENET) += fs_enet/
    obj-$(CONFIG_FS_ENET) += fs_enet/

    obj-$(CONFIG_NETXEN_NIC) += netxen/
    +
    +obj-$(CONFIG_XEN_NETDEV_FRONTEND) += xen-netfront.o
    ===================================================================
    --- /dev/null
    +++ b/drivers/net/xen-netfront.c
    @@ -0,0 +1,1995 @@
    +/*
    + * Virtual network driver for conversing with remote driver backends.
    + *
    + * Copyright (c) 2002-2005, K A Fraser
    + * Copyright (c) 2005, XenSource Ltd
    + *
    + * 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.
    + */
    +
    +#include <linux/module.h>
    +#include <linux/kernel.h>
    +#include <linux/netdevice.h>
    +#include <linux/etherdevice.h>
    +#include <linux/skbuff.h>
    +#include <linux/ethtool.h>
    +#include <linux/if_ether.h>
    +#include <linux/tcp.h>
    +#include <linux/udp.h>
    +#include <linux/moduleparam.h>
    +#include <linux/mm.h>
    +#include <net/ip.h>
    +
    +#include <xen/xenbus.h>
    +#include <xen/events.h>
    +#include <xen/page.h>
    +#include <xen/grant_table.h>
    +
    +#include <xen/interface/io/netif.h>
    +#include <xen/interface/memory.h>
    +#include <xen/interface/grant_table.h>
    +
    +static struct ethtool_ops xennet_ethtool_ops;
    +
    +struct netfront_cb {
    + struct page *page;
    + unsigned offset;
    +};
    +
    +#define NETFRONT_SKB_CB(skb) ((struct netfront_cb *)((skb)->cb))
    +
    +/*
    + * Mutually-exclusive module options to select receive data path:
    + * copy : Packets are copied by network backend into local memory
    + * flip : Page containing packet data is transferred to our ownership
    + * For fully-virtualised guests there is no option - copying must be used.
    + * For paravirtualised guests, flipping is the default.
    + */
    +typedef enum rx_mode {
    + RX_COPY = 0,
    + RX_FLIP = 1,
    +} rx_mode_t;
    +
    +static enum rx_mode rx_mode = RX_FLIP;
    +
    +#define param_check_rx_mode_t(name, p) __param_check(name, p, rx_mode_t)
    +
    +static int param_set_rx_mode_t(const char *val, struct kernel_param *kp)
    +{
    + enum rx_mode *rxmp = kp->arg;
    + int ret = 0;
    +
    + if (strcmp(val, "copy") == 0)
    + *rxmp = RX_COPY;
    + else if (strcmp(val, "flip") == 0)
    + *rxmp = RX_FLIP;
    + else
    + ret = -EINVAL;
    +
    + return ret;
    +}
    +
    +static int param_get_rx_mode_t(char *buffer, struct kernel_param *kp)
    +{
    + enum rx_mode *rxmp = kp->arg;
    +
    + return sprintf(buffer, "%s", *rxmp == RX_COPY ? "copy" : "flip");
    +}
    +
    +MODULE_PARM_DESC(rx_mode, "How to get packets from card: \"copy\" or \"flip\"");
    +module_param(rx_mode, rx_mode_t, 0400);
    +
    +#define RX_COPY_THRESHOLD 256
    +
    +#define GRANT_INVALID_REF 0
    +
    +#define NET_TX_RING_SIZE __RING_SIZE((struct xen_netif_tx_sring *)0, PAGE_SIZE)
    +#define NET_RX_RING_SIZE __RING_SIZE((struct xen_netif_rx_sring *)0, PAGE_SIZE)
    +#define TX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
    +
    +struct netfront_info {
    + struct list_head list;
    + struct net_device *netdev;
    +
    + struct net_device_stats stats;
    +
    + struct xen_netif_tx_front_ring tx;
    + struct xen_netif_rx_front_ring rx;
    +
    + spinlock_t tx_lock;
    + spinlock_t rx_lock;
    +
    + unsigned int evtchn;
    + unsigned int copying_receiver;
    +
    + /* Receive-ring batched refills. */
    +#define RX_MIN_TARGET 8
    +#define RX_DFL_MIN_TARGET 64
    +#define RX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
    + unsigned rx_min_target, rx_max_target, rx_target;
    + struct sk_buff_head rx_batch;
    +
    + struct timer_list rx_refill_timer;
    +
    + /*
    + * {tx,rx}_skbs store outstanding skbuffs. Free tx_skb entries
    + * are linked from tx_skb_freelist through skb_entry.link.
    + *
    + * NB. Freelist index entries are always going to be less than
    + * PAGE_OFFSET, whereas pointers to skbs will always be equal or
    + * greater than PAGE_OFFSET: we use this property to distinguish
    + * them.
    + */
    + union skb_entry {
    + struct sk_buff *skb;
    + unsigned link;
    + } tx_skbs[NET_TX_RING_SIZE];;
    + grant_ref_t gref_tx_head;
    + grant_ref_t grant_tx_ref[NET_TX_RING_SIZE];
    + unsigned tx_skb_freelist;
    +
    + struct sk_buff *rx_skbs[NET_RX_RING_SIZE];
    + grant_ref_t gref_rx_head;
    + grant_ref_t grant_rx_ref[NET_RX_RING_SIZE];
    +
    + struct xenbus_device *xbdev;
    + int tx_ring_ref;
    + int rx_ring_ref;
    +
    + unsigned long rx_pfn_array[NET_RX_RING_SIZE];
    + struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1];
    + struct mmu_update rx_mmu[NET_RX_RING_SIZE];
    +};
    +
    +struct netfront_rx_info {
    + struct xen_netif_rx_response rx;
    + struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
    +};
    +
    +/*
    + * Access macros for acquiring freeing slots in tx_skbs[].
    + */
    +
    +static void add_id_to_freelist(unsigned *head, union skb_entry *list, unsigned short id)
    +{
    + list[id].link = *head;
    + *head = id;
    +}
    +
    +static unsigned short get_id_from_freelist(unsigned *head, union skb_entry *list)
    +{
    + unsigned int id = *head;
    + *head = list[id].link;
    + return id;
    +}
    +
    +static int xennet_rxidx(RING_IDX idx)
    +{
    + return idx & (NET_RX_RING_SIZE - 1);
    +}
    +
    +static struct sk_buff *xennet_get_rx_skb(struct netfront_info *np,
    + RING_IDX ri)
    +{
    + int i = xennet_rxidx(ri);
    + struct sk_buff *skb = np->rx_skbs[i];
    + np->rx_skbs[i] = NULL;
    + return skb;
    +}
    +
    +static grant_ref_t xennet_get_rx_ref(struct netfront_info *np,
    + RING_IDX ri)
    +{
    + int i = xennet_rxidx(ri);
    + grant_ref_t ref = np->grant_rx_ref[i];
    + np->grant_rx_ref[i] = GRANT_INVALID_REF;
    + return ref;
    +}
    +
    +#ifdef CONFIG_SYSFS
    +static int xennet_sysfs_addif(struct net_device *netdev);
    +static void xennet_sysfs_delif(struct net_device *netdev);
    +#else /* !CONFIG_SYSFS */
    +#define xennet_sysfs_addif(dev) (0)
    +#define xennet_sysfs_delif(dev) do { } while(0)
    +#endif
    +
    +static int xennet_can_sg(struct net_device *dev)
    +{
    + return dev->features & NETIF_F_SG;
    +}
    +
    +
    +static void rx_refill_timeout(unsigned long data)
    +{
    + struct net_device *dev = (struct net_device *)data;
    + netif_rx_schedule(dev);
    +}
    +
    +static int netfront_tx_slot_available(struct netfront_info *np)
    +{
    + return ((np->tx.req_prod_pvt - np->tx.rsp_cons) <
    + (TX_MAX_TARGET - MAX_SKB_FRAGS - 2));
    +}
    +
    +static void xennet_maybe_wake_tx(struct net_device *dev)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    +
    + if (unlikely(netif_queue_stopped(dev)) &&
    + netfront_tx_slot_available(np) &&
    + likely(netif_running(dev)))
    + netif_wake_queue(dev);
    +}
    +
    +static void xennet_alloc_rx_buffers(struct net_device *dev)
    +{
    + unsigned short id;
    + struct netfront_info *np = netdev_priv(dev);
    + struct sk_buff *skb;
    + struct page *page;
    + int i, batch_target, notify;
    + RING_IDX req_prod = np->rx.req_prod_pvt;
    + struct xen_memory_reservation reservation;
    + grant_ref_t ref;
    + unsigned long pfn;
    + void *vaddr;
    + int nr_flips;
    + struct xen_netif_rx_request *req;
    +
    + if (unlikely(!netif_carrier_ok(dev)))
    + return;
    +
    + /*
    + * Allocate skbuffs greedily, even though we batch updates to the
    + * receive ring. This creates a less bursty demand on the memory
    + * allocator, so should reduce the chance of failed allocation requests
    + * both for ourself and for other kernel subsystems.
