October 2023 - Devel - libvirt List Archives

[PATCH V2] support for hotplug/hotunplug in test hypervisor
by Thanos Makatos 30 Oct '23

30 Oct '23

Signed-off-by: Thanos Makatos <thanos.makatos(a)nutanix.com> --- src/test/test_driver.c | 59 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) diff --git a/src/test/test_driver.c b/src/test/test_driver.c index e87d7cfd44..80ef1b3cbb 100644 --- a/src/test/test_driver.c +++ b/src/test/test_driver.c @@ -10035,6 +10035,62 @@ testConnectGetDomainCapabilities(virConnectPtr conn G_GNUC_UNUSED, return virDomainCapsFormat(domCaps); } +static int +testVirDomainAttachDeviceFlags(virDomainPtr domain, + const char *xml, + unsigned int flags G_GNUC_UNUSED) { + + int ret = -1; + virDomainObj *vm; + testDriver *driver; + virDomainDeviceDef *devConf; + + if (!(vm = testDomObjFromDomain(domain))) + return -1; + + driver = domain->conn->privateData; + + if (!(devConf = virDomainDeviceDefParse(xml, vm->def, driver->xmlopt, + NULL, 0))) + goto out; + + VIR_APPEND_ELEMENT(vm->def->hostdevs, vm->def->nhostdevs, + devConf->data.hostdev); + virDomainDeviceDefFree(devConf); + ret = 0; +out: + virDomainObjEndAPI(&vm); + return ret; +} + +static int +testVirDomainAttachDevice(virDomainPtr domain, const char *xml) +{ + return testVirDomainAttachDeviceFlags(domain, xml, 0); +} + +static int +testVirDomainDetachDeviceAlias(virDomainPtr domain, + const char *alias, + unsigned int flags G_GNUC_UNUSED) +{ + virDomainObj *vm; + int size_t; + bool found = false; + + if (!(vm = testDomObjFromDomain(domain))) + return -1; + + for (i = 0; i < vm->def->nhostdevs && !found; i++) { + if (!strcmp(vm->def->hostdevs[i]->info->alias, alias)) { + virDomainHostdevDefFree(vm->def->hostdevs[i]); + VIR_DELETE_ELEMENT(vm->def->hostdevs, i, vm->def->nhostdevs); + found = true; + } + } + virDomainObjEndAPI(&vm); + return found ? 0 : -1; +} /* * Test driver @@ -10058,6 +10114,9 @@ static virHypervisorDriver testHypervisorDriver = { .connectListDomains = testConnectListDomains, /* 0.1.1 */ .connectNumOfDomains = testConnectNumOfDomains, /* 0.1.1 */ .connectListAllDomains = testConnectListAllDomains, /* 0.9.13 */ + .domainAttachDevice = testVirDomainAttachDevice, /* 9.9.0 */ + .domainAttachDeviceFlags = testVirDomainAttachDeviceFlags, /* 9.9.0 */ + .domainDetachDeviceAlias = testVirDomainDetachDeviceAlias, /* 9.9.0 */ .domainCreateXML = testDomainCreateXML, /* 0.1.4 */ .domainCreateXMLWithFiles = testDomainCreateXMLWithFiles, /* 5.7.0 */ .domainLookupByID = testDomainLookupByID, /* 0.1.1 */ -- 2.27.0

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RE: [PATCH] support for hotplug/hotunplug in test hypervisor
by Thanos Makatos 30 Oct '23

