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Add XML config switch to enable/disable vhost-net support

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This patch is in response to

  https://bugzilla.redhat.com/show_bug.cgi?id=643050

The existing libvirt support for the vhost-net backend to the virtio
network driver happens automatically - if the vhost-net device is
available, it is always enabled, otherwise the standard userland
virtio backend is used.

This patch makes it possible to force whether or not vhost-net is used
with a bit of XML. Adding a <driver> element to the interface XML, eg:

     <interface type="network">
       <model type="virtio"/>
       <driver name="vhost"/>

will force use of vhost-net (if it's not available, the domain will
fail to start). if driver name="qemu", vhost-net will not be used even
if it is available.

If there is no <driver name='xxx'/> in the config, libvirt will revert
to the pre-existing automatic behavior - use vhost-net if it's
available, and userland backend if vhost-net isn't available.
This commit is contained in:
Laine Stump 2011-01-11 23:18:49 -05:00
parent 9d73efdbe3
commit 175077fd70
5 changed files with 106 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
docs/schemas/domain.rng
View File

@ -1004,6 +1004,19 @@
<empty/>
</element>
</optional>
<optional>
<element name="driver">
<optional>
<attribute name="name">
<choice>
<value>qemu</value>
<value>vhost</value>
</choice>
</attribute>
</optional>
<empty/>
</element>
</optional>
<optional>
<ref name="address"/>
</optional>

29
src/conf/domain_conf.c
View File

@ -185,6 +185,11 @@ VIR_ENUM_IMPL(virDomainNet, VIR_DOMAIN_NET_TYPE_LAST,
"internal",
"direct")
VIR_ENUM_IMPL(virDomainNetBackend, VIR_DOMAIN_NET_BACKEND_TYPE_LAST,
"default",
"qemu",
"vhost")
VIR_ENUM_IMPL(virDomainChrChannelTarget,
VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_LAST,
"guestfwd",
@ -2304,6 +2309,7 @@ virDomainNetDefParseXML(virCapsPtr caps,
char *address = NULL;
char *port = NULL;
char *model = NULL;
char *backend = NULL;
char *filter = NULL;
char *internal = NULL;
char *devaddr = NULL;
@ -2386,6 +2392,8 @@ virDomainNetDefParseXML(virCapsPtr caps,
script = virXMLPropString(cur, "path");
} else if (xmlStrEqual (cur->name, BAD_CAST "model")) {
model = virXMLPropString(cur, "type");
} else if (xmlStrEqual (cur->name, BAD_CAST "driver")) {
backend = virXMLPropString(cur, "name");
} else if (xmlStrEqual (cur->name, BAD_CAST "filterref")) {
filter = virXMLPropString(cur, "filter");
VIR_FREE(filterparams);
@ -2573,6 +2581,19 @@ virDomainNetDefParseXML(virCapsPtr caps,
model = NULL;
}
if ((backend != NULL) &&
(def->model && STREQ(def->model, "virtio"))) {
int b;
if (((b = virDomainNetBackendTypeFromString(backend)) < 0) ||
(b == VIR_DOMAIN_NET_BACKEND_TYPE_DEFAULT)) {
virDomainReportError(VIR_ERR_INTERNAL_ERROR,
_("Unknown interface <driver name='%s'> "
"has been specified"),
backend);
goto error;
}
def->backend = b;
}
if (filter != NULL) {
switch (def->type) {
case VIR_DOMAIN_NET_TYPE_ETHERNET:
@ -2599,6 +2620,7 @@ cleanup:
VIR_FREE(script);
VIR_FREE(bridge);
VIR_FREE(model);
VIR_FREE(backend);
VIR_FREE(filter);
VIR_FREE(type);
VIR_FREE(internal);
@ -6318,9 +6340,14 @@ virDomainNetDefFormat(virBufferPtr buf,
if (def->ifname)
virBufferEscapeString(buf, " <target dev='%s'/>\n",
def->ifname);
if (def->model)
if (def->model) {
virBufferEscapeString(buf, " <model type='%s'/>\n",
def->model);
if (STREQ(def->model, "virtio") && def->backend) {
virBufferVSprintf(buf, " <driver name='%s'/>\n",
virDomainNetBackendTypeToString(def->backend));
}
}
if (def->filter) {
virBufferEscapeString(buf, " <filterref filter='%s'",
def->filter);