    + */
    + batch_target = np->rx_target - (req_prod - np->rx.rsp_cons);
    + for (i = skb_queue_len(&np->rx_batch); i < batch_target; i++) {
    + skb = __netdev_alloc_skb(dev, RX_COPY_THRESHOLD,
    + GFP_ATOMIC | __GFP_NOWARN);
    + if (unlikely(!skb))
    + goto no_skb;
    +
    + page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
    + if (!page) {
    + kfree_skb(skb);
    +no_skb:
    + /* Any skbuffs queued for refill? Force them out. */
    + if (i != 0)
    + goto refill;
    + /* Could not allocate any skbuffs. Try again later. */
    + mod_timer(&np->rx_refill_timer,
    + jiffies + (HZ/10));
    + break;
    + }
    +
    + skb_shinfo(skb)->frags[0].page = page;
    + skb_shinfo(skb)->nr_frags = 1;
    + __skb_queue_tail(&np->rx_batch, skb);
    + }
    +
    + /* Is the batch large enough to be worthwhile? */
    + if (i < (np->rx_target/2)) {
    + if (req_prod > np->rx.sring->req_prod)
    + goto push;
    + return;
    + }
    +
    + /* Adjust our fill target if we risked running out of buffers. */
    + if (((req_prod - np->rx.sring->rsp_prod) < (np->rx_target / 4)) &&
    + ((np->rx_target *= 2) > np->rx_max_target))
    + np->rx_target = np->rx_max_target;
    +
    + refill:
    + for (nr_flips = i = 0; ; i++) {
    + if ((skb = __skb_dequeue(&np->rx_batch)) == NULL)
    + break;
    +
    + skb->dev = dev;
    +
    + id = xennet_rxidx(req_prod + i);
    +
    + BUG_ON(np->rx_skbs[id]);
    + np->rx_skbs[id] = skb;
    +
    + ref = gnttab_claim_grant_reference(&np->gref_rx_head);
    + BUG_ON((signed short)ref < 0);
    + np->grant_rx_ref[id] = ref;
    +
    + pfn = page_to_pfn(skb_shinfo(skb)->frags[0].page);
    + vaddr = page_address(skb_shinfo(skb)->frags[0].page);
    +
    + req = RING_GET_REQUEST(&np->rx, req_prod + i);
    + if (!np->copying_receiver) {
    + gnttab_grant_foreign_transfer_ref(ref,
    + np->xbdev->otherend_id,
    + pfn);
    + np->rx_pfn_array[nr_flips] = pfn_to_mfn(pfn);
    + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
    + /* Remove this page before passing
    + * back to Xen. */
    + set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
    + MULTI_update_va_mapping(np->rx_mcl+i,
    + (unsigned long)vaddr,
    + __pte(0), 0);
    + }
    + nr_flips++;
    + } else {
    + gnttab_grant_foreign_access_ref(ref,
    + np->xbdev->otherend_id,
    + pfn_to_mfn(pfn),
    + 0);
    + }
    +
    + req->id = id;
    + req->gref = ref;
    + }
    +
    + if (nr_flips != 0) {
    + reservation.extent_start = np->rx_pfn_array;
    + reservation.nr_extents = nr_flips;
    + reservation.extent_order = 0;
    + reservation.address_bits = 0;
    + reservation.domid = DOMID_SELF;
    +
    + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
    + /* After all PTEs have been zapped, flush the TLB. */
    + np->rx_mcl[i-1].args[MULTI_UVMFLAGS_INDEX] =
    + UVMF_TLB_FLUSH|UVMF_ALL;
    +
    + /* Give away a batch of pages. */
    + np->rx_mcl[i].op = __HYPERVISOR_memory_op;
    + np->rx_mcl[i].args[0] = XENMEM_decrease_reservation;
    + np->rx_mcl[i].args[1] = (unsigned long)&reservation;
    +
    + /* Zap PTEs and give away pages in one big
    + * multicall. */
    + (void)HYPERVISOR_multicall(np->rx_mcl, i+1);
    +
    + /* Check return status of HYPERVISOR_memory_op(). */
    + if (unlikely(np->rx_mcl[i].result != i))
    + panic("Unable to reduce memory reservation\n");
    + } else {
    + if (HYPERVISOR_memory_op(XENMEM_decrease_reservation,
    + &reservation) != i)
    + panic("Unable to reduce memory reservation\n");
    + }
    + } else {
    + wmb();
    + }
    +
    + /* Above is a suitable barrier to ensure backend will see requests. */
    + np->rx.req_prod_pvt = req_prod + i;
    + push:
    + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->rx, notify);
    + if (notify)
    + notify_remote_via_irq(np->netdev->irq);
    +}
    +
    +static int xennet_open(struct net_device *dev)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    +
    + memset(&np->stats, 0, sizeof(np->stats));
    +
    + spin_lock_bh(&np->rx_lock);
    + if (netif_carrier_ok(dev)) {
    + xennet_alloc_rx_buffers(dev);
    + np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
    + if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
    + netif_rx_schedule(dev);
    + }
    + spin_unlock_bh(&np->rx_lock);
    +
    + xennet_maybe_wake_tx(dev);
    +
    + return 0;
    +}
    +
    +static void xennet_tx_buf_gc(struct net_device *dev)
    +{
    + RING_IDX cons, prod;
    + unsigned short id;
    + struct netfront_info *np = netdev_priv(dev);
    + struct sk_buff *skb;
    +
    + BUG_ON(!netif_carrier_ok(dev));
    +
    + do {
    + prod = np->tx.sring->rsp_prod;
    + rmb(); /* Ensure we see responses up to 'rp'. */
    +
    + for (cons = np->tx.rsp_cons; cons != prod; cons++) {
    + struct xen_netif_tx_response *txrsp;
    +
    + txrsp = RING_GET_RESPONSE(&np->tx, cons);
    + if (txrsp->status == NETIF_RSP_NULL)
    + continue;
    +
    + id = txrsp->id;
    + skb = np->tx_skbs[id].skb;
    + if (unlikely(gnttab_query_foreign_access(
    + np->grant_tx_ref[id]) != 0)) {
    + printk(KERN_ALERT "xennet_tx_buf_gc: warning "
    + "-- grant still in use by backend "
    + "domain.\n");
    + BUG();
    + }
    + gnttab_end_foreign_access_ref(
    + np->grant_tx_ref[id], GNTMAP_readonly);
    + gnttab_release_grant_reference(
    + &np->gref_tx_head, np->grant_tx_ref[id]);
    + np->grant_tx_ref[id] = GRANT_INVALID_REF;
    + add_id_to_freelist(&np->tx_skb_freelist, np->tx_skbs, id);
    + dev_kfree_skb_irq(skb);
    + }
    +
    + np->tx.rsp_cons = prod;
    +
    + /*
    + * Set a new event, then check for race with update of tx_cons.
    + * Note that it is essential to schedule a callback, no matter
    + * how few buffers are pending. Even if there is space in the
    + * transmit ring, higher layers may be blocked because too much
    + * data is outstanding: in such cases notification from Xen is
    + * likely to be the only kick that we'll get.
