Over root-squashing nfs, when virFileOperation() is called as uid==0,
it may fail with EACCES, but also with EPERM, due to
virFileOperationNoFork()'s failed attemp to chown a writable file.
qemudDomainSaveFlag() should expect this case, too.
qemudOpenAsUID is intended to open a file with the credentials of a
specified uid. Current implementation fails if the file is accessible to
one of uid's groups but not owned by uid.
This patch replaces the supplementary group list that the child process
inherited from libvirtd with the default group list of uid.
Explicitly raising a nice error in the case user tries to migrate a
guest with assigned host devices is much better than waiting for a
mysterious error with no clue for the reason.
This is from a bug report and conversation on IRC where Soren reported that while a filter update is occurring on one or more VMs (due to a rule having been edited for example), a deadlock can occur when a VM referencing a filter is started.
The problem is caused by the two locking sequences of
qemu driver, qemu domain, filter # for the VM start operation
filter, qemu_driver, qemu_domain # for the filter update operation
that obviously don't lock in the same order. The problem is the 2nd lock sequence. Here the qemu_driver lock is being grabbed in qemu_driver:qemudVMFilterRebuild()
The following solution is based on the idea of trying to re-arrange the 2nd sequence of locks as follows:
qemu_driver, filter, qemu_driver, qemu_domain
and making the qemu driver recursively lockable so that a second lock can occur, this would then lead to the following net-locking sequence
qemu_driver, filter, qemu_domain
where the 2nd qemu_driver lock has been ( logically ) eliminated.
The 2nd part of the idea is that the sequence of locks (filter, qemu_domain) and (qemu_domain, filter) becomes interchangeable if all code paths where filter AND qemu_domain are locked have a preceding qemu_domain lock that basically blocks their concurrent execution
So, the following code paths exist towards qemu_driver:qemudVMFilterRebuild where we now want to put a qemu_driver lock in front of the filter lock.
-> nwfilterUndefine() [ locks the filter ]
-> virNWFilterTestUnassignDef()
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
-> nwfilterDefine()
-> virNWFilterPoolAssignDef() [ locks the filter ]
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
-> nwfilterDriverReload()
-> virNWFilterPoolLoadAllConfigs()
->virNWFilterPoolObjLoad()
-> virNWFilterPoolAssignDef() [ locks the filter ]
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
-> nwfilterDriverStartup()
-> virNWFilterPoolLoadAllConfigs()
->virNWFilterPoolObjLoad()
-> virNWFilterPoolAssignDef() [ locks the filter ]
-> virNWFilterTriggerVMFilterRebuild()
-> qemudVMFilterRebuild()
Qemu is not the only driver using the nwfilter driver, but also the UML driver calls into it. Therefore qemuVMFilterRebuild() can be exchanged with umlVMFilterRebuild() along with the driver lock of qemu_driver that can now be a uml_driver. Further, since UML and Qemu domains can be running on the same machine, the triggering of a rebuild of the filter can touch both types of drivers and their domains.
In the patch below I am now extending each nwfilter callback driver with functions for locking and unlocking the (VM) driver (UML, QEMU) and introduce new functions for locking all registered callback drivers and unlocking them. Then I am distributing the lock-all-cbdrivers/unlock-all-cbdrivers call into the above call paths. The last shown callpath starting with nwfilterDriverStart() is problematic since it is initialize before the Qemu and UML drives are and thus a lock in the path would result in a NULL pointer attempted to be locked -- the call to virNWFilterTriggerVMFilterRebuild() is never called, so we never lock either the qemu_driver or the uml_driver in that path. Therefore, only the first 3 paths now receive calls to lock and unlock all callback drivers. Now that the locks are distributed where it matters I can remove the qemu_driver and uml_driver lock from qemudVMFilterRebuild() and umlVMFilterRebuild() and not requiring the recursive locks.
For now I want to put this out as an RFC patch. I have tested it by 'stretching' the critical section after the define/undefine functions each lock the filter so I can (easily) concurrently execute another VM operation (suspend,start). That code is in this patch and if you want you can de-activate it. It seems to work ok and operations are being blocked while the update is being done.
I still also want to verify the other assumption above that locking filter and qemu_domain always has a preceding qemu_driver lock.
Adding parsing code for memory tunables in the domain xml file
also change the internal define structures used for domain memory
informations
Adds a new specific test
Public api to set/get memory tunables supported by the hypervisors.
dv:
* some cleanups in libvirt.c
* adding extra checks in libvirt.c new entry points
v4:
* Move exporting public API to this patch
* Add unsigned int flags to the public api for future extensions
v3:
* Add domainGetMemoryParamters and NULL in all the driver interface
v2:
* Initialize domainSetMemoryParameters to NULL in all the driver
interface structure.