30 Oct '23

> -----Original Message----- > From: Daniel P. Berrangé <berrange(a)redhat.com> > Sent: Friday, October 27, 2023 6:13 PM > To: Thanos Makatos <thanos.makatos(a)nutanix.com> > Cc: devel(a)lists.libvirt.org > Subject: Re: [PATCH] support for hotplug/hotunplug in test hypervisor > > On Fri, Oct 27, 2023 at 03:44:13PM +0000, Thanos Makatos wrote: > > Signed-off-by: Thanos Makatos <thanos.makatos(a)nutanix.com> > > --- > > src/test/test_driver.c | 61 > ++++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 59 insertions(+), 2 deletions(-) > > > > diff --git a/src/test/test_driver.c b/src/test/test_driver.c > > index e87d7cfd44..6eda0dcc01 100644 > > --- a/src/test/test_driver.c > > +++ b/src/test/test_driver.c > > @@ -26,8 +26,6 @@ > > #include <unistd.h> > > #include <sys/stat.h> > > #include <libxml/xmlsave.h> > > - > > - > > Unrelated whitespace change. Ack > > > #include "virerror.h" > > #include "datatypes.h" > > #include "test_driver.h" > > @@ -10035,6 +10033,62 @@ > testConnectGetDomainCapabilities(virConnectPtr conn G_GNUC_UNUSED, > > return virDomainCapsFormat(domCaps); > > } > > > > +static int > > +testVirDomainAttachDeviceFlags(virDomainPtr domain, > > + const char *xml, > > + unsigned int flags G_GNUC_UNUSED) { > > + > > + int ret = -1; > > + virDomainObj *vm; > > + testDriver *driver; > > + virDomainDeviceDef *devConf; > > + > > + if (!(vm = testDomObjFromDomain(domain))) > > + return -1; > > + > > + driver = domain->conn->privateData; > > + > > + if (!(devConf = virDomainDeviceDefParse(xml, vm->def, driver->xmlopt, > > + NULL, 0))) > > + goto out; > > + > > + VIR_APPEND_ELEMENT(vm->def->hostdevs, vm->def->nhostdevs, > > + devConf->data.hostdev); > > Aling 'devConf' with the '(' above it Ack > > > + virDomainDeviceDefFree(devConf); > > + ret = 0; > > +out: > > + virDomainObjEndAPI(&vm); > > + return ret; > > +} > > + > > +static int > > +testVirDomainAttachDevice(virDomainPtr domain, const char *xml) > > +{ > > + return testVirDomainAttachDeviceFlags(domain, xml, 0); > > +} > > + > > +static int > > +testVirDomainDetachDeviceAlias(virDomainPtr domain, > > + const char *alias, > > + unsigned int flags __attribute__((unused))) > > Horizontal alignemtn is off, and also needs to be G_GNUC_UNUSED > like the earlier method. Ack > > > +{ > > + virDomainObj *vm; > > + int i; > > size_t for loop iterators please. Ack > > > + bool found = false; > > + > > + if (!(vm = testDomObjFromDomain(domain))) > > + return -1; > > + > > + for (i = 0; i < vm->def->nhostdevs && !found; i++) { > > + if (!strcmp(vm->def->hostdevs[i]->info->alias, alias)) { > > + virDomainHostdevDefFree(vm->def->hostdevs[i]); > > + VIR_DELETE_ELEMENT(vm->def->hostdevs, i, vm->def->nhostdevs); > > + found = true; > > + } > > + } > > + virDomainObjEndAPI(&vm); > > + return found ? 0 : -1; > > +} > > > > /* > > * Test driver > > @@ -10058,6 +10112,9 @@ static virHypervisorDriver testHypervisorDriver = > { > > .connectListDomains = testConnectListDomains, /* 0.1.1 */ > > .connectNumOfDomains = testConnectNumOfDomains, /* 0.1.1 */ > > .connectListAllDomains = testConnectListAllDomains, /* 0.9.13 */ > > + .domainAttachDevice = testVirDomainAttachDevice, /* 9.9.0 */ > > + .domainAttachDeviceFlags = testVirDomainAttachDeviceFlags, /* 9.9.0 */ > > + .domainDetachDeviceAlias = testVirDomainDetachDeviceAlias, /* 9.9.0 */ > > .domainCreateXML = testDomainCreateXML, /* 0.1.4 */ > > .domainCreateXMLWithFiles = testDomainCreateXMLWithFiles, /* 5.7.0 */ > > .domainLookupByID = testDomainLookupByID, /* 0.1.1 */ > > -- > > 2.27.0 > > > > With regards, > Daniel > -- > |: https://urldefense.proofpoint.com/v2/url?u=https- > 3A__berrange.com&d=DwIBaQ&c=s883GpUCOChKOHiocYtGcg&r=XTpYsh5Ps2zJ > vtw6ogtti46atk736SI4vgsJiUKIyDE&m=7tOGBG0mrTLgztzu23pWZjCQpfdKbv7cV > ilnYobvnzJSHk- > m3fVMonE71FEjfJUc&s=MKxz2dbrxpoqVQEKrR1rIHTDNh3TQzk6j9ILpLJO4eI&e > = -o- https://urldefense.proofpoint.com/v2/url?u=https- > 3A__www.flickr.com_photos_dberrange&d=DwIBaQ&c=s883GpUCOChKOHiocYt > Gcg&r=XTpYsh5Ps2zJvtw6ogtti46atk736SI4vgsJiUKIyDE&m=7tOGBG0mrTLgztzu > 23pWZjCQpfdKbv7cVilnYobvnzJSHk-m3fVMonE71FEjfJUc&s=yYyWxbabM- > x_RY69yLXObz2p8wo1OAy4DioA0YScDYc&e= :| > |: https://urldefense.proofpoint.com/v2/url?u=https- > 3A__libvirt.org&d=DwIBaQ&c=s883GpUCOChKOHiocYtGcg&r=XTpYsh5Ps2zJvtw > 6ogtti46atk736SI4vgsJiUKIyDE&m=7tOGBG0mrTLgztzu23pWZjCQpfdKbv7cVilnY > obvnzJSHk- > m3fVMonE71FEjfJUc&s=YVwYpdMFSWcMfQ2sM9QgKFheo9Dxq8s4_sFI0KfGqu > o&e= -o- https://urldefense.proofpoint.com/v2/url?u=https- > 3A__fstop138.berrange.com&d=DwIBaQ&c=s883GpUCOChKOHiocYtGcg&r=XTp > Ysh5Ps2zJvtw6ogtti46atk736SI4vgsJiUKIyDE&m=7tOGBG0mrTLgztzu23pWZjCQ > pfdKbv7cVilnYobvnzJSHk-m3fVMonE71FEjfJUc&s=- > C8ZIdR8IJmdjdVJljDjhjVC4UiJcAeuiWQ-B_dV4wM&e= :| > |: https://urldefense.proofpoint.com/v2/url?u=https-3A__entangle- > 2Dphoto.org&d=DwIBaQ&c=s883GpUCOChKOHiocYtGcg&r=XTpYsh5Ps2zJvtw6o > gtti46atk736SI4vgsJiUKIyDE&m=7tOGBG0mrTLgztzu23pWZjCQpfdKbv7cVilnYob > vnzJSHk- > m3fVMonE71FEjfJUc&s=BgvlBMRgX56LJG0ZSE02GviPHpVTcQ_Nx1N3aEWk9d4 > &e= -o- https://urldefense.proofpoint.com/v2/url?u=https- > 3A__www.instagram.com_dberrange&d=DwIBaQ&c=s883GpUCOChKOHiocYtGc > g&r=XTpYsh5Ps2zJvtw6ogtti46atk736SI4vgsJiUKIyDE&m=7tOGBG0mrTLgztzu23 > pWZjCQpfdKbv7cVilnYobvnzJSHk-m3fVMonE71FEjfJUc&s=g23VsTOOhoOdgm- > cJyiOixKvywYEQXh-L7sRK8YPm90&e= :|