10
src/conf/domain_conf.h
View File

@ -292,6 +292,14 @@ enum virDomainNetType {
VIR_DOMAIN_NET_TYPE_LAST,
};
/* the backend driver used for virtio interfaces */
enum virDomainNetBackendType {
VIR_DOMAIN_NET_BACKEND_TYPE_DEFAULT, /* prefer kernel, fall back to user */
VIR_DOMAIN_NET_BACKEND_TYPE_QEMU, /* userland */
VIR_DOMAIN_NET_BACKEND_TYPE_VHOST, /* kernel */
VIR_DOMAIN_NET_BACKEND_TYPE_LAST,
};
/* the mode type for macvtap devices */
enum virDomainNetdevMacvtapType {
@ -310,6 +318,7 @@ struct _virDomainNetDef {
enum virDomainNetType type;
unsigned char mac[VIR_MAC_BUFLEN];
char *model;
enum virDomainNetBackendType backend;
union {
struct {
char *dev;
@ -1273,6 +1282,7 @@ VIR_ENUM_DECL(virDomainControllerModel)
VIR_ENUM_DECL(virDomainFS)
VIR_ENUM_DECL(virDomainFSAccessMode)
VIR_ENUM_DECL(virDomainNet)
VIR_ENUM_DECL(virDomainNetBackend)
VIR_ENUM_DECL(virDomainChrDevice)
VIR_ENUM_DECL(virDomainChrChannelTarget)
VIR_ENUM_DECL(virDomainChrConsoleTarget)

67
src/qemu/qemu_command.c
View File

@ -302,24 +302,58 @@ cleanup:
}
int
static int
qemuOpenVhostNet(virDomainNetDefPtr net,
unsigned long long qemuCmdFlags)
unsigned long long qemuCmdFlags,
int *vhostfd)
{
/* If qemu supports vhost-net mode (including the -netdev command
* option), the nic model is virtio, and we can open
* /dev/vhost_net, assume that vhost-net mode is available and
* return the fd to /dev/vhost_net. Otherwise, return -1.
*/
*vhostfd = -1; /* assume we won't use vhost */
/* If the config says explicitly to not use vhost, return now */
if (net->backend == VIR_DOMAIN_NET_BACKEND_TYPE_QEMU) {
return 0;
}
/* If qemu doesn't support vhost-net mode (including the -netdev command
* option), don't try to open the device.
*/
if (!(qemuCmdFlags & QEMUD_CMD_FLAG_VNET_HOST &&
qemuCmdFlags & QEMUD_CMD_FLAG_NETDEV &&
qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE &&
net->model && STREQ(net->model, "virtio")))
return -1;
qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE)) {
if (net->backend == VIR_DOMAIN_NET_BACKEND_TYPE_VHOST) {
qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
"%s", _("vhost-net is not supported with "
"this QEMU binary"));
return -1;
}
return 0;
}
return open("/dev/vhost-net", O_RDWR, 0);
/* If the nic model isn't virtio, don't try to open. */
if (!(net->model && STREQ(net->model, "virtio"))) {
if (net->backend == VIR_DOMAIN_NET_BACKEND_TYPE_VHOST) {
qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
"%s", _("vhost-net is only supported for "
"virtio network interfaces"));
return -1;
}
return 0;
}
*vhostfd = open("/dev/vhost-net", O_RDWR);
/* If the config says explicitly to use vhost and we couldn't open it,
* report an error.
*/
if ((*vhostfd < 0) &&
(net->backend == VIR_DOMAIN_NET_BACKEND_TYPE_VHOST)) {
qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
"%s", _("vhost-net was requested for an interface, "
"but is unavailable"));
return -1;
}
return 0;
}
@ -3281,7 +3315,10 @@ qemuBuildCommandLine(virConnectPtr conn,
net->type == VIR_DOMAIN_NET_TYPE_DIRECT) {
/* Attempt to use vhost-net mode for these types of
network device */
int vhostfd = qemuOpenVhostNet(net, qemuCmdFlags);
int vhostfd;
if (qemuOpenVhostNet(net, qemuCmdFlags, &vhostfd) < 0)
goto error;
if (vhostfd >= 0) {
virCommandTransferFD(cmd, vhostfd);
@ -4626,6 +4663,12 @@ qemuParseCommandLineNet(virCapsPtr caps,
} else if (STREQ(keywords[i], "model")) {
def->model = values[i];
values[i] = NULL;
} else if (STREQ(keywords[i], "vhost")) {
if ((values[i] == NULL) || STREQ(values[i], "on")) {
def->backend = VIR_DOMAIN_NET_BACKEND_TYPE_VHOST;
} else if (STREQ(keywords[i], "off")) {
def->backend = VIR_DOMAIN_NET_BACKEND_TYPE_QEMU;
}
}
}

3
src/qemu/qemu_command.h
View File

@ -111,9 +111,6 @@ int qemuNetworkIfaceConnect(virConnectPtr conn,
unsigned long long qemCmdFlags)
ATTRIBUTE_NONNULL(1);
int qemuOpenVhostNet(virDomainNetDefPtr net,
unsigned long long qemuCmdFlags);
int qemuPhysIfaceConnect(virConnectPtr conn,
struct qemud_driver *driver,
virDomainNetDefPtr net,