On Thu, Feb 25, 2010 at 01:47:27PM -0600, Anthony Liguori wrote:
> On 02/25/2010 12:28 PM, Michael S. Tsirkin wrote:
>> This adds vhost binary option to tap, to enable vhost net accelerator.
>> Default is off for now, we'll be able to make default on long term
>> when we know it's stable.
>>
>> vhostfd option can be used by management, to pass in the fd. Assigning
>> vhostfd implies vhost=on.
>>
>> Signed-off-by: Michael S. Tsirkin<m...@redhat.com>
>>
>
> Since the thinking these days is that macvtap and tap is pretty much all
> we'll ever need for vhost-net, perhaps we should revisit -net vhost vs.
> -net tap,vhost=X?
>
> I think -net vhost,fd=X makes a lot more sense than -net
> tap,vhost=on,vhostfd=X.
>
> Regards,
>
> Anthony Liguori
We'll have to duplicate all tap options.
I think long term we will just make vhost=on the default.
Users do not really care about vhost, it just makes tap
go fater. So promoting it to 1st class options is wrong IMO.
>> ---
>> net.c | 8 ++++++++
>> net/tap.c | 33 +++++++++++++++++++++++++++++++++
>> qemu-options.hx | 4 +++-
>> 3 files changed, 44 insertions(+), 1 deletions(-)
>>
>> diff --git a/net.c b/net.c
>> index a1bf49f..d1e23f1 100644
>> --- a/net.c
>> +++ b/net.c
>> @@ -973,6 +973,14 @@ static const struct {
>> .name = "vnet_hdr",
>> .type = QEMU_OPT_BOOL,
>> .help = "enable the IFF_VNET_HDR flag on the tap interface"
>> + }, {
>> + .name = "vhost",
>> + .type = QEMU_OPT_BOOL,
>> + .help = "enable vhost-net network accelerator",
>> + }, {
>> + .name = "vhostfd",
>> + .type = QEMU_OPT_STRING,
>> + .help = "file descriptor of an already opened vhost net
>> device",
>> },
>> #endif /* _WIN32 */
>> { /* end of list */ }
>> diff --git a/net/tap.c b/net/tap.c
>> index fc59fd4..65797ef 100644
>> --- a/net/tap.c
>> +++ b/net/tap.c
>> @@ -41,6 +41,8 @@
>>
>> #include "net/tap-linux.h"
>>
>> +#include "hw/vhost_net.h"
>> +
>> /* Maximum GSO packet size (64k) plus plenty of room for
>> * the ethernet and virtio_net headers
>> */
>> @@ -57,6 +59,7 @@ typedef struct TAPState {
>> unsigned int has_vnet_hdr : 1;
>> unsigned int using_vnet_hdr : 1;
>> unsigned int has_ufo: 1;
>> + struct vhost_net *vhost_net;
>> } TAPState;
>>
>> static int launch_script(const char *setup_script, const char *ifname, int
>> fd);
>> @@ -252,6 +255,10 @@ static void tap_cleanup(VLANClientState *nc)
>> {
>> TAPState *s = DO_UPCAST(TAPState, nc, nc);
>>
>> + if (s->vhost_net) {
>> + vhost_net_cleanup(s->vhost_net);
>> + }
>> +
>> qemu_purge_queued_packets(nc);
>>
>> if (s->down_script[0])
>> @@ -307,6 +314,7 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
>> s->has_ufo = tap_probe_has_ufo(s->fd);
>> tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
>> tap_read_poll(s, 1);
>> + s->vhost_net = NULL;
>> return s;
>> }
>>
>> @@ -456,5 +464,30 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const
>> char *name, VLANState *vlan
>> }
>> }
>>
>> + if (qemu_opt_get_bool(opts, "vhost", !!qemu_opt_get(opts, "vhostfd"))) {
>> + int vhostfd, r;
>> + if (qemu_opt_get(opts, "vhostfd")) {
>> + r = net_handle_fd_param(mon, qemu_opt_get(opts, "vhostfd"));
>> + if (r == -1) {
>> + return -1;
>> + }
>> + vhostfd = r;
>> + } else {
>> + vhostfd = -1;
>> + }
>> + s->vhost_net = vhost_net_init(&s->nc, vhostfd);
>> + if (!s->vhost_net) {
>> + qemu_error("vhost-net requested but could not be
>> initialized\n");
>> + return -1;
>> + }
>> + } else if (qemu_opt_get(opts, "vhostfd")) {
>> + qemu_error("vhostfd= is not valid without vhost\n");
>> + return -1;
>> + }
>> +
>> + if (vlan) {
>> + vlan->nb_host_devs++;
>> + }
>> +
>> return 0;
>> }
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index f53922f..1850906 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -879,7 +879,7 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
>> "-net tap[,vlan=n][,name=str],ifname=name\n"
>> " connect the host TAP network interface to VLAN 'n'\n"
>> #else
>> - "-net
>> tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off]\n"
>> + "-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]\n"
>> " connect the host TAP network interface to VLAN 'n'
>> and use the\n"
>> " network scripts 'file' (default="
>> DEFAULT_NETWORK_SCRIPT ")\n"
>> " and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT
>> ")\n"
>> @@ -889,6 +889,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
>> " default of 'sndbuf=1048576' can be disabled using
>> 'sndbuf=0')\n"
>> " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR
>> tap flag\n"
>> " use vnet_hdr=on to make the lack of IFF_VNET_HDR
>> support an error condition\n"
>> + " use vhost=on to enable experimental in kernel
>> accelerator\n"
>> + " use 'vhostfd=h' to connect to an already opened vhost
>> net device\n"
>> #endif
>> "-net
>> socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port]\n"
>> " connect the vlan 'n' to another VLAN using a socket
>> connection\n"
>>