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Entering freeze for libvirt-9.9.0
by Jiri Denemark 30 Oct '23

30 Oct '23

I have just tagged v9.9.0-rc1 in the repository and pushed signed tarballs and source RPMs to https://download.libvirt.org/ Please give the release candidate some testing and in case you find a serious issue which should have a fix in the upcoming release, feel free to reply to this thread to make sure the issue is more visible. If you have not done so yet, please update NEWS.rst to document any significant change you made since the last release. Thanks, Jirka

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[libvirt PATCH 0/4] Update for mailing list move
by Daniel P. Berrangé 30 Oct '23

30 Oct '23

A surprising number of places mention the mailing lists Daniel P. Berrangé (4): src: update log/error messages pointing to old mailing list addr docs: update docs pointing to old mailing list addrs gitpublish: update for new devel mailing list address docs: update search form to use hyperkitty search .gitpublish | 2 +- README.rst | 4 +-- docs/bindings.rst | 2 +- docs/contact.rst | 18 ++++++------- docs/downloads.rst | 2 +- docs/js/main.js | 37 +++++++++++++++++---------- docs/newreposetup.rst | 2 +- docs/securityprocess.rst | 2 +- docs/submitting-patches.rst | 10 ++++---- docs/testapi.rst | 4 +-- src/conf/domain_capabilities.c | 2 +- src/storage_file/storage_file_probe.c | 2 +- src/util/virarch.c | 4 +-- 13 files changed, 51 insertions(+), 40 deletions(-) -- 2.41.0

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[PATCH] support for hotplug/hotunplug in test hypervisor
by Thanos Makatos 27 Oct '23

