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SubjectRe: [PATCH 5/8] lguest: the net driver
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A simple net driver for lguest.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
drivers/net/Makefile | 1
drivers/net/lguest_net.c | 355 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 356 insertions(+)
===================================================================
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -220,3 +220,4 @@ obj-$(CONFIG_FS_ENET) += fs_enet/
obj-$(CONFIG_FS_ENET) += fs_enet/

obj-$(CONFIG_NETXEN_NIC) += netxen/
+obj-$(CONFIG_LGUEST_GUEST) += lguest_net.o
===================================================================
--- /dev/null
+++ b/drivers/net/lguest_net.c
@@ -0,0 +1,355 @@
+/* A simple network driver for lguest.
+ *
+ * Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+//#define DEBUG
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/module.h>
+#include <linux/mm_types.h>
+#include <linux/lguest_bus.h>
+#include <asm/io.h>
+
+#define SHARED_SIZE PAGE_SIZE
+#define MAX_LANS 4
+#define NUM_SKBS 8
+
+struct lguestnet_info
+{
+ /* The shared page(s). */
+ struct lguest_net *peer;
+ unsigned long peer_phys;
+ unsigned long mapsize;
+
+ /* My peerid. */
+ unsigned int me;
+
+ struct net_device_stats stats;
+
+ /* Receive queue. */
+ struct sk_buff *skb[NUM_SKBS];
+ struct lguest_dma dma[NUM_SKBS];
+};
+
+/* How many bytes left in this page. */
+static unsigned int rest_of_page(void *data)
+{
+ return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
+}
+
+/* Simple convention: offset 4 * peernum. */
+static unsigned long peer_key(struct lguestnet_info *info, unsigned peernum)
+{
+ return info->peer_phys + 4 * peernum;
+}
+
+static void skb_to_dma(const struct sk_buff *skb, unsigned int headlen,
+ struct lguest_dma *dma)
+{
+ unsigned int i, seg;
+
+ for (i = seg = 0; i < headlen; seg++, i += rest_of_page(skb->data+i)) {
+ dma->addr[seg] = virt_to_phys(skb->data + i);
+ dma->len[seg] = min((unsigned)(headlen - i),
+ rest_of_page(skb->data + i));
+ }
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++, seg++) {
+ const skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+ /* Should not happen with MTU less than 64k - 2 * PAGE_SIZE. */
+ if (seg == LGUEST_MAX_DMA_SECTIONS) {
+ printk("Woah dude! Megapacket!\n");
+ break;
+ }
+ dma->addr[seg] = page_to_phys(f->page) + f->page_offset;
+ dma->len[seg] = f->size;
+ }
+ if (seg < LGUEST_MAX_DMA_SECTIONS)
+ dma->len[seg] = 0;
+}
+
+/* We overload multicast bit to show promiscuous mode. */
+#define PROMISC_BIT 0x01
+
+static void lguestnet_set_multicast(struct net_device *dev)
+{
+ struct lguestnet_info *info = dev->priv;
+
+ if ((dev->flags & (IFF_PROMISC|IFF_ALLMULTI)) || dev->mc_count)
+ info->peer[info->me].mac[0] |= PROMISC_BIT;
+ else
+ info->peer[info->me].mac[0] &= ~PROMISC_BIT;
+}
+
+static int promisc(struct lguestnet_info *info, unsigned int peer)
+{
+ return info->peer[peer].mac[0] & PROMISC_BIT;
+}
+
+static int mac_eq(const unsigned char mac[ETH_ALEN],
+ struct lguestnet_info *info, unsigned int peer)
+{
+ /* Ignore multicast bit, which peer turns on to mean promisc. */
+ if ((info->peer[peer].mac[0] & (~PROMISC_BIT)) != mac[0])
+ return 0;
+ return memcmp(mac+1, info->peer[peer].mac+1, ETH_ALEN-1) == 0;
+}
+
+static void transfer_packet(struct net_device *dev,
