[libvirt] Supporting vhost-net and macvtap in libvirt for QEMU
by Anthony Liguori
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
6 months, 2 weeks
[libvirt] [PATCH 0/4] Multiple problems with saving to block devices
by Daniel P. Berrange
This patch series makes it possible to save to a block device,
instead of a plain file. There were multiple problems
- WHen save failed, we might de-reference a NULL pointer
- When save failed, we unlinked the device node !!
- The approach of using >> to append, doesn't work with block devices
- CGroups was blocking QEMU access to the block device when enabled
One remaining problem is not in libvirt, but rather QEMU. The QEMU
exec: based migration often fails to detect failure of the command
and will thus hang forever attempting a migration that'll never
succeed! Fortunately you can now work around this in libvirt using
the virsh domjobabort command
11 years, 1 month
[libvirt] libvirt(-java): virDomainMigrateSetMaxDowntime
by Thomas Treutner
Hi,
I'm facing some troubles with virDomainMigrate &
virDomainMigrateSetMaxDowntime. The core problem is that KVM's default
value for the maximum allowed downtime is 30ms (max_downtime in
migration.c, it's nanoseconds there; 0.12.3) which is too low for my VMs
when they're busy (~50% CPU util and above). Migrations then take
literally forever, I had to abort them after 15 minutes or so. I'm using
GBit Ethernet, so plenty bandwidth should be available. Increasing the
allowed downtime to 50ms seems to help, but I have not tested situations
where the VM is completely utilized. Anyways, the default value is too
low for me, so I tried virDomainMigrateSetMaxDowntime resp. the Java
wrapper function.
Here I'm facing a problem I can overcome only with a quite crude hack:
org.libvirt.Domain.migrate(..) blocks until the migration is done, which
is of course reasonable. So I tried calling migrateSetMaxDowntime(..)
before migrating, causing an error:
"Requested operation is not valid: domain is not being migrated"
This tells me that calling migrateSetMaxDowntime is only allowed during
migrations. As I'm migrating VMs automatically and without any user
intervention I'd need to create some glue code that runs in an extra
thread, waiting "some time" hoping that the migration was kicked off in
the main thread yet and then calling migrateSetMaxDowntime. I'd like to
avoid such quirks in the long run, if possible.
So my question: Would it be possible to extend the migrate() method
resp. virDomainMigrate() function with an optional maxDowntime parameter
that is passed down as QEMU_JOB_SIGNAL_MIGRATE_DOWNTIME so that
qemuDomainWaitForMigrationComplete would set the value? Or are there
easier ways?
Thanks and regards,
-t
12 years, 7 months
[libvirt] snapshots += domain description?
by Philipp Hahn
Hello,
I just encountered a problem with the current snapshot implementation for
qemu/kvm: To revert back to a snapshot, the domain description must closely
match the domain description when the snapshot was created. If the ram-size
doesn't match or the VM now contains fewer CPUs or contains additional disks,
kvm will either not load the snapshot or the machine will be broken
afterwarts.
Is this a known problem?
Without looking into the implementation details I think saving the full domain
description instead of just a reference to the domain uuid as part of the
snapshot description would work better. Or am I supposed to save the domain
description myself in addition the the data saved
in /var/lib/libvirt/qemu/snapshot/$DOMAIN_NAME/$SNAPSHOT_NAME.xml. I think
this is very important feature, because when you - for example - notice that
you need additional disk space and would like to include an additional block
device, this is your ideal time to take a snapshot you can revert to when you
do something wrong.
Looking at VMware I see that reverting a VM there will not only revert the
disks and ram back to the saved state, but also the description including
name, ram size, etc.
Any comment or advise is appreciated.
Sincerely
Philipp Hahn
--
Philipp Hahn Open Source Software Engineer hahn(a)univention.de
Univention GmbH Linux for Your Business fon: +49 421 22 232- 0
Mary-Somerville-Str.1 28359 Bremen fax: +49 421 22 232-99
http://www.univention.de
12 years, 9 months
[libvirt] (how much) support for kqemu domain
by John Lumby
I am wondering about the extent to which "old" qemu-0.11.1 and kqemu-1.4.0 are supported by virt-manager.
I see I can specify --virt-type=kqemu on virt-install and it remembers domain type='kqemu', and does things such as refusing to start the vm if the kqemu kernel mod not loaded, but it seems it does not tack on the
-enable-kqemu -kernel-kqemu
options on to the qemu command line. There is really not much point in trying to start a qemu-based vm with neither hardware kvm nor kqemu ...
I can work around it with an override script to intercept the qemu command, but does anyone think virt-manager ought to do this for me?
John Lumby
_________________________________________________________________
12 years, 11 months
[libvirt] [PATCH V2] xen: check if device is assigned to guest before reattaching
by Yufang Zhang
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=664059
This is the version2 patch for BZ#664059. Reattaching pci device back to
host without destroying guest or detaching device from guest would cause
host to crash. This patch adds a check before doing device reattach. If
the device is being assigned to guest, libvirt refuses to reattach device
to host. The patch only works for Xen, for it just checks xenstore to get
pci device information.