27 Oct '23

Signed-off-by: Thanos Makatos <thanos.makatos(a)nutanix.com> --- src/test/test_driver.c | 61 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 59 insertions(+), 2 deletions(-) diff --git a/src/test/test_driver.c b/src/test/test_driver.c index e87d7cfd44..6eda0dcc01 100644 --- a/src/test/test_driver.c +++ b/src/test/test_driver.c @@ -26,8 +26,6 @@ #include <unistd.h> #include <sys/stat.h> #include <libxml/xmlsave.h> - - #include "virerror.h" #include "datatypes.h" #include "test_driver.h" @@ -10035,6 +10033,62 @@ testConnectGetDomainCapabilities(virConnectPtr conn G_GNUC_UNUSED, return virDomainCapsFormat(domCaps); } +static int +testVirDomainAttachDeviceFlags(virDomainPtr domain, + const char *xml, + unsigned int flags G_GNUC_UNUSED) { + + int ret = -1; + virDomainObj *vm; + testDriver *driver; + virDomainDeviceDef *devConf; + + if (!(vm = testDomObjFromDomain(domain))) + return -1; + + driver = domain->conn->privateData; + + if (!(devConf = virDomainDeviceDefParse(xml, vm->def, driver->xmlopt, + NULL, 0))) + goto out; + + VIR_APPEND_ELEMENT(vm->def->hostdevs, vm->def->nhostdevs, + devConf->data.hostdev); + virDomainDeviceDefFree(devConf); + ret = 0; +out: + virDomainObjEndAPI(&vm); + return ret; +} + +static int +testVirDomainAttachDevice(virDomainPtr domain, const char *xml) +{ + return testVirDomainAttachDeviceFlags(domain, xml, 0); +} + +static int +testVirDomainDetachDeviceAlias(virDomainPtr domain, + const char *alias, + unsigned int flags __attribute__((unused))) +{ + virDomainObj *vm; + int i; + bool found = false; + + if (!(vm = testDomObjFromDomain(domain))) + return -1; + + for (i = 0; i < vm->def->nhostdevs && !found; i++) { + if (!strcmp(vm->def->hostdevs[i]->info->alias, alias)) { + virDomainHostdevDefFree(vm->def->hostdevs[i]); + VIR_DELETE_ELEMENT(vm->def->hostdevs, i, vm->def->nhostdevs); + found = true; + } + } + virDomainObjEndAPI(&vm); + return found ? 0 : -1; +} /* * Test driver @@ -10058,6 +10112,9 @@ static virHypervisorDriver testHypervisorDriver = { .connectListDomains = testConnectListDomains, /* 0.1.1 */ .connectNumOfDomains = testConnectNumOfDomains, /* 0.1.1 */ .connectListAllDomains = testConnectListAllDomains, /* 0.9.13 */ + .domainAttachDevice = testVirDomainAttachDevice, /* 9.9.0 */ + .domainAttachDeviceFlags = testVirDomainAttachDeviceFlags, /* 9.9.0 */ + .domainDetachDeviceAlias = testVirDomainDetachDeviceAlias, /* 9.9.0 */ .domainCreateXML = testDomainCreateXML, /* 0.1.4 */ .domainCreateXMLWithFiles = testDomainCreateXMLWithFiles, /* 5.7.0 */ .domainLookupByID = testDomainLookupByID, /* 0.1.1 */ -- 2.27.0

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Re: [libvirt] [Qemu-devel] Qemu migration with vhost-user-blk on top of local storage
by Stefan Hajnoczi 27 Oct '23

27 Oct '23

On Wed, Jan 09, 2019 at 06:23:42PM +0800, wuzhouhui wrote: > Hi everyone, > > I'm working qemu with vhost target (e.g. spdk), and I attempt to migrate VM with > 2 local storages. One local storage is a regular file, e.g. /tmp/c74.qcow2, and > the other is a malloc bdev that spdk created. This malloc bdev will exported to > VM via vhost-user-blk. When I execute following command: > > virsh migrate --live --persistent --unsafe --undefinesource --copy-storage-all \ > --p2p --auto-converge --verbose --desturi qemu+tcp://<uri>/system vm0 > > The libvirt reports: > > qemu-2.12.1: error: internal error: unable to execute QEMU command \ > 'nbd-server-add': Cannot find device=drive-virtio-disk1 nor \ > node_name=drive-virtio-disk1 Please post your libvirt domain XML. > Does it means that qemu with spdk on top of local storage don't support migration? > > QEMU: 2.12.1 > SPDK: 18.10 vhost-user-blk bypasses the QEMU block layer, so NBD storage migration at the QEMU level will not work for the vhost-user-blk disk. Stefan

