First look in /var/log/libvirt/qemu/<domainname>.log and see which qemu binary is being executed by libvirt - it may not be the one you've built.
It looks correct... I pulled out the driver tag from my config and fired it up. Here is the full command line for it:
LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin QEMU_AUDIO_DRV=none /usr/local/bin/qemu-system-x86_64 -S -M pc-0.14 -enable-kvm -m 4096 -smp 7,sockets=7,cores=1,threads=1 -name web101 -uuid bda63821-ccc4-6607-67c0-db6712526cbd -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/web101.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=readline -rtc base=utc -boot c -drive file=/var/lib/libvirt/images/web101.img,if=none,id=drive-virtio-disk0,format=raw,cache=writethrough -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -drive file=/home/httpd.img,if=none,id=drive-virtio-disk1,format=raw,cache=writethrough -device virtio-blk-pci,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1 -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -fsdev local,security_model=passthrough,id=fsdev-fs0,path=/home/httpd -device virtio-9p-pci,id=fs0,fsdev=fsdev-fs0,mount_tag=/home/httpd,bus=pci.0,addr=0x8 -netdev tap,fd=15,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:6f:51:43,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -usb -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -vga cirrus -device AC97,id=sound0,bus=pci.0,addr=0x4 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6
Then, run "qemu-kvm --help" (replacing "qemu-kvm" with the path to the binary that libvirt is executing, found in the previous paragraph), and search through that output for the string ",vhost=" - if it's not there, then your qemu doesn't support vhost-net.
This also looks correct. Is it wrong that my qemu compilation didn't create a binary named "qemu-kvm"? (Even though it said "KVM support yes" on the configure output?)
# /usr/local/bin/qemu-system-x86_64 --help |grep vhost
-net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h][,vhostforce=on|off]
use vhost=on to enable experimental in kernel accelerator
use vhostforce=on to force vhost on for non-MSIX virtio guests
use 'vhostfd=h' to connect to an already opened vhost net device
If that string *is* there, then we need to do some more investigating, starting with you sending the output of "qemu-kvm --help".
Here's the full output for you.
# /usr/local/bin/qemu-system-x86_64 --help
QEMU emulator version 0.14.1, Copyright (c) 2003-2008 Fabrice Bellard
usage: qemu [options] [disk_image]
'disk_image' is a raw hard disk image for IDE hard disk 0
Standard options:
-h or -help display this help and exit
-version display version information and exit
-M machine select emulated machine (-M ? for list)
-cpu cpu select CPU (-cpu ? for list)
-smp n[,maxcpus=cpus][,cores=cores][,threads=threads][,sockets=sockets]
set the number of CPUs to 'n' [default=1]
maxcpus= maximum number of total cpus, including
offline CPUs for hotplug, etc
cores= number of CPU cores on one socket
threads= number of threads on one CPU core
sockets= number of discrete sockets in the system
-numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node]
-fda/-fdb file use 'file' as floppy disk 0/1 image
-hda/-hdb file use 'file' as IDE hard disk 0/1 image
-hdc/-hdd file use 'file' as IDE hard disk 2/3 image
-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)
-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]
[,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]
[,cache=writethrough|writeback|none|unsafe][,format=f]
[,serial=s][,addr=A][,id=name][,aio=threads|native]
[,readonly=on|off]
use 'file' as a drive image
-set group.id.arg=value
set <arg> parameter for item <id> of type <group>
i.e. -set drive.$id.file=/path/to/image
-global driver.property=value
set a global default for a driver property
-mtdblock file use 'file' as on-board Flash memory image
-sd file use 'file' as SecureDigital card image
-pflash file use 'file' as a parallel flash image
-boot [order=drives][,once=drives][,menu=on|off]
'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)
-snapshot write to temporary files instead of disk image files
-m megs set virtual RAM size to megs MB [default=128]
-mem-path FILE provide backing storage for guest RAM
-mem-prealloc preallocate guest memory (use with -mem-path)
-k language use keyboard layout (for example 'fr' for French)
-audio-help print list of audio drivers and their options
-soundhw c1,... enable audio support
and only specified sound cards (comma separated list)
use -soundhw ? to get the list of supported cards
use -soundhw all to enable all of them
-usb enable the USB driver (will be the default soon)
-usbdevice name add the host or guest USB device 'name'
-device driver[,prop[=value][,...]]