    + */
    + np->tx.sring->rsp_event =
    + prod + ((np->tx.sring->req_prod - prod) >> 1) + 1;
    + mb();
    + } while ((cons == prod) && (prod != np->tx.sring->rsp_prod));
    +
    + xennet_maybe_wake_tx(dev);
    +}
    +
    +static void xennet_make_frags(struct sk_buff *skb, struct net_device *dev,
    + struct xen_netif_tx_request *tx)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + char *data = skb->data;
    + unsigned long mfn;
    + RING_IDX prod = np->tx.req_prod_pvt;
    + int frags = skb_shinfo(skb)->nr_frags;
    + unsigned int offset = offset_in_page(data);
    + unsigned int len = skb_headlen(skb);
    + unsigned int id;
    + grant_ref_t ref;
    + int i;
    +
    + /* While the header overlaps a page boundary (including being
    + larger than a page), split it it into page-sized chunks. */
    + while (len > PAGE_SIZE - offset) {
    + tx->size = PAGE_SIZE - offset;
    + tx->flags |= NETTXF_more_data;
    + len -= tx->size;
    + data += tx->size;
    + offset = 0;
    +
    + id = get_id_from_freelist(&np->tx_skb_freelist, np->tx_skbs);
    + np->tx_skbs[id].skb = skb_get(skb);
    + tx = RING_GET_REQUEST(&np->tx, prod++);
    + tx->id = id;
    + ref = gnttab_claim_grant_reference(&np->gref_tx_head);
    + BUG_ON((signed short)ref < 0);
    +
    + mfn = virt_to_mfn(data);
    + gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
    + mfn, GNTMAP_readonly);
    +
    + tx->gref = np->grant_tx_ref[id] = ref;
    + tx->offset = offset;
    + tx->size = len;
    + tx->flags = 0;
    + }
    +
    + /* Grant backend access to each skb fragment page. */
    + for (i = 0; i < frags; i++) {
    + skb_frag_t *frag = skb_shinfo(skb)->frags + i;
    +
    + tx->flags |= NETTXF_more_data;
    +
    + id = get_id_from_freelist(&np->tx_skb_freelist, np->tx_skbs);
    + np->tx_skbs[id].skb = skb_get(skb);
    + tx = RING_GET_REQUEST(&np->tx, prod++);
    + tx->id = id;
    + ref = gnttab_claim_grant_reference(&np->gref_tx_head);
    + BUG_ON((signed short)ref < 0);
    +
    + mfn = pfn_to_mfn(page_to_pfn(frag->page));
    + gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
    + mfn, GNTMAP_readonly);
    +
    + tx->gref = np->grant_tx_ref[id] = ref;
    + tx->offset = frag->page_offset;
    + tx->size = frag->size;
    + tx->flags = 0;
    + }
    +
    + np->tx.req_prod_pvt = prod;
    +}
    +
    +static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
    +{
    + unsigned short id;
    + struct netfront_info *np = netdev_priv(dev);
    + struct xen_netif_tx_request *tx;
    + struct xen_netif_extra_info *extra;
    + char *data = skb->data;
    + RING_IDX i;
    + grant_ref_t ref;
    + unsigned long mfn;
    + int notify;
    + int frags = skb_shinfo(skb)->nr_frags;
    + unsigned int offset = offset_in_page(data);
    + unsigned int len = skb_headlen(skb);
    +
    + frags += (offset + len + PAGE_SIZE - 1) / PAGE_SIZE;
    + if (unlikely(frags > MAX_SKB_FRAGS + 1)) {
    + printk(KERN_ALERT "xennet: skb rides the rocket: %d frags\n",
    + frags);
    + dump_stack();
    + goto drop;
    + }
    +
    + spin_lock_irq(&np->tx_lock);
    +
    + if (unlikely(!netif_carrier_ok(dev) ||
    + (frags > 1 && !xennet_can_sg(dev)) ||
    + netif_needs_gso(dev, skb))) {
    + spin_unlock_irq(&np->tx_lock);
    + goto drop;
    + }
    +
    + i = np->tx.req_prod_pvt;
    +
    + id = get_id_from_freelist(&np->tx_skb_freelist, np->tx_skbs);
    + np->tx_skbs[id].skb = skb;
    +
    + tx = RING_GET_REQUEST(&np->tx, i);
    +
    + tx->id = id;
    + ref = gnttab_claim_grant_reference(&np->gref_tx_head);
    + BUG_ON((signed short)ref < 0);
    + mfn = virt_to_mfn(data);
    + gnttab_grant_foreign_access_ref(
    + ref, np->xbdev->otherend_id, mfn, GNTMAP_readonly);
    + tx->gref = np->grant_tx_ref[id] = ref;
    + tx->offset = offset;
    + tx->size = len;
    + extra = NULL;
    +
    + tx->flags = 0;
    + if (skb->ip_summed == CHECKSUM_PARTIAL)
    + /* local packet? */
    + tx->flags |= NETTXF_csum_blank | NETTXF_data_validated;
    + else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
    + /* remote but checksummed. */
    + tx->flags |= NETTXF_data_validated;
    +
    + if (skb_shinfo(skb)->gso_size) {
    + struct xen_netif_extra_info *gso;
    +
    + gso = (struct xen_netif_extra_info *)
    + RING_GET_REQUEST(&np->tx, ++i);
    +
    + if (extra)
    + extra->flags |= XEN_NETIF_EXTRA_FLAG_MORE;
    + else
    + tx->flags |= NETTXF_extra_info;
    +
    + gso->u.gso.size = skb_shinfo(skb)->gso_size;
    + gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
    + gso->u.gso.pad = 0;
    + gso->u.gso.features = 0;
    +
    + gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
    + gso->flags = 0;
    + extra = gso;
    + }
    +
    + np->tx.req_prod_pvt = i + 1;
    +
    + xennet_make_frags(skb, dev, tx);
    + tx->size = skb->len;
    +
    + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->tx, notify);
    + if (notify)
    + notify_remote_via_irq(np->netdev->irq);
    +
    + xennet_tx_buf_gc(dev);
    +
    + if (!netfront_tx_slot_available(np))
    + netif_stop_queue(dev);
    +
    + spin_unlock_irq(&np->tx_lock);
    +
    + np->stats.tx_bytes += skb->len;
    + np->stats.tx_packets++;
    +
    + return 0;
    +
    + drop:
    + np->stats.tx_dropped++;
    + dev_kfree_skb(skb);
    + return 0;
    +}
    +
    +static int xennet_close(struct net_device *dev)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + netif_stop_queue(np->netdev);
    + return 0;
    +}
    +
    +static struct net_device_stats *xennet_get_stats(struct net_device *dev)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + return &np->stats;
    +}
    +
    +static void xennet_move_rx_slot(struct netfront_info *np, struct sk_buff *skb,
    + grant_ref_t ref)
    +{
    + int new = xennet_rxidx(np->rx.req_prod_pvt);
    +
    + BUG_ON(np->rx_skbs[new]);
    + np->rx_skbs[new] = skb;
    + np->grant_rx_ref[new] = ref;
    + RING_GET_REQUEST(&np->rx, np->rx.req_prod_pvt)->id = new;
    + RING_GET_REQUEST(&np->rx, np->rx.req_prod_pvt)->gref = ref;
    + np->rx.req_prod_pvt++;
    +}
    +
    +static int xennet_get_extras(struct netfront_info *np,
    + struct xen_netif_extra_info *extras,
    + RING_IDX rp)
    +
    +{
    + struct xen_netif_extra_info *extra;
    + struct device *dev = &np->netdev->dev;
    + RING_IDX cons = np->rx.rsp_cons;
    + int err = 0;
    +
    + do {
    + struct sk_buff *skb;
    + grant_ref_t ref;
    +
    + if (unlikely(cons + 1 == rp)) {
    + if (net_ratelimit())
    + dev_warn(dev, "Missing extra info\n");
    + err = -EBADR;
    + break;
    + }
    +
    + extra = (struct xen_netif_extra_info *)
    + RING_GET_RESPONSE(&np->rx, ++cons);
    +
    + if (unlikely(!extra->type ||
    + extra->type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
    + if (net_ratelimit())
    + dev_warn(dev, "Invalid extra type: %d\n",
    + extra->type);
    + err = -EINVAL;
    + } else {
    + memcpy(&extras[extra->type - 1], extra,
    + sizeof(*extra));
    + }
    +
    + skb = xennet_get_rx_skb(np, cons);
    + ref = xennet_get_rx_ref(np, cons);
    + xennet_move_rx_slot(np, skb, ref);
    + } while (extra->flags & XEN_NETIF_EXTRA_FLAG_MORE);
    +
    + np->rx.rsp_cons = cons;
    + return err;
    +}
    +
    +static int xennet_get_responses(struct netfront_info *np,
    + struct netfront_rx_info *rinfo, RING_IDX rp,
    + struct sk_buff_head *list,
    + int *pages_flipped_p)
    +{
    + int pages_flipped = *pages_flipped_p;
    + struct mmu_update *mmu;
    + struct multicall_entry *mcl;
    + struct xen_netif_rx_response *rx = &rinfo->rx;
    + struct xen_netif_extra_info *extras = rinfo->extras;
    + struct device *dev = &np->netdev->dev;
    + RING_IDX cons = np->rx.rsp_cons;
    + struct sk_buff *skb = xennet_get_rx_skb(np, cons);
    + grant_ref_t ref = xennet_get_rx_ref(np, cons);
    + int max = MAX_SKB_FRAGS + (rx->status <= RX_COPY_THRESHOLD);
    + int frags = 1;
    + int err = 0;
    + unsigned long ret;
    +
    + if (rx->flags & NETRXF_extra_info) {
    + err = xennet_get_extras(np, extras, rp);
    + cons = np->rx.rsp_cons;
    + }
    +
    + for (;;) {
    + unsigned long mfn;
    +
    + if (unlikely(rx->status < 0 ||
    + rx->offset + rx->status > PAGE_SIZE)) {
    + if (net_ratelimit())
    + dev_warn(dev, "rx->offset: %x, size: %u\n",
    + rx->offset, rx->status);
    + xennet_move_rx_slot(np, skb, ref);
    + err = -EINVAL;
    + goto next;
    + }
    +
    + /*
    + * This definitely indicates a bug, either in this driver or in
    + * the backend driver. In future this should flag the bad
    + * situation to the system controller to reboot the backed.
