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[RFC PATCH v3 3/6] qemu_interface: Added routine for loading the eBPF objects.

Andrew Melnychenko posted 6 patches 1 year, 9 months ago
There is a newer version of this series
[RFC PATCH v3 3/6] qemu_interface: Added routine for loading the eBPF objects.
Posted by Andrew Melnychenko 1 year, 9 months ago 
Also, added dependencies for libbpf with bpf option.

Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
---
 meson.build               |  7 ++++
 meson_options.txt         |  1 +
 src/qemu/meson.build      |  1 +
 src/qemu/qemu_interface.c | 83 +++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_interface.h |  4 ++
 5 files changed, 96 insertions(+)

diff --git a/meson.build b/meson.build
index e8b0094b91..e12a703a4d 100644
--- a/meson.build
+++ b/meson.build
@@ -998,6 +998,12 @@ else
   libkvm_dep = dependency('', required: false)
 endif
 
+libbpf_version = '1.1.0'
+libbpf_dep = dependency('libbpf', version: '>=' + libbpf_version, required: get_option('libbpf'))
+if libbpf_dep.found()
+    conf.set('WITH_BPF', 1)
+endif
+
 libiscsi_version = '1.18.0'
 libiscsi_dep = dependency('libiscsi', version: '>=' + libiscsi_version, required: get_option('libiscsi'))
 
@@ -2283,6 +2289,7 @@ libs_summary = {
   'dlopen': dlopen_dep.found(),
   'fuse': fuse_dep.found(),
   'glusterfs': glusterfs_dep.found(),
+  'libbpf': libbpf_dep.found(),
   'libiscsi': libiscsi_dep.found(),
   'libkvm': libkvm_dep.found(),
   'libnbd': libnbd_dep.found(),
diff --git a/meson_options.txt b/meson_options.txt
index 9d729b3e1f..9b7bd9d1f8 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -48,6 +48,7 @@ option('udev', type: 'feature', value: 'auto', description: 'udev support')
 option('wireshark_dissector', type: 'feature', value: 'auto', description: 'wireshark support')
 option('wireshark_plugindir', type: 'string', value: '', description: 'wireshark plugins directory for use when installing wireshark plugin')
 option('yajl', type: 'feature', value: 'auto', description: 'yajl support')
+option('libbpf', type: 'feature', value: 'auto', description: 'qemu libbpf support')
 
 
 # build driver options
diff --git a/src/qemu/meson.build b/src/qemu/meson.build
index 907893d431..de7ae87d5b 100644
--- a/src/qemu/meson.build
+++ b/src/qemu/meson.build
@@ -105,6 +105,7 @@ if conf.has('WITH_QEMU')
       selinux_dep,
       src_dep,
       xdr_dep,
+      libbpf_dep,
     ],
     include_directories: [
       conf_inc_dir,
diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c
index c2007c7043..ec8cf18d86 100644
--- a/src/qemu/qemu_interface.c
+++ b/src/qemu/qemu_interface.c
@@ -38,6 +38,10 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
+#ifdef WITH_BPF
+#include <bpf/libbpf.h>
+#endif
+
 #define VIR_FROM_THIS VIR_FROM_QEMU
 