add device (based on driver)
prop=value,... sets driver properties
use -device ? to print all possible drivers
use -device driver,? to print all possible properties
File system options:
-fsdev local,id=id,path=path,security_model=[mapped|passthrough|none]
Virtual File system pass-through options:
-virtfs local,path=path,mount_tag=tag,security_model=[mapped|passthrough|none]
-name string1[,process=string2]
set the name of the guest
string1 sets the window title and string2 the process name (on Linux)
-uuid %08x-%04x-%04x-%04x-%012x
specify machine UUID
Display options:
-nographic disable graphical output and redirect serial I/Os to console
-spice <args> enable spice
-portrait rotate graphical output 90 deg left (only PXA LCD)
-vga [std|cirrus|vmware|qxl|xenfb|none]
select video card type
-full-screen start in full screen
-g WxH[xDEPTH] Set the initial graphical resolution and depth
-vnc display start a VNC server on display
i386 target only:
-win2k-hack use it when installing Windows 2000 to avoid a disk full bug
-no-fd-bootchk disable boot signature checking for floppy disks
-no-acpi disable ACPI
-no-hpet disable HPET
-balloon none disable balloon device
-balloon virtio[,addr=str]
enable virtio balloon device (default)
-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n][,asl_compiler_id=str][,asl_compiler_rev=n][,data=file1[:file2]...]
ACPI table description
-smbios file=binary
load SMBIOS entry from binary file
-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]
specify SMBIOS type 0 fields
-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]
[,uuid=uuid][,sku=str][,family=str]
specify SMBIOS type 1 fields
Network options:
-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]
create a new Network Interface Card and connect it to VLAN 'n'
-net user[,vlan=n][,name=str][,net=addr[/mask]][,host=addr][,restrict=y|n]
[,hostname=host][,dhcpstart=addr][,dns=addr][,tftp=dir][,bootfile=f]
[,hostfwd=rule][,guestfwd=rule][,smb=dir[,smbserver=addr]]
connect the user mode network stack to VLAN 'n', configure its
DHCP server and enabled optional services
-net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h][,vhostforce=on|off]
connect the host TAP network interface to VLAN 'n' and use the
network scripts 'file' (default=/etc/qemu-ifup)
and 'dfile' (default=/etc/qemu-ifdown)
use '[down]script=no' to disable script execution
use 'fd=h' to connect to an already opened TAP interface
use 'sndbuf=nbytes' to limit the size of the send buffer (the
default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')
use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag
use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition
use vhost=on to enable experimental in kernel accelerator
(only has effect for virtio guests which use MSIX)
use vhostforce=on to force vhost on for non-MSIX virtio guests
use 'vhostfd=h' to connect to an already opened vhost net device
-net socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port]
connect the vlan 'n' to another VLAN using a socket connection
-net socket[,vlan=n][,name=str][,fd=h][,mcast=maddr:port[,localaddr=addr]]
connect the vlan 'n' to multicast maddr and port
use 'localaddr=addr' to specify the host address to send packets from
-net dump[,vlan=n][,file=f][,len=n]
dump traffic on vlan 'n' to file 'f' (max n bytes per packet)
-net none use it alone to have zero network devices. If no -net option
is provided, the default is '-net nic -net user'
-netdev [user|tap|socket],id=str[,option][,option][,...]