    + */
    + if (ref == GRANT_INVALID_REF) {
    + if (net_ratelimit())
    + dev_warn(dev, "Bad rx response id %d.\n",
    + rx->id);
    + err = -EINVAL;
    + goto next;
    + }
    +
    + if (!np->copying_receiver) {
    + /* Memory pressure, insufficient buffer
    + * headroom, ... */
    + mfn = gnttab_end_foreign_transfer_ref(ref);
    + if (!mfn) {
    + if (net_ratelimit())
    + dev_warn(dev, "Unfulfilled rx req "
    + "(id=%d, st=%d).\n",
    + rx->id, rx->status);
    + xennet_move_rx_slot(np, skb, ref);
    + err = -ENOMEM;
    + goto next;
    + }
    +
    + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
    + /* Remap the page. */
    + struct page *page =
    + skb_shinfo(skb)->frags[0].page;
    + unsigned long pfn = page_to_pfn(page);
    + void *vaddr = page_address(page);
    +
    + mcl = np->rx_mcl + pages_flipped;
    + mmu = np->rx_mmu + pages_flipped;
    +
    + MULTI_update_va_mapping(mcl,
    + (unsigned long)vaddr,
    + mfn_pte(mfn, PAGE_KERNEL),
    + 0);
    + mmu->ptr = ((u64)mfn << PAGE_SHIFT)
    + | MMU_MACHPHYS_UPDATE;
    + mmu->val = pfn;
    +
    + set_phys_to_machine(pfn, mfn);
    + }
    + pages_flipped++;
    + } else {
    + ret = gnttab_end_foreign_access_ref(ref, 0);
    + BUG_ON(!ret);
    + }
    +
    + gnttab_release_grant_reference(&np->gref_rx_head, ref);
    +
    + __skb_queue_tail(list, skb);
    +
    +next:
    + if (!(rx->flags & NETRXF_more_data))
    + break;
    +
    + if (cons + frags == rp) {
    + if (net_ratelimit())
    + dev_warn(dev, "Need more frags\n");
    + err = -ENOENT;
    + break;
    + }
    +
    + rx = RING_GET_RESPONSE(&np->rx, cons + frags);
    + skb = xennet_get_rx_skb(np, cons + frags);
    + ref = xennet_get_rx_ref(np, cons + frags);
    + frags++;
    + }
    +
    + if (unlikely(frags > max)) {
    + if (net_ratelimit())
    + dev_warn(dev, "Too many frags\n");
    + err = -E2BIG;
    + }
    +
    + if (unlikely(err))
    + np->rx.rsp_cons = cons + frags;
    +
    + *pages_flipped_p = pages_flipped;
    +
    + return err;
    +}
    +
    +static int xennet_set_skb_gso(struct sk_buff *skb,
    + struct xen_netif_extra_info *gso)
    +{
    + if (!gso->u.gso.size) {
    + if (net_ratelimit())
    + printk(KERN_WARNING "GSO size must not be zero.\n");
    + return -EINVAL;
    + }
    +
    + /* Currently only TCPv4 S.O. is supported. */
    + if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
    + if (net_ratelimit())
    + printk(KERN_WARNING "Bad GSO type %d.\n", gso->u.gso.type);
    + return -EINVAL;
    + }
    +
    + skb_shinfo(skb)->gso_size = gso->u.gso.size;
    + skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
    +
    + /* Header must be checked, and gso_segs computed. */
    + skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
    + skb_shinfo(skb)->gso_segs = 0;
    +
    + return 0;
    +}
    +
    +static RING_IDX xennet_fill_frags(struct netfront_info *np,
    + struct sk_buff *skb,
    + struct sk_buff_head *list)
    +{
    + struct skb_shared_info *shinfo = skb_shinfo(skb);
    + int nr_frags = shinfo->nr_frags;
    + RING_IDX cons = np->rx.rsp_cons;
    + skb_frag_t *frag = shinfo->frags + nr_frags;
    + struct sk_buff *nskb;
    +
    + while ((nskb = __skb_dequeue(list))) {
    + struct xen_netif_rx_response *rx =
    + RING_GET_RESPONSE(&np->rx, ++cons);
    +
    + frag->page = skb_shinfo(nskb)->frags[0].page;
    + frag->page_offset = rx->offset;
    + frag->size = rx->status;
    +
    + skb->data_len += rx->status;
    +
    + skb_shinfo(nskb)->nr_frags = 0;
    + kfree_skb(nskb);
    +
    + frag++;
    + nr_frags++;
    + }
    +
    + shinfo->nr_frags = nr_frags;
    + return cons;
    +}
    +
    +static int skb_checksum_setup(struct sk_buff *skb)
    +{
    + struct iphdr *iph;
    + unsigned char *th;
    + int err = -EPROTO;
    +
    + if (skb->protocol != htons(ETH_P_IP))
    + goto out;
    +
    + iph = (void *)skb->data;
    + th = skb->data + 4 * iph->ihl;
    + if (th >= skb_tail_pointer(skb))
    + goto out;
    +
    + skb->csum_start = th - skb->head;
    + switch (iph->protocol) {
    + case IPPROTO_TCP:
    + skb->csum_offset = offsetof(struct tcphdr, check);
    + break;
    + case IPPROTO_UDP:
    + skb->csum_offset = offsetof(struct udphdr, check);
    + break;
    + default:
    + if (net_ratelimit())
    + printk(KERN_ERR "Attempting to checksum a non-"
    + "TCP/UDP packet, dropping a protocol"
    + " %d packet", iph->protocol);
    + goto out;
    + }
    +
    + if ((th + skb->csum_offset + 2) > skb_tail_pointer(skb))
    + goto out;
    +
    + err = 0;
    +
    +out:
    + return err;
    +}
    +
    +static int handle_incoming_queue(struct net_device *dev,
    + struct sk_buff_head *rxq)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + int packets_dropped = 0;
    + struct sk_buff *skb;
    +
    + while ((skb = __skb_dequeue(rxq)) != NULL) {
    + struct page *page = NETFRONT_SKB_CB(skb)->page;
    + void *vaddr = page_address(page);
    + unsigned offset = NETFRONT_SKB_CB(skb)->offset;
    +
    + memcpy(skb->data, vaddr + offset,
    + skb_headlen(skb));
    +
    + if (page != skb_shinfo(skb)->frags[0].page)
    + __free_page(page);
    +
    + /* Ethernet work: Delayed to here as it peeks the header. */
    + skb->protocol = eth_type_trans(skb, dev);
    +
    + if (skb->ip_summed == CHECKSUM_PARTIAL) {
    + if (skb_checksum_setup(skb)) {
    + kfree_skb(skb);
    + packets_dropped++;
    + np->stats.rx_errors++;
    + continue;
    + }
    + }
    +
    + np->stats.rx_packets++;
    + np->stats.rx_bytes += skb->len;
    +
    + /* Pass it up. */
    + netif_receive_skb(skb);
    + dev->last_rx = jiffies;
    + }
    +
    + return packets_dropped;
    +}
    +
    +static int xennet_poll(struct net_device *dev, int *pbudget)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + struct sk_buff *skb;
    + struct netfront_rx_info rinfo;
    + struct xen_netif_rx_response *rx = &rinfo.rx;
    + struct xen_netif_extra_info *extras = rinfo.extras;
    + RING_IDX i, rp;
    + struct multicall_entry *mcl;
    + int work_done, budget, more_to_do = 1;
    + struct sk_buff_head rxq;
    + struct sk_buff_head errq;
    + struct sk_buff_head tmpq;
    + unsigned long flags;
    + unsigned int len;
    + int pages_flipped = 0;
    + int err;
    +
    + spin_lock(&np->rx_lock);
    +
    + if (unlikely(!netif_carrier_ok(dev))) {
    + spin_unlock(&np->rx_lock);
    + return 0;
    + }
    +
    + skb_queue_head_init(&rxq);
    + skb_queue_head_init(&errq);
    + skb_queue_head_init(&tmpq);
    +
    + if ((budget = *pbudget) > dev->quota)
    + budget = dev->quota;
    + rp = np->rx.sring->rsp_prod;
    + rmb(); /* Ensure we see queued responses up to 'rp'. */
    +
    + i = np->rx.rsp_cons;
    + work_done = 0;
    + while ((i != rp) && (work_done < budget)) {
    + memcpy(rx, RING_GET_RESPONSE(&np->rx, i), sizeof(*rx));
    + memset(extras, 0, sizeof(rinfo.extras));
    +
    + err = xennet_get_responses(np, &rinfo, rp, &tmpq,
    + &pages_flipped);
    +
    + if (unlikely(err)) {
    +err:
    + while ((skb = __skb_dequeue(&tmpq)))
    + __skb_queue_tail(&errq, skb);
    + np->stats.rx_errors++;
    + i = np->rx.rsp_cons;
    + continue;
    + }
    +
    + skb = __skb_dequeue(&tmpq);
    +
    + if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
    + struct xen_netif_extra_info *gso;
    + gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
    +
    + if (unlikely(xennet_set_skb_gso(skb, gso))) {
    + __skb_queue_head(&tmpq, skb);
    + np->rx.rsp_cons += skb_queue_len(&tmpq);
    + goto err;
    + }
    + }
    +
    + NETFRONT_SKB_CB(skb)->page = skb_shinfo(skb)->frags[0].page;
    + NETFRONT_SKB_CB(skb)->offset = rx->offset;
    +
    + len = rx->status;
    + if (len > RX_COPY_THRESHOLD)
    + len = RX_COPY_THRESHOLD;
    + skb_put(skb, len);
    +
    + if (rx->status > len) {
    + skb_shinfo(skb)->frags[0].page_offset =
    + rx->offset + len;
    + skb_shinfo(skb)->frags[0].size = rx->status - len;
    + skb->data_len = rx->status - len;
    + } else {
    + skb_shinfo(skb)->frags[0].page = NULL;
    + skb_shinfo(skb)->nr_frags = 0;
    + }
    +
    + i = xennet_fill_frags(np, skb, &tmpq);
    +
    + /*
    + * Truesize approximates the size of true data plus
    + * any supervisor overheads. Adding hypervisor
    + * overheads has been shown to significantly reduce
    + * achievable bandwidth with the default receive
    + * buffer size. It is therefore not wise to account
    + * for it here.