Other drivers will need this same functionality, so move it to up to
conf/domain_conf.c and give it a more general name.
Signed-off-by: Soren Hansen <soren@linux2go.dk>
The current version of the qemu managed save implementation
is subject to a race where the domain shuts down between
the time that we start the command and the time that we
actually try to do the save. Close this race by making
qemuDomainSaveFlags() expect both the driver and the passed-in
vm object to be locked before executing.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
When reconnecting to existing VMs, we re-reserved only those PCI
addresses which were explicitly mentioned in domain XML. Since some
addresses are always reserved (e.g., 0:0:0 and 0:0:1), we need to handle
those too.
Also all this should only be done if device flag is supported by qemu.
In this patch I am extending and fixing the nwfilter module's reload support to stop all ongoing threads (for learning IP addresses of interfaces) and rebuild the filtering rules of all interfaces of all VMs when libvirt is started. Now libvirtd rebuilds the filters upon the SIGHUP signal and libvirtd restart.
About the patch: The nwfilter functions require a virConnectPtr. Therefore I am opening a connection in qemudStartup, which later on needs to be closed outside where the driver lock is held since otherwise it ends up in a deadlock due to virConnectClose() trying to lock the driver as well.
I have tested this now for a while with several machines running and needing the IP address learner thread(s). The rebuilding of the firewall rules seems to work fine following libvirtd restart or a SIGHUP. Also the termination of libvirtd worked fine.
Since the qemu process is running as qemu:qemu, it can't actually
look at the unix socket in /var/run/libvirt/qemu which is owned by
root and has permission 700. Move the unix socket to
/var/lib/libvirt/qemu, which is already owned by qemu:qemu.
Thanks to Justin Clift for test this out for me.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
The problem is that on the source of the migration, libvirtd
is responsible for creating the unix socket over which the data
will flow. Since libvirtd is running as root, this file will
be created as root. When the qemu process running as qemu:qemu
goes to access the unix file to write data to it, it will get
permission denied and fail. Make sure to change the owner
of the unix file to qemu:qemu.
Thanks to Justin Clift for testing this patch out for me.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Basically a followup of the previous patch about balloon desactivation
if desactivated, to not ask for balloon information to qemu as we will
just get an error back.
This can make a huge difference in the time needed for domain
information or list when a machine is loaded, and balloon has been
desactivated in the guests.
* src/qemu/qemu_driver.c: do not get the balloon info if the balloon
suppor is disabled
device_del command is not synchronous for PCI devices, it merely asks
the guest to release the device and returns. If the host wants to use
that device before the guest actually releases it, we are in big
trouble. To avoid this, we already added a loop which waits up to 10
seconds until the device is actually released before we do anything else
with that device. But we only added this loop for managed PCI devices
before we try reattach them back to the host.
However, we need to wait even for non-managed devices. We don't reattach
them automatically, but we still want to prevent the host from using it.
This was revealed thanks to sVirt: when we relabel sysfs files
corresponding to the PCI device before the guest finished releasing the
device, qemu is no longer allowed to access those files and if it wants
(as a result of guest's request) to write anything to them, it just
exits, which kills the guest.
This is not a proper fix and needs some further work both on libvirt and
qemu side in the future.
If detecting the FLR flag of a pci device fails, then we
could run into the situation of trying to close a file
descriptor twice, once in pciInitDevice() and once in pciFreeDevice().
Fix that by removing the pciCloseConfig() in pciInitDevice() and
just letting pciFreeDevice() handle it.
Thanks to Chris Wright for pointing out this problem.
While we are at it, fix an error check. While it would actually
work as-is (since success returns 0), it's still more clear to
check for < 0 (as the rest of the code does).
Signed-off-by: Chris Lalancette <clalance@redhat.com>
There is actually a difference between the character device type (serial,
parallel, channel, ...) and the target type (virtio, guestfwd). Currently
they are awkwardly conflated.
Start to pull them apart by renaming targetType -> deviceType. This is
an entirely mechanical change.
Signed-off-by: Cole Robinson <crobinso@redhat.com>
When doing a PCI secondary bus reset, we must be sure that there are no
active devices on the same bus segment. The active device tracking is
designed to only track host devices that are active in use by guests.
This ignores host devices that are actively in use by the host. So the
current logic will reset host devices.
Switch this logic around and allow sbus reset when we are assigning all
devices behind a bridge to the same guest at guest startup or as a result
of a single attach-device command.