Signed-off-by: Yufang Zhang <yuzhang(a)redhat.com>
---
src/xen/xen_driver.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 67 insertions(+), 0 deletions(-)
diff --git a/src/xen/xen_driver.c b/src/xen/xen_driver.c
index 4c11b11..318bb6a 100644
--- a/src/xen/xen_driver.c
+++ b/src/xen/xen_driver.c
@@ -1891,11 +1891,70 @@ out:
}
static int
+xenUnifiedNodeDeviceAssignedDomainId (virNodeDevicePtr dev)
+{
+ int numdomains;
+ int ret = -1, i;
+ int *ids = NULL;
+ char *bdf = NULL;
+ char *xref = NULL;
+ unsigned int domain, bus, slot, function;
+ virConnectPtr conn = dev->conn;
+ xenUnifiedPrivatePtr priv = conn->privateData;
+
+ /* Get active domains */
+ numdomains = xenUnifiedNumOfDomains(conn);
+ if (numdomains < 0) {
+ return ret;
+ }
+ if (numdomains > 0){
+ if (VIR_ALLOC_N(ids, numdomains) < 0){
+ virReportOOMError();
+ goto out;
+ }
+ if ((numdomains = xenUnifiedListDomains(conn, &ids[0], numdomains)) < 0){
+ goto out;
+ }
+ }
+
+ /* Get pci bdf */
+ if (xenUnifiedNodeDeviceGetPciInfo(dev, &domain, &bus, &slot, &function) < 0)
+ goto out;
+
+ if (virAsprintf(&bdf, "%04x:%02x:%02x.%0x",
+ domain, bus, slot, function) < 0) {
+ virReportOOMError();
+ goto out;
+ }
+
+ /* Check if bdf is assigned to one of active domains */
+ for (i = 0; i < numdomains; i++ ){
+ xenUnifiedLock(priv);
+ xref = xenStoreDomainGetPCIID(conn, ids[i], bdf);
+ xenUnifiedUnlock(priv);
+ if (xref == NULL)
+ continue;
+ else {
+ ret = ids[i];
+ break;
+ }
+ }
+
+ VIR_FREE(xref);
+ VIR_FREE(bdf);
+out:
+ VIR_FREE(ids);
+
+ return ret;
+}
+
+static int
xenUnifiedNodeDeviceReAttach (virNodeDevicePtr dev)
{
pciDevice *pci;
unsigned domain, bus, slot, function;
int ret = -1;
+ int domid;
if (xenUnifiedNodeDeviceGetPciInfo(dev, &domain, &bus, &slot, &function) < 0)
return -1;
@@ -1904,6 +1963,14 @@ xenUnifiedNodeDeviceReAttach (virNodeDevicePtr dev)
if (!pci)
return -1;
+ /* Check if device is assigned to an active guest */
+ if ((domid = xenUnifiedNodeDeviceAssignedDomainId(dev)) >= 0){
+ xenUnifiedError(VIR_ERR_INTERNAL_ERROR,
+ _("Device %s has been assigned to guest %d"),
+ dev->name, domid);
+ goto out;
+ }
+
if (pciReAttachDevice(pci, NULL) < 0)
goto out;
--
1.7.3.4
13 years
[libvirt] [PATCH 0/3] PHYP: Adding network management support
by Eduardo Otubo
This is a series of 3 patches to add network management support for
pHyp driver.
Eduardo Otubo (3):
PHYP: Separating UUID functions in another file
PHYP: Adding basic network functions
PHYP: create, destroy and other network functions
po/POTFILES.in | 1 +
src/Makefile.am | 3 +-
src/phyp/phyp_driver.c | 1066 +++++++++++++++++++++++++++---------------------
src/phyp/phyp_driver.h | 43 ++-
src/phyp/phyp_uuid.c | 834 +++++++++++++++++++++++++++++++++++++
src/phyp/phyp_uuid.h | 44 ++
6 files changed, 1520 insertions(+), 471 deletions(-)
create mode 100644 src/phyp/phyp_uuid.c
create mode 100644 src/phyp/phyp_uuid.h
13 years
[libvirt] cont command failing via JSON monitor on restore
by Jim Fehlig
libvirt 0.8.7
qemu 0.13
I'm looking into a problem with qemu save/restore via JSON monitor. On
restore, the vm is left in a paused state with following error returned
for 'cont' command
An incoming migration is expected before this command can be executed
I was trying to debug the issue in gdb, but stepping through the code
introduces enough delay between qemudStartVMDaemon() and doStartCPUs()
that the latter succeeds. Any suggestions on how to determine when it
is safe to call doStartCPUs() to prevent the above error? I don't see
this issue with the text monitor btw.
Thanks,
Jim
13 years, 1 month
[libvirt] xen:/// vs. xen://FQDN/ vs xen+unix:/// discrepancy
by Philipp Hahn
Hello,
I regularly observe the problem, that depending on the libvirt-URL I get
different information:
root@xen4# virsh -c xen://xen4.domain.name/ list
Id Name State
----------------------------------
root@xen4# virsh -c xen:/// list
Id Name State
----------------------------------
0 Domain-0 running
1 dos4 idle
root@xen4# virsh -c xen+unix:/// list
Id Name State
----------------------------------
root@xen4# xm li
Name ID Mem VCPUs State
Time(s)
Domain-0 0 2044 2 r----- 419.7
dos4 1 4 1 -b---- 33.4
Has somebody observed the same problem and/or can give me any advise on where
to look for the problem?
I'm running a Debian-Lenny based OS with libvirt-0.8.2 on Xen-3.4.3 with a
2.6.32 kernel.
Sincerely
Philipp Hahn
--
Philipp Hahn Open Source Software Engineer hahn(a)univention.de
Univention GmbH Linux for Your Business fon: +49 421 22 232- 0
Mary-Somerville-Str.1 28359 Bremen fax: +49 421 22 232-99
http://www.univention.de
13 years, 1 month