    + *
    + * After alloc_skb(RX_COPY_THRESHOLD), truesize is set
    + * to RX_COPY_THRESHOLD + the supervisor
    + * overheads. Here, we add the size of the data pulled
    + * in xennet_fill_frags().
    + *
    + * We also adjust for any unused space in the main
    + * data area by subtracting (RX_COPY_THRESHOLD -
    + * len). This is especially important with drivers
    + * which split incoming packets into header and data,
    + * using only 66 bytes of the main data area (see the
    + * e1000 driver for example.) On such systems,
    + * without this last adjustement, our achievable
    + * receive throughout using the standard receive
    + * buffer size was cut by 25%(!!!).
    + */
    + skb->truesize += skb->data_len - (RX_COPY_THRESHOLD - len);
    + skb->len += skb->data_len;
    +
    + if (rx->flags & NETRXF_csum_blank)
    + skb->ip_summed = CHECKSUM_PARTIAL;
    + else if (rx->flags & NETRXF_data_validated)
    + skb->ip_summed = CHECKSUM_UNNECESSARY;
    +
    + __skb_queue_tail(&rxq, skb);
    +
    + np->rx.rsp_cons = ++i;
    + work_done++;
    + }
    +
    + if (pages_flipped) {
    + /* Do all the remapping work, and M2P updates. */
    + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
    + mcl = np->rx_mcl + pages_flipped;
    + MULTI_mmu_update(mcl, np->rx_mmu,
    + pages_flipped, 0, DOMID_SELF);
    + (void)HYPERVISOR_multicall(np->rx_mcl,
    + pages_flipped + 1);
    + }
    + }
    +
    + while ((skb = __skb_dequeue(&errq)))
    + kfree_skb(skb);
    +
    + work_done -= handle_incoming_queue(dev, &rxq);
    +
    + /* If we get a callback with very few responses, reduce fill target. */
    + /* NB. Note exponential increase, linear decrease. */
    + if (((np->rx.req_prod_pvt - np->rx.sring->rsp_prod) >
    + ((3*np->rx_target) / 4)) &&
    + (--np->rx_target < np->rx_min_target))
    + np->rx_target = np->rx_min_target;
    +
    + xennet_alloc_rx_buffers(dev);
    +
    + *pbudget -= work_done;
    + dev->quota -= work_done;
    +
    + if (work_done < budget) {
    + local_irq_save(flags);
    +
    + RING_FINAL_CHECK_FOR_RESPONSES(&np->rx, more_to_do);
    + if (!more_to_do)
    + __netif_rx_complete(dev);
    +
    + local_irq_restore(flags);
    + }
    +
    + spin_unlock(&np->rx_lock);
    +
    + return more_to_do;
    +}
    +
    +static int xennet_change_mtu(struct net_device *dev, int mtu)
    +{
    + int max = xennet_can_sg(dev) ? 65535 - ETH_HLEN : ETH_DATA_LEN;
    +
    + if (mtu > max)
    + return -EINVAL;
    + dev->mtu = mtu;
    + return 0;
    +}
    +
    +static void xennet_release_tx_bufs(struct netfront_info *np)
    +{
    + struct sk_buff *skb;
    + int i;
    +
    + for (i = 0; i < NET_TX_RING_SIZE; i++) {
    + /* Skip over entries which are actually freelist references */
    + if ((unsigned long)np->tx_skbs[i].skb < PAGE_OFFSET)
    + continue;
    +
    + skb = np->tx_skbs[i].skb;
    + gnttab_end_foreign_access_ref(np->grant_tx_ref[i],
    + GNTMAP_readonly);
    + gnttab_release_grant_reference(&np->gref_tx_head,
    + np->grant_tx_ref[i]);
    + np->grant_tx_ref[i] = GRANT_INVALID_REF;
    + add_id_to_freelist(&np->tx_skb_freelist, np->tx_skbs, i);
    + dev_kfree_skb_irq(skb);
    + }
    +}
    +
    +static void xennet_release_rx_bufs(struct netfront_info *np)
    +{
    + struct mmu_update *mmu = np->rx_mmu;
    + struct multicall_entry *mcl = np->rx_mcl;
    + struct sk_buff_head free_list;
    + struct sk_buff *skb;
    + unsigned long mfn;
    + int xfer = 0, noxfer = 0, unused = 0;
    + int id, ref;
    +
    + if (np->copying_receiver) {
    + dev_warn(&np->netdev->dev, "%s: fix me for copying receiver.\n",
    + __func__);
    + return;
    + }
    +
    + skb_queue_head_init(&free_list);
    +
    + spin_lock_bh(&np->rx_lock);
    +
    + for (id = 0; id < NET_RX_RING_SIZE; id++) {
    + if ((ref = np->grant_rx_ref[id]) == GRANT_INVALID_REF) {
    + unused++;
    + continue;
    + }
    +
    + skb = np->rx_skbs[id];
    + mfn = gnttab_end_foreign_transfer_ref(ref);
    + gnttab_release_grant_reference(&np->gref_rx_head, ref);
    + np->grant_rx_ref[id] = GRANT_INVALID_REF;
    +
    + if (0 == mfn) {
    + skb_shinfo(skb)->nr_frags = 0;
    + dev_kfree_skb(skb);
    + noxfer++;
    + continue;
    + }
    +
    + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
    + /* Remap the page. */
    + struct page *page = skb_shinfo(skb)->frags[0].page;
    + unsigned long pfn = page_to_pfn(page);
    + void *vaddr = page_address(page);
    +
    + MULTI_update_va_mapping(mcl, (unsigned long)vaddr,
    + mfn_pte(mfn, PAGE_KERNEL),
    + 0);
    + mcl++;
    + mmu->ptr = ((u64)mfn << PAGE_SHIFT)
    + | MMU_MACHPHYS_UPDATE;
    + mmu->val = pfn;
    + mmu++;
    +
    + set_phys_to_machine(pfn, mfn);
    + }
    + __skb_queue_tail(&free_list, skb);
    + xfer++;
    + }
    +
    + dev_info(&np->netdev->dev, "%s: %d xfer, %d noxfer, %d unused\n",
    + __func__, xfer, noxfer, unused);
    +
    + if (xfer) {
    + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
    + /* Do all the remapping work and M2P updates. */
    + MULTI_mmu_update(mcl, np->rx_mmu, mmu - np->rx_mmu,
    + 0, DOMID_SELF);
    + mcl++;
    + HYPERVISOR_multicall(np->rx_mcl, mcl - np->rx_mcl);
    + }
    + }
    +
    + while ((skb = __skb_dequeue(&free_list)) != NULL)
    + dev_kfree_skb(skb);
    +