+ struct sk_buff *skb,
+ unsigned int peernum)
+{
+ struct lguestnet_info *info = dev->priv;
+ struct lguest_dma dma;
+
+ skb_to_dma(skb, skb_headlen(skb), &dma);
+ pr_debug("xfer length %04x (%u)\n", htons(skb->len), skb->len);
+
+ hcall(LHCALL_SEND_DMA, peer_key(info,peernum), __pa(&dma), 0);
+ if (dma.used_len != skb->len) {
+ info->stats.tx_carrier_errors++;
+ pr_debug("Bad xfer to peer %i: %i of %i (dma %p/%i)\n",
+ peernum, dma.used_len, skb->len,
+ (void *)dma.addr[0], dma.len[0]);
+ } else {
+ info->stats.tx_bytes += skb->len;
+ info->stats.tx_packets++;
+ }
+}
+
+static int unused_peer(const struct lguest_net peer[], unsigned int num)
+{
+ return peer[num].mac[0] == 0;
+}
+
+static int lguestnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ unsigned int i;
+ int broadcast;
+ struct lguestnet_info *info = dev->priv;
+ const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
+
+ pr_debug("%s: xmit %02x:%02x:%02x:%02x:%02x:%02x\n",
+ dev->name, dest[0],dest[1],dest[2],dest[3],dest[4],dest[5]);
+
+ broadcast = is_multicast_ether_addr(dest);
+ for (i = 0; i < info->mapsize/sizeof(struct lguest_net); i++) {
+ if (i == info->me || unused_peer(info->peer, i))
+ continue;
+
+ if (!broadcast && !promisc(info, i) && !mac_eq(dest, info, i))
+ continue;
+
+ pr_debug("lguestnet %s: sending from %i to %i\n",
+ dev->name, info->me, i);
+ transfer_packet(dev, skb, i);
+ }
+ dev_kfree_skb(skb);
+ return 0;
+}
+
+/* Find a new skb to put in this slot in shared mem. */
+static int fill_slot(struct net_device *dev, unsigned int slot)
+{
+ struct lguestnet_info *info = dev->priv;
+ /* Try to create and register a new one. */
+ info->skb[slot] = netdev_alloc_skb(dev, ETH_HLEN + ETH_DATA_LEN);
+ if (!info->skb[slot]) {
+ printk("%s: could not fill slot %i\n", dev->name, slot);
+ return -ENOMEM;
+ }
+
+ skb_to_dma(info->skb[slot], ETH_HLEN + ETH_DATA_LEN, &info->dma[slot]);
+ wmb();
+ /* Now we tell hypervisor it can use the slot. */
+ info->dma[slot].used_len = 0;
+ return 0;
+}
+
+static irqreturn_t lguestnet_rcv(int irq, void *dev_id)
+{
+ struct net_device *dev = dev_id;
+ struct lguestnet_info *info = dev->priv;
+ unsigned int i, done = 0;
+
+ for (i = 0; i < ARRAY_SIZE(info->dma); i++) {
+ unsigned int length;
+ struct sk_buff *skb;
+
+ length = info->dma[i].used_len;
+ if (length == 0)
+ continue;
+
+ done++;
+ skb = info->skb[i];
+ fill_slot(dev, i);
+
+ if (length < ETH_HLEN || length > ETH_HLEN + ETH_DATA_LEN) {
+ pr_debug(KERN_WARNING "%s: unbelievable skb len: %i\n",
+ dev->name, length);
+ dev_kfree_skb(skb);
+ continue;
+ }
+
+ skb_put(skb, length);
+ skb->protocol = eth_type_trans(skb, dev);
+ /* This is a reliable transport. */
+ if (dev->features & NETIF_F_NO_CSUM)
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
+ ntohs(skb->protocol), skb->len, skb->pkt_type);
+
+ info->stats.rx_bytes += skb->len;
+ info->stats.rx_packets++;
+ netif_rx(skb);
+ }
+ return done ? IRQ_HANDLED : IRQ_NONE;
+}
+
+static int lguestnet_open(struct net_device *dev)
+{
+ int i;
+ struct lguestnet_info *info = dev->priv;
+
+ /* Set up our MAC address */
+ memcpy(info->peer[info->me].mac, dev->dev_addr, ETH_ALEN);
+
+ /* Turn on promisc mode if needed */
+ lguestnet_set_multicast(dev);
+
+ for (i = 0; i < ARRAY_SIZE(info->dma); i++) {
+ if (fill_slot(dev, i) != 0)
+ goto cleanup;
+ }
