I've encountered the following bug, but only on Gentoo with
systemd and CGroupsV2. I've started an LXC container successfully
but destroying it reported the following error:
error: Failed to destroy domain 'amd64'
error: internal error: failed to get cgroup backend for 'pathOfController'
Debugging showed, that CGroup hierarchy is full of surprises:
/sys/fs/cgroup/machine.slice/machine-lxc\x2d861\x2damd64.scope/
└── libvirt
├── dev-hugepages.mount
├── dev-mqueue.mount
├── init.scope
├── sys-fs-fuse-connections.mount
├── sys-kernel-config.mount
├── sys-kernel-debug.mount
├── sys-kernel-tracing.mount
├── system.slice
│ ├── console-getty.service
│ ├── dbus.service
│ ├── system-getty.slice
│ ├── system-modprobe.slice
│ ├── systemd-journald.service
│ ├── systemd-logind.service
│ └── tmp.mount
└── user.slice
For comparison, here's the same container on recent Rawhide:
/sys/fs/cgroup/machine.slice/machine-lxc\x2d13550\x2damd64.scope/
└── libvirt
Anyway, those nested directories should not be a problem, because
virCgroupKillRecursiveInternal() removes them recursively, right?
Sort of. The function really does remove nested directories, but
it assumes that every directory has the same controller as the
rest. Just take a look at virCgroupV2KillRecursive() - it gets
'Any' controller (the first one it found in ".scope") and then
passes it to virCgroupKillRecursiveInternal().
This assumption is not true though. The controllers found in
".scope" are the following:
cpuset cpu io memory pids
while "libvirt" has fewer:
cpuset cpu io memory
Up until now it's not problem, because of how we order
controllers internally - "cpu" is the first and thus picking
"Any" controller returns just that. But the rest of directories
has no controllers, their "cgroup.controllers" is just empty.
What fixes the bug is dropping @controller argument from
virCgroupKillRecursiveInternal() and letting each iteration work
pick its own controller.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Historically, we declared pointer type to our types:
typedef struct _virXXX virXXX;
typedef virXXX *virXXXPtr;
But usefulness of such declaration is questionable, at best.
Unfortunately, we can't drop every such declaration - we have to
carry some over, because they are part of public API (e.g.
virDomainPtr). But for internal types - we can do drop them and
use what every other C project uses 'virXXX *'.
This change was generated by a very ugly shell script that
generated sed script which was then called over each file in the
repository. For the shell script refer to the cover letter:
https://listman.redhat.com/archives/libvir-list/2021-March/msg00537.html
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
When running on host with systemd we register VMs with machined.
In this case systemd creates the root VM cgroup for us. This has some
implications where one of them is that systemd owns all files inside
the root VM cgroup and we should not touch them.
We already use DBus calls for some of the APIs but for the remaining
ones we will continue accessing the files directly. Systemd doesn't
support threaded cgroups so we need to do this.
The reason why we don't use DBus for most of the APIs is that we already
have a code that works with files and we would have to check if systemd
supports each API.
This change introduces new topology on systemd hosts:
$ROOT
|
+- machine.slice
|
+- machine-qemu\x2d1\x2dvm1.scope
|
+- libvirt
|
+- emulator
+- vcpu0
+- vcpu0
compared to the previous topology:
$ROOT
|
+- machine.slice
|
+- machine-qemu\x2d1\x2dvm1.scope
|
+- emulator
+- vcpu0
+- vcpu0
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
When running on host with systemd we register VMs with machined.
In this case systemd creates the root VM cgroup for us. This has some
implications where one of them is that systemd owns all files inside
the root VM cgroup and we should not touch them.
If we change any value in file that systemd knows about it will be
changed to what systemd thinks it should be when executing
`systemctl daemon-reload`.
These are the APIs that we need to call using systemd because they set
limits that are proportional to sibling cgroups.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Using virtCgroupNewSelf() is not correct with cgroups v2 because the
the virt-host-validate process is executed from from the same cgroup
context as the terminal and usually not all controllers are enabled
by default.
To do a proper check we need to use the root cgroup to see what
controllers are actually available. Libvirt or systemd ensures that
all controllers are available for VMs as well.
This still doesn't solve the devices controller with cgroups v2 where
there is no controller as it was replaced by eBPF. Currently libvirt
tries to query eBPF programs which usually works only for root as
regular users will get permission denied for that operation.
Fixes: https://gitlab.com/libvirt/libvirt/-/issues/94
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Commit <99d2c6519ad18651b5959fa0a3366bcb2c1e44f3> removed parameter
from the function but did not modified ATTRIBUTE_NONNULL.
Reported-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
It is only used for debug and error purposes which can be easily
replaced by @placement.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Rewrite using GHashTable which already has interfaces for using a number
as hash key. Glib's implementation doesn't copy the key by default, so
we need to allocate it, but overal the interface is more suited for this
case.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
This function loads the BPF prog with prepared map into kernel and
attaches it into guest cgroup. It can be also used to replace existing
program in the cgroup if we need to resize BPF map to store more rules
for devices. The old program will be closed and removed from kernel.
There are two possible ways how to create BPF program:
- One way is to write simple C-like code which can by compiled into
BPF object file which can be loaded into kernel using elfutils.
- The second way is to define macros which look like assembler
instructions and can be used directly to create BPF program that
can be directly loaded into kernel.
Since the program is not too complex we can use the second option.
If there is no program, all devices are allowed, if there is some
program it is executed and based on the exit status the access is
denied for 0 and allowed for 1.