* src/util/pci.h: change signature of pciResetDevice to add an
inactive devices list
* src/qemu/qemu_driver.c src/xen/xen_driver.c: use (or not) the new
functionality of pciResetDevice() depending on the place of use
* src/util/pci.c: implement the interface and logic changes
- src/qemu/qemu_driver.c: Eliminate code duplication by using the new
helpers qemuPrepareHostdevPCIDevices and qemuDomainReAttachHostdevDevices.
This reduces the number of open coded calls to pciResetDevice.
- src/qemu/qemu_driver.c: These new helpers take hostdev list and count
directly rather than getting them indirectly from domain definition.
This will allow reuse for the attach-device case.
- src/qemu/qemu_driver.c: Update qemuGetPciHostDeviceList to take a
hostdev list and count directly, rather than getting this indirectly
from domain definition. This will allow reuse for the attach-device case.
Thanks to DV for knocking together the Relax-NG changes
quickly for me.
Changes since v1:
- Change the domain.rng to correspond to the new schema
- Don't allocate caps->ns in testQemuCapsInit since it is a static table
Changes since v2:
- Change domain.rng to add restrictions on allowed environment names
Changes since v3:
- Remove a bogus comment in the tests
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Implement the qemu driver's virDomainQemuMonitorCommand
and hook it into the API entry point.
Changes since v1:
- Rename the (external) qemuMonitorCommand to qemuDomainMonitorCommand
- Add virCheckFlags to qemuDomainMonitorCommand
Changes since v2:
- Drop ATTRIBUTE_UNUSED from the flags
Changes since v3:
- Add a flag to priv so we only print out monitor command warning once. Note
that this has not been plumbed into qemuDomainObjPrivateXMLFormat or
qemuDomainObjPrivateXMLParse, which means that if you run a monitor command,
restart libvirtd, and then run another monitor command, you may get an
an erroneous VIR_INFO. It's a pretty minor matter, and I didn't think it
warranted the additional code.
- Add BeginJob/EndJob calls around EnterMonitor/ExitMonitor
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Add the library entry point for the new virDomainQemuMonitorCommand()
entry point. Because this is not part of the "normal" libvirt API,
it gets its own header file, library file, and will eventually
get its own over-the-wire protocol later in the series.
Changes since v1:
- Go back to using the virDriver table for qemuDomainMonitorCommand, due to
linking issues
- Added versioning information to the libvirt-qemu.so
Changes since v2:
- None
Changes since v3:
- Add LGPL header to libvirt-qemu.c
- Make virLibConnError and virLibDomainError macros instead of function calls
Changes since v4:
- Move exported symbols to libvirt_qemu.syms
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Implement the qemu hooks for XML namespace data. This
allows us to specify a qemu XML namespace, and then
specify:
<qemu:commandline>
<qemu:arg value='arg'/>
<qemu:env name='name' value='value'/>
</qemu:commandline>
In the domain XML.
Changes since v1:
- Change the <qemu:arg>arg</qemu:arg> XML to <qemu:arg value='arg'/> XML
- Fix up some memory leaks in qemuDomainDefNamespaceParse
- Rename num_extra and extra to num_args and args, respectively
- Fixed up some error messages
- Make sure to escape user-provided data in qemuDomainDefNamespaceFormatXML
Changes since v2:
- Add checking to ensure environment variable names are valid
- Invert the logic in qemuDomainDefNamespaceFormatXML to return early
Changes since v3:
- Change strspn() to c_isalpha() check of first letter of environment variable
Signed-off-by: Chris Lalancette <clalance@redhat.com>
virFileOperation previously returned 0 on success, or the value of
errno on failure. Although there are other functions in libvirt that
use this convention, the preferred (and more common) convention is to
return 0 on success and -errno (or simply -1 in some cases) on
failure. This way the check for failure is always (ret < 0).
* src/util/util.c - change virFileOperation and virFileOperationNoFork to
return -errno on failure.
* src/storage/storage_backend.c, src/qemu/qemu_driver.c
- change the hook functions passed to virFileOperation to return
-errno on failure.
To allow compatibility with older QEMU PCI device slot assignment
it is necessary to explicitly track the balloon device in the
XML. This introduces a new device
<memballoon model='virtio|xen'/>
It can also have a PCI address, auto-assigned if necessary.
The memballoon will be automatically added to all Xen and QEMU
guests by default.
* docs/schemas/domain.rng: Add <memballoon> element
* src/conf/domain_conf.c, src/conf/domain_conf.h: parsing
and formatting for memballoon device. Always add a memory
balloon device to Xen/QEMU if none exists in XML
* src/libvirt_private.syms: Export memballoon model APIs
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Honour the
PCI device address in memory balloon device
* tests/*: Update to test new functionality
The VIR_ERR_NO_SUPPORT refers to an API which is not implemented.