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[libvirt] [PATCH v3] openvswitch: Add new port VLAN mode "dot1q-tunnel"
by luzhipeng＠uniudc.com 27 Oct '23

27 Oct '23

From: ZhiPeng Lu <luzhipeng(a)uniudc.com> Signed-off-by: ZhiPeng Lu <luzhipeng(a)uniudc.com> --- v1->v2: 1. Fix "make syntax-check" failure v2->v3: 1. remove other_config when updating vlan docs/formatnetwork.html.in | 17 +++++++++-------- docs/schemas/networkcommon.rng | 1 + src/conf/netdev_vlan_conf.c | 2 +- src/util/virnetdevopenvswitch.c | 7 +++++++ src/util/virnetdevvlan.h | 1 + 5 files changed, 19 insertions(+), 9 deletions(-) diff --git a/docs/formatnetwork.html.in b/docs/formatnetwork.html.in index 363a72b..3c1ae62 100644 --- a/docs/formatnetwork.html.in +++ b/docs/formatnetwork.html.in @@ -688,16 +688,17 @@ For network connections using Open vSwitch it is also possible - to configure 'native-tagged' and 'native-untagged' VLAN modes + to configure 'native-tagged' and 'native-untagged' and 'dot1q-tunnel' + VLAN modes. Since 1.1.0. This is done with the - optional <code>nativeMode</code> attribute on - the <code><tag></code> subelement: <code>nativeMode</code> - may be set to 'tagged' or 'untagged'. The <code>id</code> - attribute of the <code><tag></code> subelement - containing <code>nativeMode</code> sets which VLAN is considered - to be the "native" VLAN for this interface, and + optional <code>nativeMode</code> attribute on the + <code><tag></code> subelement: <code>nativeMode</code> + may be set to 'tagged' or 'untagged' or 'dot1q-tunnel'. + The <code>id</code> attribute of the <code><tag></code> + subelement containing <code>nativeMode</code> sets which VLAN is + considered to be the "native" VLAN for this interface, and the <code>nativeMode</code> attribute determines whether or not - traffic for that VLAN will be tagged. + traffic for that VLAN will be tagged or QinQ. <code><vlan></code> elements can also be specified in diff --git a/docs/schemas/networkcommon.rng b/docs/schemas/networkcommon.rng index 2699555..11c48ff 100644 --- a/docs/schemas/networkcommon.rng +++ b/docs/schemas/networkcommon.rng @@ -223,6 +223,7 @@ <choice> <value>tagged</value> <value>untagged</value> + <value>dot1q-tunnel</value> </choice> </attribute> </optional> diff --git a/src/conf/netdev_vlan_conf.c b/src/conf/netdev_vlan_conf.c index dff49c6..79710d9 100644 --- a/src/conf/netdev_vlan_conf.c +++ b/src/conf/netdev_vlan_conf.c @@ -29,7 +29,7 @@ #define VIR_FROM_THIS VIR_FROM_NONE VIR_ENUM_IMPL(virNativeVlanMode, VIR_NATIVE_VLAN_MODE_LAST, - "default", "tagged", "untagged") + "default", "tagged", "untagged", "dot1q-tunnel") int virNetDevVlanParse(xmlNodePtr node, xmlXPathContextPtr ctxt, virNetDevVlanPtr def) diff --git a/src/util/virnetdevopenvswitch.c b/src/util/virnetdevopenvswitch.c index 8fe06fd..9fec30b 100644 --- a/src/util/virnetdevopenvswitch.c +++ b/src/util/virnetdevopenvswitch.c @@ -91,6 +91,11 @@ virNetDevOpenvswitchConstructVlans(virCommandPtr cmd, virNetDevVlanPtr virtVlan) virCommandAddArg(cmd, "vlan_mode=native-untagged"); virCommandAddArgFormat(cmd, "tag=%d", virtVlan->nativeTag); break; + case VIR_NATIVE_VLAN_MODE_DOT1Q_TUNNEL: + virCommandAddArg(cmd, "vlan_mode=dot1q-tunnel"); + virCommandAddArg(cmd, "other_config:qinq-ethtype=802.1q"); + virCommandAddArgFormat(cmd, "tag=%d", virtVlan->nativeTag); + break; case VIR_NATIVE_VLAN_MODE_DEFAULT: default: break; @@ -504,6 +509,8 @@ int virNetDevOpenvswitchUpdateVlan(const char *ifname, "--", "--if-exists", "clear", "Port", ifname, "tag", "--", "--if-exists", "clear", "Port", ifname, "trunk", "--", "--if-exists", "clear", "Port", ifname, "vlan_mode", + "--", "--if-exists", "remove", "Port", ifname, "other_config", + "qinq-ethtype", NULL, "--", "--if-exists", "set", "Port", ifname, NULL); if (virNetDevOpenvswitchConstructVlans(cmd, virtVlan) < 0) diff --git a/src/util/virnetdevvlan.h b/src/util/virnetdevvlan.h index be85f59..0667f9d 100644 --- a/src/util/virnetdevvlan.h +++ b/src/util/virnetdevvlan.h @@ -29,6 +29,7 @@ typedef enum { VIR_NATIVE_VLAN_MODE_DEFAULT = 0, VIR_NATIVE_VLAN_MODE_TAGGED, VIR_NATIVE_VLAN_MODE_UNTAGGED, + VIR_NATIVE_VLAN_MODE_DOT1Q_TUNNEL, VIR_NATIVE_VLAN_MODE_LAST } virNativeVlanMode; -- 1.8.3.1

