userspace virtio

From 83e942e0c7634121243478fa2f4e3459b33d4a67 Mon Sep 17 00:00:00 2001
From: Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/[email protected]>
Date: Wed, 19 Dec 2007 23:43:24 +0200
Subject: [PATCH] virtio network device

This patch implements the backend support for the virtio network device. The
device is optimized for virtualized environments by limiting the number of guest=>host transitions per-packet. In the best case, the number of transitions per-packet is < 1.

With some further optimizations, I have been able to obtain 1.5gbit/sec host=>guest with this driver (compared to the 90mbit/sec from the rtl8139 card). This requires additional patches not present in this series.

---
 qemu/Makefile.target |    2 +-
 qemu/hw/pc.h         |    5 ++
 qemu/hw/pci.c        |    5 +-
 qemu/hw/virtio-net.c |  178 
++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 188 insertions(+), 2 deletions(-)
 create mode 100644 qemu/hw/virtio-net.c

index 8b5853b..17ff6f2 100644
@@ -464,7 +464,7 @@ VL_OBJS += rtl8139.o
 VL_OBJS+= hypercall.o
 
 # virtio devices
-VL_OBJS += virtio.o
+VL_OBJS += virtio.o virtio-net.o
 
 ifeq ($(TARGET_BASE_ARCH), i386)
 # Hardware support

index beb711c..ce1a1f3 100644
@@ -142,4 +142,9 @@ void pci_piix4_ide_init(PCIBus *bus, 

BlockDriverState **hd_table, int devfn,

void isa_ne2000_init(int base, qemu_irq irq, NICInfo *nd);

+/* virtio-net.c */
+
+void *virtio_net_init(PCIBus *bus, NICInfo *nd, int devfn); +
+
#endif

index f8cbf1a..545901c 100644
@@ -25,6 +25,7 @@
 #include "pci.h"
 #include "console.h"
 #include "net.h"
+#include "pc.h"
 
 //#define DEBUG_PCI
 

@@ -638,9 +639,11 @@ void pci_nic_init(PCIBus *bus, NICInfo *nd, int devfn)
         pci_rtl8139_init(bus, nd, devfn);
     } else if (strcmp(nd->model, "pcnet") == 0) {
         pci_pcnet_init(bus, nd, devfn);
+    } else if (strcmp(nd->model, "virtio") == 0) {
+    virtio_net_init(bus, nd, devfn);
     } else if (strcmp(nd->model, "?") == 0) {
         fprintf(stderr, "qemu: Supported PCI NICs: i82551 i82557b i82559er"
-                        " ne2k_pci pcnet rtl8139\n");
+                        " ne2k_pci pcnet rtl8139 virtio\n");
         exit (1);
     } else {
         fprintf(stderr, "qemu: Unsupported NIC: %s\n", nd->model);

care? */
+#define VIRTIO_NET_HDR_GSO_TCPV4_ECN 2 // GSO frame, IPv4 TCP w/ ECN
+#define VIRTIO_NET_HDR_GSO_UDP 3 // GSO frame, IPv4 UDP (UFO)
+#define VIRTIO_NET_HDR_GSO_TCPV6 4 // GSO frame, IPv6 TCP

+    uint8_t gso_type;
+    uint16_t gso_size;
+    uint16_t csum_start;
+    uint16_t csum_offset;

+};
+
+typedef struct VirtIONet
+{

+    VirtIODevice vdev;
+    uint8_t mac[6];
+    VirtQueue *rx_vq;
+    VirtQueue *tx_vq;
+    VLANClientState *vc;
+    int can_receive;

+} VirtIONet;
+
+static VirtIONet *to_virtio_net(VirtIODevice *vdev)
+{
+ return (VirtIONet *)vdev;
+}
+
+static void virtio_net_update_config(VirtIODevice *vdev, uint8_t *config) +{
+ VirtIONet *n = to_virtio_net(vdev);
+ struct virtio_net_config netcfg;
+
+ memcpy(netcfg.mac, n->mac, 6);
+ memcpy(config, &netcfg, sizeof(netcfg));
+}
+
+static uint32_t virtio_net_get_features(VirtIODevice *vdev)
+{
+ return (1 << VIRTIO_NET_F_MAC);
+}
+
+/* RX */
+
+static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq) +{
+ VirtIONet *n = to_virtio_net(vdev);
+ n->can_receive = 1;
+}
+
+static int virtio_net_can_receive(void *opaque)
+{
+ VirtIONet *n = opaque;
+
+ return (n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) && n->can_receive;
+}
+
+static void virtio_net_receive(void *opaque, const uint8_t *buf, int size) +{

+    VirtIONet *n = opaque;
+    VirtQueueElement elem;
+    struct virtio_net_hdr *hdr;
+    int offset, i;
+
+    /* FIXME: the drivers really need to set their status better */
+    if (n->rx_vq->vring.avail == NULL) {
+    n->can_receive = 0;
+    return;
+    }
+
+    if (virtqueue_pop(n->rx_vq, &elem) == 0) {
+    /* wait until the guest adds some rx bufs */
+    n->can_receive = 0;
+    return;
+    }
+
+    hdr = (void *)elem.in_sg[0].iov_base;
+    hdr->flags = 0;
+    hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
+
+    /* copy in packet.  ugh */
+    offset = 0;
+    i = 1;
+    while (offset < size && i < elem.in_num) {
+    int len = MIN(elem.in_sg[i].iov_len, size - offset);
+    memcpy(elem.in_sg[i].iov_base, buf + offset, len);
+    offset += len;
+    i++;
+    }
+
+    /* signal other side */
+    virtqueue_push(n->rx_vq, &elem, sizeof(*hdr) + offset);
+    virtio_notify(&n->vdev, n->rx_vq);

+}
+
+/* TX */
+static void virtio_net_handle_tx(VirtIODevice *vdev, VirtQueue *vq) +{
+ VirtIONet *n = to_virtio_net(vdev);
+ VirtQueueElement elem;
+

+    while (virtqueue_pop(vq, &elem)) {
+    int i;
+    size_t len = 0;

+
+ /* ignore the header for now */
+ for (i = 1; i < elem.out_num; i++) {
+ qemu_send_packet(n->vc, elem.out_sg[i].iov_base,
+ elem.out_sg[i].iov_len);
+ len += elem.out_sg[i].iov_len;
+ }
+

+    virtqueue_push(vq, &elem, sizeof(struct virtio_net_hdr) + len);
+    virtio_notify(&n->vdev, vq);
+    }

+}
+
+void *virtio_net_init(PCIBus *bus, NICInfo *nd, int devfn) +{
+ VirtIONet *n;
+
+ n = (VirtIONet *)virtio_init_pci(bus, "virtio-net", 6900, 0x1000,

+                     0, VIRTIO_ID_NET,
+                     0x02, 0x00, 0x00,
+                     6, sizeof(VirtIONet));
+
+    n->vdev.update_config = virtio_net_update_config;
+    n->vdev.get_features = virtio_net_get_features;
+    n->rx_vq = virtio_add_queue(&n->vdev, 512, virtio_net_handle_rx);
+    n->tx_vq = virtio_add_queue(&n->vdev, 128, virtio_net_handle_tx);
+    n->can_receive = 0;
+    memcpy(n->mac, nd->macaddr, 6);
+    n->vc = qemu_new_vlan_client(nd->vlan, virtio_net_receive,

+ virtio_net_can_receive, n);
+
+ return &n->vdev;
+}

1.5.3.3


-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/