 VIR_LOG_INIT("qemu.qemu_interface");
@@ -432,3 +436,82 @@ qemuInterfaceOpenVhostNet(virDomainObj *vm,
     virDomainAuditNetDevice(vm->def, net, vhostnet_path, vhostfdSize);
     return 0;
 }
+
+#ifdef WITH_BPF
+
+int
+qemuInterfaceLoadEbpf(const char *ebpfObject, void **retLibbpfObj, int *fds, size_t nfds)
+{
+    int err = 0;
+    size_t i = 0;
+    struct bpf_program *prog;
+    struct bpf_map *map;
+    struct bpf_object *obj;
+    size_t ebpfSize = 0;
+    g_autofree void *ebpfRawData = NULL;
+
+    ebpfRawData = g_base64_decode(ebpfObject, &ebpfSize);
+    if (ebpfRawData == NULL) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't decode the eBPF from base64"));
+        return -1;
+    }
+
+    obj = bpf_object__open_mem(ebpfRawData, ebpfSize, NULL);
+    err = libbpf_get_error(obj);
+    if (err) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't open eBPF object"));
+        return -1;
+    }
+
+
+    err = bpf_object__load(obj);
+    if (err) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't load eBPF object"));
+        return -1;
+    }
+
+    bpf_object__for_each_program(prog, obj) {
+        fds[i] = bpf_program__fd(prog);
+        ++i;
+        if (i > nfds) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("to much file descriptors in eBPF"));
+            return -1;
+        }
+    }
+
+    bpf_object__for_each_map(map, obj) {
+        fds[i] = bpf_map__fd(map);
+        ++i;
+        if (i > nfds) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("to much file descriptors in eBPF"));
+            return -1;
+        }
+    }
+
+    *retLibbpfObj = obj;
+
+    return i - 1;
+}
+
+
+void
+qemuInterfaceCloseEbpf(void *libbpfObj)
+{
+    if (libbpfObj)
+        bpf_object__close(libbpfObj);
+}
+#else
+
+int
+qemuInterfaceLoadEbpf(const char *ebpfObject G_GNUC_UNUSED, void **retLibbpfObj G_GNUC_UNUSED,
+                      int *fds G_GNUC_UNUSED, size_t nfds G_GNUC_UNUSED)
+{
+    return -1;
+}
+
+void
+qemuInterfaceCloseEbpf(void *libbpfObj G_GNUC_UNUSED)
+{
+}
+
+#endif
diff --git a/src/qemu/qemu_interface.h b/src/qemu/qemu_interface.h
index aee5f9efb0..b6f39550cd 100644
--- a/src/qemu/qemu_interface.h
+++ b/src/qemu/qemu_interface.h
@@ -44,3 +44,7 @@ int qemuInterfaceOpenVhostNet(virDomainObj *def,
 
 int qemuInterfacePrepareSlirp(virQEMUDriver *driver,
                               virDomainNetDef *net);
+
+int qemuInterfaceLoadEbpf(const char *ebpfObject, void **retLibbpfObj, int *fds, size_t nfds);
+
+void qemuInterfaceCloseEbpf(void *libbpfObj);
-- 
2.44.0
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Re: [RFC PATCH v3 3/6] qemu_interface: Added routine for loading the eBPF objects.
Posted by Michal Prívozník 1 year, 8 months ago 
On 5/12/24 21:45, Andrew Melnychenko wrote:
> Also, added dependencies for libbpf with bpf option.
> 
> Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
> ---
>  meson.build               |  7 ++++
>  meson_options.txt         |  1 +
>  src/qemu/meson.build      |  1 +
>  src/qemu/qemu_interface.c | 83 +++++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_interface.h |  4 ++
>  5 files changed, 96 insertions(+)


libvirt.spec.in should be changed too to either selectively disable this
feature or enable it and drag in the requirement (preferred).