There is a separate VIR_ERR_CONFIG_UNSUPPORTED for XML config
options that are not available with the current hypervisor.
* src/qemu/qemu_conf.c, src/qemu/qemu_driver.c: Remove
many VIR_ERR_NO_SUPPORT replace with VIR_ERR_CONFIG_UNSUPPORTED
If you try to execute two concurrent migrations p2p
from A->B and B->A, the two libvirtd's will deadlock
trying to perform the migrations. The reason for this is
that in p2p migration, the libvirtd's are responsible for
making the RPC Prepare, Migrate, and Finish calls. However,
they are currently holding the driver lock while doing so,
which basically guarantees deadlock in this scenario.
This patch fixes the situation by adding
qemuDomainObjEnterRemoteWithDriver and
qemuDomainObjExitRemoteWithDriver helper methods. The Enter
take an additional object reference, then drops both the
domain object lock and the driver lock. The Exit takes
both the driver and domain object lock, then drops the
reference. Adding calls to these Enter and Exit helpers
around remote calls in the various migration methods
seems to fix the problem for me in testing.
This should make the situation safe. The additional domain
object reference ensures that the domain object won't disappear
while this operation is happening. The BeginJob that is called
inside of qemudDomainMigratePerform ensures that we can't execute a
second migrate (or shutdown, or save, etc) job while the
migration is active. Finally, the additional check on the state
of the vm after we reacquire the locks ensures that we can't
be surprised by an external event (domain crash, etc).
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Record a default driver name/type in capabilities struct. Use this
when parsing disks if value is not set in XML config.
* src/conf/capabilities.h: Record default driver name/type for disks
* src/conf/domain_conf.c: Fallback to default driver name/type
when parsing disks
* src/qemu/qemu_driver.c: Set default driver name/type to raw
Disk format probing is now disabled by default. A new config
option in /etc/qemu/qemu.conf will re-enable it for existing
deployments where this causes trouble
The implementation of security driver callbacks often needs
to access the security driver object. Currently only a handful
of callbacks include the driver object as a parameter. Later
patches require this is many more places.
* src/qemu/qemu_driver.c: Pass in the security driver object
to all callbacks
* src/qemu/qemu_security_dac.c, src/qemu/qemu_security_stacked.c,
src/security/security_apparmor.c, src/security/security_driver.h,
src/security/security_selinux.c: Add a virSecurityDriverPtr
param to all security callbacks
Update the QEMU cgroups code, QEMU DAC security driver, SELinux
and AppArmour security drivers over to use the shared helper API
virDomainDiskDefForeachPath().
* src/qemu/qemu_driver.c, src/qemu/qemu_security_dac.c,
src/security/security_selinux.c, src/security/virt-aa-helper.c:
Convert over to use virDomainDiskDefForeachPath()
Require the disk image to be passed into virStorageFileGetMetadata.
If this is set to VIR_STORAGE_FILE_AUTO, then the format will be
resolved using probing. This makes it easier to control when
probing will be used
* src/qemu/qemu_driver.c, src/qemu/qemu_security_dac.c,
src/security/security_selinux.c, src/security/virt-aa-helper.c:
Set VIR_STORAGE_FILE_AUTO when calling virStorageFileGetMetadata.
* src/storage/storage_backend_fs.c: Probe for disk format before
calling virStorageFileGetMetadata.
* src/util/storage_file.h, src/util/storage_file.c: Remove format
from virStorageFileMeta struct & require it to be passed into
method.
* src/qemu/qemu_driver.c (qemuConnectMonitor): Correct erroneous
parenthesization in two expressions. Without this fix, failure
to set or clear SELinux security context in the monitor would go
undiagnosed. Also correct a diagnostic and split some long lines.
Make sure to *not* call qemuDomainPCIAddressReleaseAddr if
QEMUD_CMD_FLAG_DEVICE is *not* set (for older qemu). This
prevents a crash when trying to do device detachment from
a qemu guest.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
In the current libvirt PCI code, there is no checking whether
a PCI device is in use by a guest when doing node device
detach or reattach. This causes problems when a device is
assigned to a guest, and the administrator starts issuing
nodedevice commands. Make it so that we check the list
of active devices when trying to detach/reattach, and only
allow the operation if the device is not assigned to a guest.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
This code was just recently added (by me) and didn't account for the
fact that stdin_path is sometimes NULL. If it's NULL, and
SetSecurityAllLabel fails, a segfault would result.
When the saved domain image is on an NFS share, at least some part of
domainSetSecurityAllLabel will fail (for example, selinux labels can't
be modified). To allow domain restore to still work in this case, just
ignore the errors.