    + spin_unlock_bh(&np->rx_lock);
    +}
    +
    +static void xennet_uninit(struct net_device *dev)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + xennet_release_tx_bufs(np);
    + xennet_release_rx_bufs(np);
    + gnttab_free_grant_references(np->gref_tx_head);
    + gnttab_free_grant_references(np->gref_rx_head);
    +}
    +
    +static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev)
    +{
    + int i, err;
    + struct net_device *netdev;
    + struct netfront_info *np;
    +
    + netdev = alloc_etherdev(sizeof(struct netfront_info));
    + if (!netdev) {
    + printk(KERN_WARNING "%s> alloc_etherdev failed.\n",
    + __func__);
    + return ERR_PTR(-ENOMEM);
    + }
    +
    + np = netdev_priv(netdev);
    + np->xbdev = dev;
    +
    + spin_lock_init(&np->tx_lock);
    + spin_lock_init(&np->rx_lock);
    +
    + skb_queue_head_init(&np->rx_batch);
    + np->rx_target = RX_DFL_MIN_TARGET;
    + np->rx_min_target = RX_DFL_MIN_TARGET;
    + np->rx_max_target = RX_MAX_TARGET;
    +
    + init_timer(&np->rx_refill_timer);
    + np->rx_refill_timer.data = (unsigned long)netdev;
    + np->rx_refill_timer.function = rx_refill_timeout;
    +
    + /* Initialise tx_skbs as a free chain containing every entry. */
    + np->tx_skb_freelist = 0;
    + for (i = 0; i < NET_TX_RING_SIZE; i++) {
    + np->tx_skbs[i].link = i+1;
    + np->grant_tx_ref[i] = GRANT_INVALID_REF;
    + }
    +
    + /* Clear out rx_skbs */
    + for (i = 0; i < NET_RX_RING_SIZE; i++) {
    + np->rx_skbs[i] = NULL;
    + np->grant_rx_ref[i] = GRANT_INVALID_REF;
    + }
    +
    + /* A grant for every tx ring slot */
    + if (gnttab_alloc_grant_references(TX_MAX_TARGET,
    + &np->gref_tx_head) < 0) {
    + printk(KERN_ALERT "#### netfront can't alloc tx grant refs\n");
    + err = -ENOMEM;
    + goto exit;
    + }
    + /* A grant for every rx ring slot */
    + if (gnttab_alloc_grant_references(RX_MAX_TARGET,
    + &np->gref_rx_head) < 0) {
    + printk(KERN_ALERT "#### netfront can't alloc rx grant refs\n");
    + err = -ENOMEM;
    + goto exit_free_tx;
    + }
    +
    + netdev->open = xennet_open;
    + netdev->hard_start_xmit = xennet_start_xmit;
    + netdev->stop = xennet_close;
    + netdev->get_stats = xennet_get_stats;
    + netdev->poll = xennet_poll;
    + netdev->uninit = xennet_uninit;
    + netdev->change_mtu = xennet_change_mtu;
    + netdev->weight = 64;
    + netdev->features = NETIF_F_IP_CSUM;
    +
    + SET_ETHTOOL_OPS(netdev, &xennet_ethtool_ops);
    + SET_MODULE_OWNER(netdev);
    + SET_NETDEV_DEV(netdev, &dev->dev);
    +
    + np->netdev = netdev;
    +
    + netif_carrier_off(netdev);
    +
    + return netdev;
    +
    + exit_free_tx:
    + gnttab_free_grant_references(np->gref_tx_head);
    + exit:
    + free_netdev(netdev);
    + return ERR_PTR(err);
    +}
    +
    +/**
    + * Entry point to this code when a new device is created. Allocate the basic
    + * structures and the ring buffers for communication with the backend, and
    + * inform the backend of the appropriate details for those.
    + */
    +static int __devinit netfront_probe(struct xenbus_device *dev,
    + const struct xenbus_device_id *id)
    +{
    + int err;
    + struct net_device *netdev;
    + struct netfront_info *info;
    +
    + netdev = xennet_create_dev(dev);
    + if (IS_ERR(netdev)) {
    + err = PTR_ERR(netdev);
    + xenbus_dev_fatal(dev, err, "creating netdev");
    + return err;
    + }
    +
    + info = netdev_priv(netdev);
    + dev->dev.driver_data = info;
    +
    + err = register_netdev(info->netdev);
    + if (err) {
    + printk(KERN_WARNING "%s: register_netdev err=%d\n",
    + __func__, err);
    + goto fail;
    + }
    +
    + err = xennet_sysfs_addif(info->netdev);
    + if (err) {
    + unregister_netdev(info->netdev);
    + printk(KERN_WARNING "%s: add sysfs failed err=%d\n",
    + __func__, err);
    + goto fail;
    + }
    +
    + return 0;
    +
    + fail:
    + free_netdev(netdev);
    + dev->dev.driver_data = NULL;
    + return err;
    +}
    +
    +static void xennet_end_access(int ref, void *page)
    +{
    + /* This frees the page as a side-effect */
    + if (ref != GRANT_INVALID_REF)
    + gnttab_end_foreign_access(ref, 0, (unsigned long)page);
    +}
    +
    +static void xennet_disconnect_backend(struct netfront_info *info)
    +{
    + /* Stop old i/f to prevent errors whilst we rebuild the state. */
    + spin_lock_bh(&info->rx_lock);
    + spin_lock_irq(&info->tx_lock);
    + netif_carrier_off(info->netdev);
    + spin_unlock_irq(&info->tx_lock);
    + spin_unlock_bh(&info->rx_lock);
    +
    + if (info->netdev->irq)
    + unbind_from_irqhandler(info->netdev->irq, info->netdev);
    + info->evtchn = info->netdev->irq = 0;
    +
    + /* End access and free the pages */
    + xennet_end_access(info->tx_ring_ref, info->tx.sring);
    + xennet_end_access(info->rx_ring_ref, info->rx.sring);
    +
    + info->tx_ring_ref = GRANT_INVALID_REF;
    + info->rx_ring_ref = GRANT_INVALID_REF;
    + info->tx.sring = NULL;
    + info->rx.sring = NULL;
    +}
    +
    +/**
    + * We are reconnecting to the backend, due to a suspend/resume, or a backend
    + * driver restart. We tear down our netif structure and recreate it, but
    + * leave the device-layer structures intact so that this is transparent to the
    + * rest of the kernel.
