Re: [libvirt] [PATCH v3 02/15] vircgroup: introduce virCgroupV2DevicesAvailable

There is no exact way how to figure out whether BPF devices support is compiled into kernel. One way is to check kernel configure options but this is not reliable as it may not be available. Let's try to do syscall to which will list BPF cgroup device programs. Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; --- configure.ac | 3 +- src/Makefile.am | 2 + src/libvirt_private.syms | 3 ++ src/util/Makefile.inc.am | 2 + src/util/vircgroupv2.c | 7 +++- src/util/vircgroupv2devices.c | 73 +++++++++++++++++++++++++++++++++++ src/util/vircgroupv2devices.h | 27 +++++++++++++ 7 files changed, 115 insertions(+), 2 deletions(-) create mode 100644 src/util/vircgroupv2devices.c create mode 100644 src/util/vircgroupv2devices.h new file mode 100644 index 0000000000..10080d4fff --- /dev/null +++ b/src/util/vircgroupv2devices.c @@ -0,0 +1,73 @@ +/* + * vircgroupv2devices.c: methods for cgroups v2 BPF devices + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <http://www.gnu.org/licenses/>;. + */ +#include <config.h> + +#if HAVE_DECL_BPF_CGROUP_DEVICE +# include <fcntl.h> +# include <linux/bpf.h> +# include <sys/stat.h> +# include <sys/syscall.h> +# include <sys/types.h> +#endif /* !HAVE_DECL_BPF_CGROUP_DEVICE */ + +#include "internal.h" + +#define LIBVIRT_VIRCGROUPPRIV_H_ALLOW +#include "vircgrouppriv.h" + +#include "virbpf.h" +#include "vircgroup.h" +#include "vircgroupv2devices.h" +#include "virfile.h" +#include "virlog.h" + +VIR_LOG_INIT("util.cgroup"); + +#define VIR_FROM_THIS VIR_FROM_CGROUP + +#if HAVE_DECL_BPF_CGROUP_DEVICE +bool +virCgroupV2DevicesAvailable(virCgroupPtr group) +{ + bool ret = false; + int cgroupfd = -1;

+ unsigned int progCnt = 0; + + cgroupfd = open(group->unified.mountPoint, O_RDONLY); + if (cgroupfd < 0) { + VIR_DEBUG("failed to open cgroup '%s'", group->unified.mountPoint); + goto cleanup; + } + + if (virBPFQueryProg(cgroupfd, 0, BPF_CGROUP_DEVICE, &progCnt, NULL) < 0) { + VIR_DEBUG("failed to query cgroup progs"); + goto cleanup; + } + + ret = true; + cleanup: + VIR_FORCE_CLOSE(cgroupfd); + return ret; +} +#else /* !HAVE_DECL_BPF_CGROUP_DEVICE */ +bool +virCgroupV2DevicesAvailable(virCgroupPtr group ATTRIBUTE_UNUSED) +{ + return false; +} +#endif /* !HAVE_DECL_BPF_CGROUP_DEVICE */ diff --git a/src/util/vircgroupv2devices.h b/src/util/vircgroupv2devices.h new file mode 100644 index 0000000000..2ab35681db --- /dev/null +++ b/src/util/vircgroupv2devices.h @@ -0,0 +1,27 @@ +/* + * vircgroupv2devices.h: methods for cgroups v2 BPF devices + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <http://www.gnu.org/licenses/>;. + */ +