Our program will follow these rules:
- first it will try to look for the specific key using major and
minor to see if there is any rule for that specific device
- if there is no specific rule it will try to look for any rule that
matches only major of the device
- if there is no match with major it will try the same but with
minor of the device
- as the last attempt it will try to look for rule for all devices
and if there is no match it will return 0 to deny that access
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
If we need to get a path of specific file and we need to check its
existence before we use it then we can reuse that path to get value
for specific device. This way we will not build the path again in
virCgroupGetValueForBlkDev.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
If we need to get a path of specific file and we need to check its
existence before we use it then we can reuse that path to get/set
values instead of calling the existing get/set value functions which
would be building the path again.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Require that all headers are guarded by a symbol named
LIBVIRT_$FILENAME
where $FILENAME is the uppercased filename, with all characters
outside a-z changed into '_'.
Note we do not use a leading __ because that is technically a
namespace reserved for the toolchain.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This introduces a syntax-check script that validates header files use a
common layout:
/*
...copyright header...
*/
<one blank line>
#ifndef SYMBOL
# define SYMBOL
....content....
#endif /* SYMBOL */
For any file ending priv.h, before the #ifndef, we will require a
guard to prevent bogus imports:
#ifndef SYMBOL_ALLOW
# error ....
#endif /* SYMBOL_ALLOW */
<one blank line>
The many mistakes this script identifies are then fixed.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The rewrite to support cgroup v2 missed this function. In cgroup v2
we have different files to track tasks.
We would fail to remove cgroup on non-systemd OSes if there is any
extra process assigned to guest cgroup because we would not kill any
process form the guest cgroup.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
In many files there are header comments that contain an Author:
statement, supposedly reflecting who originally wrote the code.
In a large collaborative project like libvirt, any non-trivial
file will have been modified by a large number of different
contributors. IOW, the Author: comments are quickly out of date,
omitting people who have made significant contribitions.
In some places Author: lines have been added despite the person
merely being responsible for creating the file by moving existing
code out of another file. IOW, the Author: lines give an incorrect
record of authorship.
With this all in mind, the comments are useless as a means to identify
who to talk to about code in a particular file. Contributors will always
be better off using 'git log' and 'git blame' if they need to find the
author of a particular bit of code.
This commit thus deletes all Author: comments from the source and adds
a rule to prevent them reappearing.
The Copyright headers are similarly misleading and inaccurate, however,
we cannot delete these as they have legal meaning, despite being largely
inaccurate. In addition only the copyright holder is permitted to change
their respective copyright statement.
Reviewed-by: Erik Skultety <eskultet@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This enables to use both cgroup v1 and v2 at the same time together
with libvirt. It is supported by kernel and there is valid use-case,
not all controllers are implemented in cgroup v2 so there might be
configurations where administrator would enable these missing
controllers in cgroup v1.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Place cgroup v2 backend type before cgroup v1 to make it obvious
that cgroup v2 is preferred implementation.
Following patches will introduce support for hybrid configuration
which will allow us to use both at the same time, but we should
prefer cgroup v2 regardless.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
With the introduction of cgroup v2 there are new names used with
cgroups based on which version is used:
- legacy: cgroup v1
- unified: cgroup v2
- hybrid: cgroup v1 and cgroup v2
Let's use 'legacy' instead of 'cgroupv1' or 'controllers' in our code.
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
They all need virCgroupV1GetMemoryUnlimitedKB() so it's easier to
move them in one commit.
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
We need to update one test-case because now new cgroup object will be
created only if there is any cgroup backend available.
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
This will be required once cgroup v2 is introduced. The cgroup
detection is not simple and we will have multiple backends so we
should not just jump into the middle of the detection code.
In order to use virCgroupNewSelf we need to create all the remaining
data files:
- {name}.cgroups represents /proc/cgroups, it is a list of cgroup
controllers compiled into kernel
- {name}.self.cgroup represents /proc/self/cgroup, it describes
cgroups to which the process belongs
For "no-cgroups" we need to modify the expected behavior because
virCgroupNewSelf() will fail if there are no controllers available.
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Because we can set which files to return for cgroup tests there
is no need to have special function tailored to run tests.
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
This reverts commit 4da4a9fe0c.
Turns out, our code relies on virCgroupFree(&var) setting
var = NULL.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Using the new VIR_DEFINE_AUTOPTR_FUNC macro defined in
src/util/viralloc.h, define a new wrapper around an existing
cleanup function which will be called when a variable declared
with VIR_AUTOPTR macro goes out of scope. Also, drop the redundant
viralloc.h include, since that has moved from the source module into
the header.
When a variable of type virCgroupPtr is declared using
VIR_AUTOPTR, the function virCgroupFree will be run
automatically on it when it goes out of scope.
This commit also adds an intermediate typedef for virCgroup
type for use with the cleanup macros.
Signed-off-by: Sukrit Bhatnagar <skrtbhtngr@gmail.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>
If a cgroup controller is co-mounted with another, eg
/sys/fs/cgroup/cpu,cpuacct
Then it is a requirement that there exist symlinks at
/sys/fs/cgroup/cpu
/sys/fs/cgroup/cpuacct
pointing to the real mount point. Add support to virCgroupPtr
to detect and track these symlinks
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
The definition of structs for cgroups are kept in vircgroup.c since
they are intended to be private from users of the API. To enable
effective testing, however, they need to be accessible. To address
the latter issue, without compronmising the former, this introduces
a new vircgrouppriv.h file to hold the struct definitions.
To prevent other files including this private header, it requires
that __VIR_CGROUP_ALLOW_INCLUDE_PRIV_H__ be defined before inclusion
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