Character device options:
-chardev null,id=id[,mux=on|off]
-chardev socket,id=id[,host=host],port=host[,to=to][,ipv4][,ipv6][,nodelay]
[,server][,nowait][,telnet][,mux=on|off] (tcp)
-chardev socket,id=id,path=path[,server][,nowait][,telnet],[mux=on|off] (unix)
-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]
[,localport=localport][,ipv4][,ipv6][,mux=on|off]
-chardev msmouse,id=id[,mux=on|off]
-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]
[,mux=on|off]
-chardev file,id=id,path=path[,mux=on|off]
-chardev pipe,id=id,path=path[,mux=on|off]
-chardev pty,id=id[,mux=on|off]
-chardev stdio,id=id[,mux=on|off][,signal=on|off]
-chardev tty,id=id,path=path[,mux=on|off]
-chardev parport,id=id,path=path[,mux=on|off]
Bluetooth(R) options:
-bt hci,null dumb bluetooth HCI - doesn't respond to commands
-bt hci,host[:id]
use host's HCI with the given name
-bt hci[,vlan=n]
emulate a standard HCI in virtual scatternet 'n'
-bt vhci[,vlan=n]
add host computer to virtual scatternet 'n' using VHCI
-bt device:dev[,vlan=n]
emulate a bluetooth device 'dev' in scatternet 'n'
Linux/Multiboot boot specific:
-kernel bzImage use 'bzImage' as kernel image
-append cmdline use 'cmdline' as kernel command line
-initrd file use 'file' as initial ram disk
Debug/Expert options:
-serial dev redirect the serial port to char device 'dev'
-parallel dev redirect the parallel port to char device 'dev'
-monitor dev redirect the monitor to char device 'dev'
-qmp dev like -monitor but opens in 'control' mode
-mon chardev=[name][,mode=readline|control][,default]
-debugcon dev redirect the debug console to char device 'dev'
-pidfile file write PID to 'file'
-singlestep always run in singlestep mode
-S freeze CPU at startup (use 'c' to start execution)
-gdb dev wait for gdb connection on 'dev'
-s shorthand for -gdb tcp::1234
-d item1,... output log to /tmp/qemu.log (use -d ? for a list of log items)
-hdachs c,h,s[,t]
force hard disk 0 physical geometry and the optional BIOS
translation (t=none or lba) (usually qemu can guess them)
-L path set the directory for the BIOS, VGA BIOS and keymaps
-bios file set the filename for the BIOS
-enable-kvm enable KVM full virtualization support
-xen-domid id specify xen guest domain id
-xen-create create domain using xen hypercalls, bypassing xend
warning: should not be used when xend is in use
-xen-attach attach to existing xen domain
xend will use this when starting qemu
-no-reboot exit instead of rebooting
-no-shutdown stop before shutdown
-loadvm [tag|id]
start right away with a saved state (loadvm in monitor)
-daemonize daemonize QEMU after initializing
-option-rom rom load a file, rom, into the option ROM space
-clock force the use of the given methods for timer alarm.
To see what timers are available use -clock ?
-rtc [base=utc|localtime|date][,clock=host|vm][,driftfix=none|slew]
set the RTC base and clock, enable drift fix for clock ticks (x86 only)
-icount [N|auto]
enable virtual instruction counter with 2^N clock ticks per
instruction
-watchdog i6300esb|ib700
enable virtual hardware watchdog [default=none]
-watchdog-action reset|shutdown|poweroff|pause|debug|none
action when watchdog fires [default=reset]
-echr chr set terminal escape character instead of ctrl-a
-virtioconsole c
set virtio console
-show-cursor show cursor
-tb-size n set TB size
-incoming p prepare for incoming migration, listen on port p
-nodefaults don't create default devices
-chroot dir chroot to dir just before starting the VM
-runas user change to user id user just before starting the VM
-prom-env variable=value
set OpenBIOS nvram variables
-semihosting semihosting mode
-old-param old param mode
-readconfig <file>
-writeconfig <file>
read/write config file
-nodefconfig
do not load default config files at startup
During emulation, the following keys are useful:
ctrl-alt-f toggle full screen
ctrl-alt-n switch to virtual console 'n'
ctrl-alt toggle mouse and keyboard grab
When using -nographic, press 'ctrl-a h' to get some help.