    + */
    +static int netfront_resume(struct xenbus_device *dev)
    +{
    + struct netfront_info *info = dev->dev.driver_data;
    +
    + dev_dbg(&dev->dev, "%s\n", dev->nodename);
    +
    + xennet_disconnect_backend(info);
    + return 0;
    +}
    +
    +static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
    +{
    + char *s, *e, *macstr;
    + int i;
    +
    + macstr = s = xenbus_read(XBT_NIL, dev->nodename, "mac", NULL);
    + if (IS_ERR(macstr))
    + return PTR_ERR(macstr);
    +
    + for (i = 0; i < ETH_ALEN; i++) {
    + mac[i] = simple_strtoul(s, &e, 16);
    + if ((s == e) || (*e != ((i == ETH_ALEN-1) ? '\0' : ':'))) {
    + kfree(macstr);
    + return -ENOENT;
    + }
    + s = e+1;
    + }
    +
    + kfree(macstr);
    + return 0;
    +}
    +
    +static irqreturn_t xennet_interrupt(int irq, void *dev_id)
    +{
    + struct net_device *dev = dev_id;
    + struct netfront_info *np = netdev_priv(dev);
    + unsigned long flags;
    +
    + spin_lock_irqsave(&np->tx_lock, flags);
    +
    + if (likely(netif_carrier_ok(dev))) {
    + xennet_tx_buf_gc(dev);
    + /* Under tx_lock: protects access to rx shared-ring indexes. */
    + if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
    + netif_rx_schedule(dev);
    + }
    +
    + spin_unlock_irqrestore(&np->tx_lock, flags);
    +
    + return IRQ_HANDLED;
    +}
    +
    +static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
    +{
    + struct xen_netif_tx_sring *txs;
    + struct xen_netif_rx_sring *rxs;
    + int err;
    + struct net_device *netdev = info->netdev;
    +
    + info->tx_ring_ref = GRANT_INVALID_REF;
    + info->rx_ring_ref = GRANT_INVALID_REF;
    + info->rx.sring = NULL;
    + info->tx.sring = NULL;
    + netdev->irq = 0;
    +
    + err = xen_net_read_mac(dev, netdev->dev_addr);
    + if (err) {
    + xenbus_dev_fatal(dev, err, "parsing %s/mac", dev->nodename);
    + goto fail;
    + }
    +
    + txs = (struct xen_netif_tx_sring *)get_zeroed_page(GFP_KERNEL);
    + if (!txs) {
    + err = -ENOMEM;
    + xenbus_dev_fatal(dev, err, "allocating tx ring page");
    + goto fail;
    + }
    + SHARED_RING_INIT(txs);
    + FRONT_RING_INIT(&info->tx, txs, PAGE_SIZE);
    +
    + err = xenbus_grant_ring(dev, virt_to_mfn(txs));
    + if (err < 0) {
    + free_page((unsigned long)txs);
    + goto fail;
    + }
    +
    + info->tx_ring_ref = err;
    + rxs = (struct xen_netif_rx_sring *)get_zeroed_page(GFP_KERNEL);
    + if (!rxs) {
    + err = -ENOMEM;
    + xenbus_dev_fatal(dev, err, "allocating rx ring page");
    + goto fail;
    + }
    + SHARED_RING_INIT(rxs);
    + FRONT_RING_INIT(&info->rx, rxs, PAGE_SIZE);
    +
    + err = xenbus_grant_ring(dev, virt_to_mfn(rxs));
    + if (err < 0) {
    + free_page((unsigned long)rxs);
    + goto fail;
    + }
    + info->rx_ring_ref = err;
    +
    + err = xenbus_alloc_evtchn(dev, &info->evtchn);
    + if (err)
    + goto fail;
    +
    + err = bind_evtchn_to_irqhandler(info->evtchn, xennet_interrupt,
    + IRQF_SAMPLE_RANDOM, netdev->name,
    + netdev);
    + if (err < 0)
    + goto fail;
    + netdev->irq = err;
    + return 0;
    +
    + fail:
    + return err;
    +}
    +
    +/* Common code used when first setting up, and when resuming. */
    +static int talk_to_backend(struct xenbus_device *dev,
    + struct netfront_info *info)
    +{
    + const char *message;
    + struct xenbus_transaction xbt;
    + int err;
    +
    + /* Create shared ring, alloc event channel. */
    + err = setup_netfront(dev, info);
    + if (err)
    + goto out;
    +
    +again:
    + err = xenbus_transaction_start(&xbt);
    + if (err) {
    + xenbus_dev_fatal(dev, err, "starting transaction");
    + goto destroy_ring;
    + }
    +
    + err = xenbus_printf(xbt, dev->nodename, "tx-ring-ref","%u",
    + info->tx_ring_ref);
    + if (err) {
    + message = "writing tx ring-ref";
    + goto abort_transaction;
    + }
    + err = xenbus_printf(xbt, dev->nodename, "rx-ring-ref","%u",
    + info->rx_ring_ref);
    + if (err) {
    + message = "writing rx ring-ref";
    + goto abort_transaction;
    + }
    + err = xenbus_printf(xbt, dev->nodename,
    + "event-channel", "%u", info->evtchn);
    + if (err) {
    + message = "writing event-channel";
    + goto abort_transaction;
    + }
    +
    + err = xenbus_printf(xbt, dev->nodename, "request-rx-copy", "%u",
    + info->copying_receiver);
    + if (err) {
    + message = "writing request-rx-copy";
    + goto abort_transaction;
    + }
    +
    + err = xenbus_printf(xbt, dev->nodename, "feature-rx-notify", "%d", 1);
    + if (err) {
    + message = "writing feature-rx-notify";
    + goto abort_transaction;
    + }
    +
    + err = xenbus_printf(xbt, dev->nodename, "feature-sg", "%d", 1);
    + if (err) {
    + message = "writing feature-sg";
    + goto abort_transaction;
    + }
    +
    + err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv4", "%d", 1);
    + if (err) {
    + message = "writing feature-gso-tcpv4";
    + goto abort_transaction;
    + }
    +
    + err = xenbus_transaction_end(xbt, 0);
    + if (err) {
    + if (err == -EAGAIN)
    + goto again;
    + xenbus_dev_fatal(dev, err, "completing transaction");
    + goto destroy_ring;
    + }
    +
    + return 0;
    +
    + abort_transaction:
    + xenbus_transaction_end(xbt, 1);
    + xenbus_dev_fatal(dev, err, "%s", message);
    + destroy_ring:
    + xennet_disconnect_backend(info);
    + out:
    + return err;
    +}
    +
    +static int xennet_set_sg(struct net_device *dev, u32 data)
    +{
    + if (data) {
    + struct netfront_info *np = netdev_priv(dev);
    + int val;
    +
    + if (xenbus_scanf(XBT_NIL, np->xbdev->otherend, "feature-sg",
    + "%d", &val) < 0)
    + val = 0;
    + if (!val)
    + return -ENOSYS;
    + } else if (dev->mtu > ETH_DATA_LEN)
    + dev->mtu = ETH_DATA_LEN;
    +
    + return ethtool_op_set_sg(dev, data);
    +}
    +
    +static int xennet_set_tso(struct net_device *dev, u32 data)
    +{
    + if (data) {
    + struct netfront_info *np = netdev_priv(dev);
    + int val;
    +
    + if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
    + "feature-gso-tcpv4", "%d", &val) < 0)
    + val = 0;
    + if (!val)
    + return -ENOSYS;
    + }
    +
    + return ethtool_op_set_tso(dev, data);
    +}
    +
    +static void xennet_set_features(struct net_device *dev)
    +{
    + /* Turn off all GSO bits except ROBUST. */
    + dev->features &= (1 << NETIF_F_GSO_SHIFT) - 1;
    + dev->features |= NETIF_F_GSO_ROBUST;
    + xennet_set_sg(dev, 0);
    +
    + /* We need checksum offload to enable scatter/gather and TSO. */
    + if (!(dev->features & NETIF_F_IP_CSUM))
    + return;
    +
    + if (!xennet_set_sg(dev, 1))
    + xennet_set_tso(dev, 1);
    +}
    +
    +static int xennet_connect(struct net_device *dev)
    +{
    + struct netfront_info *np = netdev_priv(dev);
    + int i, requeue_idx, err;
    + struct sk_buff *skb;
    + grant_ref_t ref;
    + struct xen_netif_rx_request *req;
    + unsigned int feature_rx_copy, feature_rx_flip;
    +
    + err = xenbus_scanf(XBT_NIL, np->xbdev->otherend,
    + "feature-rx-copy", "%u", &feature_rx_copy);
    + if (err != 1)
    + feature_rx_copy = 0;
    +
    + err = xenbus_scanf(XBT_NIL, np->xbdev->otherend,
    + "feature-rx-flip", "%u", &feature_rx_flip);
    + /* Flip is the default, since it was once the only mode of
    + operation. */
    + if (err != 1)
    + feature_rx_flip = 1;
    +
    + /*
    + * Copy packets on receive path if:
    + * (a) This was requested by user, and the backend supports it; or
    + * (b) Flipping was requested, but this is unsupported by the backend.
    + */
    + np->copying_receiver = (((rx_mode == RX_COPY) && feature_rx_copy) ||
    + ((rx_mode == RX_FLIP) && !feature_rx_flip));
    +
    + err = talk_to_backend(np->xbdev, np);
    + if (err)
    + return err;
    +
    + xennet_set_features(dev);
    +
    + dev_info(&dev->dev, "has %s receive path.\n",
    + np->copying_receiver ? "copying" : "flipping");
    +
    + spin_lock_bh(&np->rx_lock);
    + spin_lock_irq(&np->tx_lock);
    +
    + /* Step 1: Discard all pending TX packet fragments. */
    + xennet_release_tx_bufs(np);
    +
    + /* Step 2: Rebuild the RX buffer freelist and the RX ring itself. */
    + for (requeue_idx = 0, i = 0; i < NET_RX_RING_SIZE; i++) {
    + if (!np->rx_skbs[i])
    + continue;
    +
    + skb = np->rx_skbs[requeue_idx] = xennet_get_rx_skb(np, i);
    + ref = np->grant_rx_ref[requeue_idx] = xennet_get_rx_ref(np, i);
    + req = RING_GET_REQUEST(&np->rx, requeue_idx);
    +
    + if (!np->copying_receiver) {
    + gnttab_grant_foreign_transfer_ref(
    + ref, np->xbdev->otherend_id,
    + page_to_pfn(skb_shinfo(skb)->frags->page));
    + } else {
    + gnttab_grant_foreign_access_ref(
    + ref, np->xbdev->otherend_id,
    + pfn_to_mfn(page_to_pfn(skb_shinfo(skb)->
    + frags->page)),
    + 0);
    + }
    + req->gref = ref;
    + req->id = requeue_idx;
    +
    + requeue_idx++;
    + }
    +
    + np->rx.req_prod_pvt = requeue_idx;
    +
    + /*
    + * Step 3: All public and private state should now be sane. Get
    + * ready to start sending and receiving packets and give the driver
    + * domain a kick because we've probably just requeued some
    + * packets.