> 
> diff --git a/meson.build b/meson.build
> index e8b0094b91..e12a703a4d 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -998,6 +998,12 @@ else
>    libkvm_dep = dependency('', required: false)
>  endif
>  
> +libbpf_version = '1.1.0'
> +libbpf_dep = dependency('libbpf', version: '>=' + libbpf_version, required: get_option('libbpf'))
> +if libbpf_dep.found()
> +    conf.set('WITH_BPF', 1)
> +endif
> +
>  libiscsi_version = '1.18.0'
>  libiscsi_dep = dependency('libiscsi', version: '>=' + libiscsi_version, required: get_option('libiscsi'))
>  
> @@ -2283,6 +2289,7 @@ libs_summary = {
>    'dlopen': dlopen_dep.found(),
>    'fuse': fuse_dep.found(),
>    'glusterfs': glusterfs_dep.found(),
> +  'libbpf': libbpf_dep.found(),
>    'libiscsi': libiscsi_dep.found(),
>    'libkvm': libkvm_dep.found(),
>    'libnbd': libnbd_dep.found(),
> diff --git a/meson_options.txt b/meson_options.txt
> index 9d729b3e1f..9b7bd9d1f8 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -48,6 +48,7 @@ option('udev', type: 'feature', value: 'auto', description: 'udev support')
>  option('wireshark_dissector', type: 'feature', value: 'auto', description: 'wireshark support')
>  option('wireshark_plugindir', type: 'string', value: '', description: 'wireshark plugins directory for use when installing wireshark plugin')
>  option('yajl', type: 'feature', value: 'auto', description: 'yajl support')
> +option('libbpf', type: 'feature', value: 'auto', description: 'qemu libbpf support')
>  
>  
>  # build driver options
> diff --git a/src/qemu/meson.build b/src/qemu/meson.build
> index 907893d431..de7ae87d5b 100644
> --- a/src/qemu/meson.build
> +++ b/src/qemu/meson.build
> @@ -105,6 +105,7 @@ if conf.has('WITH_QEMU')
>        selinux_dep,
>        src_dep,
>        xdr_dep,
> +      libbpf_dep,

We tend to keep this kind of lists sorted alphabetically.

>      ],
>      include_directories: [
>        conf_inc_dir,
> diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c
> index c2007c7043..ec8cf18d86 100644
> --- a/src/qemu/qemu_interface.c
> +++ b/src/qemu/qemu_interface.c
> @@ -38,6 +38,10 @@
>  #include <sys/stat.h>
>  #include <fcntl.h>
>  
> +#ifdef WITH_BPF
> +#include <bpf/libbpf.h>

s/#include/# include/
if you'd install 'cppi' then a syntax-check rule of ours would have
warned you about this.

> +#endif
> +
>  #define VIR_FROM_THIS VIR_FROM_QEMU
>  
>  VIR_LOG_INIT("qemu.qemu_interface");
> @@ -432,3 +436,82 @@ qemuInterfaceOpenVhostNet(virDomainObj *vm,
>      virDomainAuditNetDevice(vm->def, net, vhostnet_path, vhostfdSize);
>      return 0;
>  }
> +
> +#ifdef WITH_BPF
> +
> +int
> +qemuInterfaceLoadEbpf(const char *ebpfObject, void **retLibbpfObj, int *fds, size_t nfds)
> +{
> +    int err = 0;
> +    size_t i = 0;
> +    struct bpf_program *prog;
> +    struct bpf_map *map;
> +    struct bpf_object *obj;
> +    size_t ebpfSize = 0;
> +    g_autofree void *ebpfRawData = NULL;
> +
> +    ebpfRawData = g_base64_decode(ebpfObject, &ebpfSize);
> +    if (ebpfRawData == NULL) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't decode the eBPF from base64"));
> +        return -1;
> +    }
> +
> +    obj = bpf_object__open_mem(ebpfRawData, ebpfSize, NULL);
> +    err = libbpf_get_error(obj);
> +    if (err) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't open eBPF object"));
> +        return -1;
> +    }

IIUC, libbpf_get_error() is deprecated and upon failure bpf_object_*()
APIs return NULL and set errno. Thus this (and the rest) could look
something like this:

  obj = bpf_object__open_mem(...);
  if (!obj) {
      virReportSystemError(errno, "%s", _("can't open eBPF object"));
      return -1;
  }