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[libvirt] [PATCH] Fix compile error for stable 1.2.9
by Yang hongyang 27 Oct '23

27 Oct '23

Seems a backport miss. An extra member is passed to struct virLXCBasicMountInfo. Signed-off-by: Yang hongyang <hongyang.yang(a)easystack.cn> --- src/lxc/lxc_container.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index 28dabec..1c65fa9 100644 --- a/src/lxc/lxc_container.c +++ b/src/lxc/lxc_container.c @@ -760,7 +760,7 @@ typedef struct { static const virLXCBasicMountInfo lxcBasicMounts[] = { { "proc", "/proc", "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, false, false }, - { "/proc/sys", "/proc/sys", NULL, MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, false, false, false }, + { "/proc/sys", "/proc/sys", NULL, MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, false, false }, { "sysfs", "/sys", "sysfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, false, false }, { "securityfs", "/sys/kernel/security", "securityfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, true, true }, #if WITH_SELINUX -- 1.7.1

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[libvirt] [PATCH] web docs -- macvtap mode explanation
by Stefan Berger 27 Oct '23

27 Oct '23

This adds more information about the different macvtap device modes. Regards, Stefan

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[libvirt] Supporting vhost-net and macvtap in libvirt for QEMU
by Anthony Liguori 27 Oct '23

27 Oct '23

Disclaimer: I am neither an SR-IOV nor a vhost-net expert, but I've CC'd people that are who can throw tomatoes at me for getting bits wrong :-) I wanted to start a discussion about supporting vhost-net in libvirt. vhost-net has not yet been merged into qemu but I expect it will be soon so it's a good time to start this discussion. There are two modes worth supporting for vhost-net in libvirt. The first mode is where vhost-net backs to a tun/tap device. This is behaves in very much the same way that -net tap behaves in qemu today. Basically, the difference is that the virtio backend is in the kernel instead of in qemu so there should be some performance improvement. Current, libvirt invokes qemu with -net tap,fd=X where X is an already open fd to a tun/tap device. I suspect that after we merge vhost-net, libvirt could support vhost-net in this mode by just doing -net vhost,fd=X. I think the only real question for libvirt is whether to provide a user visible switch to use vhost or to just always use vhost when it's available and it makes sense. Personally, I think the later makes sense. The more interesting invocation of vhost-net though is one where the vhost-net device backs directly to a physical network card. In this mode, vhost should get considerably better performance than the current implementation. I don't know the syntax yet, but I think it's reasonable to assume that it will look something like -net tap,dev=eth0. The effect will be that eth0 is dedicated to the guest. On most modern systems, there is a small number of network devices so this model is not all that useful except when dealing with SR-IOV adapters. In that case, each physical device can be exposed as many virtual devices (VFs). There are a few restrictions here though. The biggest is that currently, you can only change the number of VFs by reloading a kernel module so it's really a parameter that must be set at startup time. I think there are a few ways libvirt could support vhost-net in this second mode. The simplest would be to introduce a new tag similar to <source network='br0'>. In fact, if you probed the device type for the network parameter, you could probably do something like <source network='eth0'> and have it Just Work. Another model would be to have libvirt see an SR-IOV adapter as a network pool whereas it handled all of the VF management. Considering how inflexible SR-IOV is today, I'm not sure whether this is the best model. Has anyone put any more thought into this problem or how this should be modeled in libvirt? Michael, could you share your current thinking for -net syntax? -- Regards, Anthony Liguori

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