    + */
    + netif_carrier_on(np->netdev);
    + notify_remote_via_irq(np->netdev->irq);
    + xennet_tx_buf_gc(dev);
    + xennet_alloc_rx_buffers(dev);
    +
    + spin_unlock_irq(&np->tx_lock);
    + spin_unlock_bh(&np->rx_lock);
    +
    + return 0;
    +}
    +
    +/**
    + * Callback received when the backend's state changes.
    + */
    +static void backend_changed(struct xenbus_device *dev,
    + enum xenbus_state backend_state)
    +{
    + struct netfront_info *np = dev->dev.driver_data;
    + struct net_device *netdev = np->netdev;
    +
    + dev_dbg(&dev->dev, "%s\n", xenbus_strstate(backend_state));
    +
    + switch (backend_state) {
    + case XenbusStateInitialising:
    + case XenbusStateInitialised:
    + case XenbusStateConnected:
    + case XenbusStateUnknown:
    + case XenbusStateClosed:
    + break;
    +
    + case XenbusStateInitWait:
    + if (dev->state != XenbusStateInitialising)
    + break;
    + if (xennet_connect(netdev) != 0)
    + break;
    + xenbus_switch_state(dev, XenbusStateConnected);
    + break;
    +
    + case XenbusStateClosing:
    + xenbus_frontend_closed(dev);
    + break;
    + }
    +}
    +
    +static struct ethtool_ops xennet_ethtool_ops =
    +{
    + .get_tx_csum = ethtool_op_get_tx_csum,
    + .set_tx_csum = ethtool_op_set_tx_csum,
    + .get_sg = ethtool_op_get_sg,
    + .set_sg = xennet_set_sg,
    + .get_tso = ethtool_op_get_tso,
    + .set_tso = xennet_set_tso,
    + .get_link = ethtool_op_get_link,
    +};
    +
    +#ifdef CONFIG_SYSFS
    +static ssize_t show_rxbuf_min(struct device *dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct net_device *netdev = to_net_dev(dev);
    + struct netfront_info *info = netdev_priv(netdev);
    +
    + return sprintf(buf, "%u\n", info->rx_min_target);
    +}
    +
    +static ssize_t store_rxbuf_min(struct device *dev,
    + struct device_attribute *attr,
    + const char *buf, size_t len)
    +{
    + struct net_device *netdev = to_net_dev(dev);
    + struct netfront_info *np = netdev_priv(netdev);
    + char *endp;
    + unsigned long target;
    +
    + if (!capable(CAP_NET_ADMIN))
    + return -EPERM;
    +
    + target = simple_strtoul(buf, &endp, 0);
    + if (endp == buf)
    + return -EBADMSG;
    +
    + if (target < RX_MIN_TARGET)
    + target = RX_MIN_TARGET;
    + if (target > RX_MAX_TARGET)
    + target = RX_MAX_TARGET;
    +
    + spin_lock_bh(&np->rx_lock);
    + if (target > np->rx_max_target)
    + np->rx_max_target = target;
    + np->rx_min_target = target;
    + if (target > np->rx_target)
    + np->rx_target = target;
    +
    + xennet_alloc_rx_buffers(netdev);
    +
    + spin_unlock_bh(&np->rx_lock);
    + return len;
    +}
    +
    +static ssize_t show_rxbuf_max(struct device *dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct net_device *netdev = to_net_dev(dev);
    + struct netfront_info *info = netdev_priv(netdev);
    +
    + return sprintf(buf, "%u\n", info->rx_max_target);
    +}
    +
    +static ssize_t store_rxbuf_max(struct device *dev,
    + struct device_attribute *attr,
    + const char *buf, size_t len)
    +{
    + struct net_device *netdev = to_net_dev(dev);
    + struct netfront_info *np = netdev_priv(netdev);
    + char *endp;
    + unsigned long target;
    +
    + if (!capable(CAP_NET_ADMIN))
    + return -EPERM;
    +
    + target = simple_strtoul(buf, &endp, 0);
    + if (endp == buf)
    + return -EBADMSG;
    +
    + if (target < RX_MIN_TARGET)
    + target = RX_MIN_TARGET;
    + if (target > RX_MAX_TARGET)
    + target = RX_MAX_TARGET;
    +
    + spin_lock_bh(&np->rx_lock);
    + if (target < np->rx_min_target)
    + np->rx_min_target = target;
    + np->rx_max_target = target;
    + if (target < np->rx_target)
    + np->rx_target = target;
    +
    + xennet_alloc_rx_buffers(netdev);
    +
    + spin_unlock_bh(&np->rx_lock);
    + return len;
    +}
    +
    +static ssize_t show_rxbuf_cur(struct device *dev,
    + struct device_attribute *attr, char *buf)
    +{
    + struct net_device *netdev = to_net_dev(dev);
    + struct netfront_info *info = netdev_priv(netdev);
    +
    + return sprintf(buf, "%u\n", info->rx_target);
    +}
    +
    +static struct device_attribute xennet_attrs[] = {
    + __ATTR(rxbuf_min, S_IRUGO|S_IWUSR, show_rxbuf_min, store_rxbuf_min),
    + __ATTR(rxbuf_max, S_IRUGO|S_IWUSR, show_rxbuf_max, store_rxbuf_max),
    + __ATTR(rxbuf_cur, S_IRUGO, show_rxbuf_cur, NULL),
    +};
    +
    +static int xennet_sysfs_addif(struct net_device *netdev)
    +{
    + int i;
    + int err;
    +
    + for (i = 0; i < ARRAY_SIZE(xennet_attrs); i++) {
    + err = device_create_file(&netdev->dev,
    + &xennet_attrs[i]);
    + if (err)
    + goto fail;
    + }
    + return 0;
    +
    + fail:
    + while (--i >= 0)
    + device_remove_file(&netdev->dev, &xennet_attrs[i]);
    + return err;
    +}
    +
    +static void xennet_sysfs_delif(struct net_device *netdev)
    +{
    + int i;
    +
    + for (i = 0; i < ARRAY_SIZE(xennet_attrs); i++)
    + device_remove_file(&netdev->dev, &xennet_attrs[i]);
    +}
    +
    +#endif /* CONFIG_SYSFS */
    +
    +static struct xenbus_device_id netfront_ids[] = {
    + { "vif" },
    + { "" }
    +};
    +
    +
    +static int __devexit xennet_remove(struct xenbus_device *dev)
    +{
    + struct netfront_info *info = dev->dev.driver_data;
    +
    + dev_dbg(&dev->dev, "%s\n", dev->nodename);
    +
    + unregister_netdev(info->netdev);
    +
    + xennet_disconnect_backend(info);
    +
    + del_timer_sync(&info->rx_refill_timer);
    +
    + xennet_sysfs_delif(info->netdev);
    +
    + free_netdev(info->netdev);
    +
    + return 0;
    +}
    +
    +static struct xenbus_driver netfront = {
    + .name = "vif",
    + .owner = THIS_MODULE,
    + .ids = netfront_ids,
    + .probe = netfront_probe,
    + .remove = __devexit_p(xennet_remove),
    + .resume = netfront_resume,
    + .otherend_changed = backend_changed,
    +};
    +
    +static int __init netif_init(void)
    +{
    + if (!is_running_on_xen())
    + return -ENODEV;
    +
    + if (is_initial_xendomain())
    + return 0;
    +
    + printk(KERN_INFO "Initialising Xen virtual ethernet driver.\n");
    +
    + return xenbus_register_frontend(&netfront);
    +}
    +module_init(netif_init);
    +
    +
    +static void __exit netif_exit(void)
    +{
    + if (is_initial_xendomain())
    + return;
    +
    + return xenbus_unregister_driver(&netfront);
    +}
    +module_exit(netif_exit);
    +
    +MODULE_DESCRIPTION("Xen virtual network device frontend");
    +MODULE_LICENSE("GPL");
    --

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