> +
> +
> +    err = bpf_object__load(obj);
> +    if (err) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't load eBPF object"));
> +        return -1;
> +    }
> +
> +    bpf_object__for_each_program(prog, obj) {
> +        fds[i] = bpf_program__fd(prog);
> +        ++i;
> +        if (i > nfds) {
> +            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("to much file descriptors in eBPF"));
> +            return -1;
> +        }
> +    }
> +
> +    bpf_object__for_each_map(map, obj) {
> +        fds[i] = bpf_map__fd(map);
> +        ++i;
> +        if (i > nfds) {
> +            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("to much file descriptors in eBPF"));
> +            return -1;
> +        }
> +    }
> +
> +    *retLibbpfObj = obj;
> +
> +    return i - 1;
> +}
> +
> +
> +void
> +qemuInterfaceCloseEbpf(void *libbpfObj)
> +{
> +    if (libbpfObj)
> +        bpf_object__close(libbpfObj);
> +}
> +#else
> +
> +int
> +qemuInterfaceLoadEbpf(const char *ebpfObject G_GNUC_UNUSED, void **retLibbpfObj G_GNUC_UNUSED,
> +                      int *fds G_GNUC_UNUSED, size_t nfds G_GNUC_UNUSED)
> +{
> +    return -1;

Maybe this can return -2 so that callers can distinguish this version
and the version above failing?

> +}

Michal
Re: [RFC PATCH v3 3/6] qemu_interface: Added routine for loading the eBPF objects.
Posted by Andrew Melnichenko 1 year, 8 months ago 
Hi all,

On Fri, May 17, 2024 at 5:00 PM Michal Prívozník <mprivozn@redhat.com> wrote:
>
> On 5/12/24 21:45, Andrew Melnychenko wrote:
> > Also, added dependencies for libbpf with bpf option.
> >
> > Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
> > ---
> >  meson.build               |  7 ++++
> >  meson_options.txt         |  1 +
> >  src/qemu/meson.build      |  1 +
> >  src/qemu/qemu_interface.c | 83 +++++++++++++++++++++++++++++++++++++++
> >  src/qemu/qemu_interface.h |  4 ++
> >  5 files changed, 96 insertions(+)
>
>
> libvirt.spec.in should be changed too to either selectively disable this
> feature or enable it and drag in the requirement (preferred).

Yes, I'll "enable it" in the next version.