+ if (!hcall(LHCALL_BIND_DMA, peer_key(info, info->me), __pa(info->dma),
+ (NUM_SKBS << 8) | dev->irq))
+ goto cleanup;
+ return 0;
+
+cleanup:
+ while (--i >= 0)
+ dev_kfree_skb(info->skb[i]);
+ return -ENOMEM;
+}
+
+static int lguestnet_close(struct net_device *dev)
+{
+ unsigned int i;
+ struct lguestnet_info *info = dev->priv;
+
+ /* Clear all trace: others might deliver packets, we'll ignore it. */
+ memset(&info->peer[info->me], 0xFF, sizeof(info->peer[info->me]));
+
+ /* Deregister sg lists. */
+ hcall(LHCALL_BIND_DMA, peer_key(info, info->me), __pa(info->dma), 0);
+ for (i = 0; i < ARRAY_SIZE(info->dma); i++)
+ dev_kfree_skb(info->skb[i]);
+ return 0;
+}
+
+static struct net_device_stats *lguestnet_get_stats(struct net_device *dev)
+{
+ struct lguestnet_info *info = dev->priv;
+
+ return &info->stats;
+}
+
+static int lguestnet_probe(struct lguest_device *lgdev)
+{
+ int err, irqf = IRQF_SHARED;
+ struct net_device *dev;
+ struct lguestnet_info *info;
+ struct lguest_device_desc *desc = &lguest_devices[lgdev->index];
+
+ pr_debug("lguest_net: probing for device %i\n", lgdev->index);
+
+ dev = alloc_etherdev(sizeof(struct lguestnet_info));
+ if (!dev)
+ return -ENOMEM;
+
+ SET_MODULE_OWNER(dev);
+
+ /* Ethernet defaults with some changes */
+ ether_setup(dev);
+ dev->set_mac_address = NULL;
+
+ dev->dev_addr[0] = 0x02; /* set local assignment bit (IEEE802) */
+ dev->dev_addr[1] = 0x00;
+ memcpy(&dev->dev_addr[2], &lguest_data.guestid, 2);
+ dev->dev_addr[4] = 0x00;
+ dev->dev_addr[5] = 0x00;
+
+ dev->open = lguestnet_open;
+ dev->stop = lguestnet_close;
+ dev->hard_start_xmit = lguestnet_start_xmit;
+ dev->get_stats = lguestnet_get_stats;
+
+ /* Turning on/off promisc will call dev->set_multicast_list.
+ * We don't actually support multicast yet */
+ dev->set_multicast_list = lguestnet_set_multicast;
+ dev->mem_start = ((unsigned long)desc->pfn << PAGE_SHIFT);
+ dev->mem_end = dev->mem_start + PAGE_SIZE * desc->num_pages;
+ dev->irq = lgdev->index+1;
+ dev->features = NETIF_F_SG;
+ if (desc->features & LGUEST_NET_F_NOCSUM)
+ dev->features |= NETIF_F_NO_CSUM;
+
+ info = dev->priv;
+ info->mapsize = PAGE_SIZE * desc->num_pages;
+ info->peer_phys = ((unsigned long)desc->pfn << PAGE_SHIFT);
+ info->peer = (void *)ioremap(info->peer_phys, info->mapsize);
+ /* This stores our peerid (upper bits reserved for future). */
+ info->me = (desc->features & (info->mapsize-1));
+
+ err = register_netdev(dev);
+ if (err) {
+ pr_debug("lguestnet: registering device failed\n");
+ goto free;
+ }
+
+ if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
+ irqf |= IRQF_SAMPLE_RANDOM;
+ if (request_irq(dev->irq, lguestnet_rcv, irqf, "lguestnet", dev) != 0) {
+ pr_debug("lguestnet: could not get net irq %i\n", dev->irq);
+ goto unregister;
+ }
+
+ pr_debug("lguestnet: registered device %s\n", dev->name);
+ lgdev->private = dev;
+ return 0;
+
+unregister:
+ unregister_netdev(dev);
+free:
+ free_netdev(dev);
+ return err;
+}
+
+static struct lguest_driver lguestnet_drv = {
+ .name = "lguestnet",
+ .owner = THIS_MODULE,
+ .device_type = LGUEST_DEVICE_T_NET,
+ .probe = lguestnet_probe,
+};
+
+static __init int lguestnet_init(void)
+{
+ return register_lguest_driver(&lguestnet_drv);
+}
+module_init(lguestnet_init);
+
+MODULE_DESCRIPTION("Lguest network driver");
+MODULE_LICENSE("GPL");

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