>
> >
> > diff --git a/meson.build b/meson.build
> > index e8b0094b91..e12a703a4d 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -998,6 +998,12 @@ else
> >    libkvm_dep = dependency('', required: false)
> >  endif
> >
> > +libbpf_version = '1.1.0'
> > +libbpf_dep = dependency('libbpf', version: '>=' + libbpf_version, required: get_option('libbpf'))
> > +if libbpf_dep.found()
> > +    conf.set('WITH_BPF', 1)
> > +endif
> > +
> >  libiscsi_version = '1.18.0'
> >  libiscsi_dep = dependency('libiscsi', version: '>=' + libiscsi_version, required: get_option('libiscsi'))
> >
> > @@ -2283,6 +2289,7 @@ libs_summary = {
> >    'dlopen': dlopen_dep.found(),
> >    'fuse': fuse_dep.found(),
> >    'glusterfs': glusterfs_dep.found(),
> > +  'libbpf': libbpf_dep.found(),
> >    'libiscsi': libiscsi_dep.found(),
> >    'libkvm': libkvm_dep.found(),
> >    'libnbd': libnbd_dep.found(),
> > diff --git a/meson_options.txt b/meson_options.txt
> > index 9d729b3e1f..9b7bd9d1f8 100644
> > --- a/meson_options.txt
> > +++ b/meson_options.txt
> > @@ -48,6 +48,7 @@ option('udev', type: 'feature', value: 'auto', description: 'udev support')
> >  option('wireshark_dissector', type: 'feature', value: 'auto', description: 'wireshark support')
> >  option('wireshark_plugindir', type: 'string', value: '', description: 'wireshark plugins directory for use when installing wireshark plugin')
> >  option('yajl', type: 'feature', value: 'auto', description: 'yajl support')
> > +option('libbpf', type: 'feature', value: 'auto', description: 'qemu libbpf support')
> >
> >
> >  # build driver options
> > diff --git a/src/qemu/meson.build b/src/qemu/meson.build
> > index 907893d431..de7ae87d5b 100644
> > --- a/src/qemu/meson.build
> > +++ b/src/qemu/meson.build
> > @@ -105,6 +105,7 @@ if conf.has('WITH_QEMU')
> >        selinux_dep,
> >        src_dep,
> >        xdr_dep,
> > +      libbpf_dep,
>
> We tend to keep this kind of lists sorted alphabetically.
>
> >      ],
> >      include_directories: [
> >        conf_inc_dir,
> > diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c
> > index c2007c7043..ec8cf18d86 100644
> > --- a/src/qemu/qemu_interface.c
> > +++ b/src/qemu/qemu_interface.c
> > @@ -38,6 +38,10 @@
> >  #include <sys/stat.h>
> >  #include <fcntl.h>
> >
> > +#ifdef WITH_BPF
> > +#include <bpf/libbpf.h>
>
> s/#include/# include/
> if you'd install 'cppi' then a syntax-check rule of ours would have
> warned you about this.
>
> > +#endif
> > +
> >  #define VIR_FROM_THIS VIR_FROM_QEMU
> >
> >  VIR_LOG_INIT("qemu.qemu_interface");
> > @@ -432,3 +436,82 @@ qemuInterfaceOpenVhostNet(virDomainObj *vm,
> >      virDomainAuditNetDevice(vm->def, net, vhostnet_path, vhostfdSize);
> >      return 0;
> >  }
> > +
> > +#ifdef WITH_BPF
> > +
> > +int
> > +qemuInterfaceLoadEbpf(const char *ebpfObject, void **retLibbpfObj, int *fds, size_t nfds)
> > +{
> > +    int err = 0;
> > +    size_t i = 0;
> > +    struct bpf_program *prog;
> > +    struct bpf_map *map;
> > +    struct bpf_object *obj;
> > +    size_t ebpfSize = 0;
> > +    g_autofree void *ebpfRawData = NULL;
> > +
> > +    ebpfRawData = g_base64_decode(ebpfObject, &ebpfSize);
> > +    if (ebpfRawData == NULL) {
> > +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't decode the eBPF from base64"));
> > +        return -1;
> > +    }
> > +
> > +    obj = bpf_object__open_mem(ebpfRawData, ebpfSize, NULL);
> > +    err = libbpf_get_error(obj);
> > +    if (err) {
> > +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't open eBPF object"));
> > +        return -1;
> > +    }
>
> IIUC, libbpf_get_error() is deprecated and upon failure bpf_object_*()
> APIs return NULL and set errno. Thus this (and the rest) could look
> something like this:
>
>   obj = bpf_object__open_mem(...);
>   if (!obj) {
>       virReportSystemError(errno, "%s", _("can't open eBPF object"));
>       return -1;
>   }
>

Ok. originally I've tied to omit errno and use VIR_ERR* macros.

> > +
> > +
> > +    err = bpf_object__load(obj);
> > +    if (err) {
> > +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("can't load eBPF object"));
> > +        return -1;
> > +    }
> > +
> > +    bpf_object__for_each_program(prog, obj) {
> > +        fds[i] = bpf_program__fd(prog);
> > +        ++i;
> > +        if (i > nfds) {
> > +            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("to much file descriptors in eBPF"));
> > +            return -1;
> > +        }
> > +    }
> > +
> > +    bpf_object__for_each_map(map, obj) {
> > +        fds[i] = bpf_map__fd(map);
> > +        ++i;
> > +        if (i > nfds) {
> > +            virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("to much file descriptors in eBPF"));
> > +            return -1;
> > +        }
> > +    }
> > +
> > +    *retLibbpfObj = obj;
> > +
> > +    return i - 1;
> > +}
> > +
> > +
> > +void
> > +qemuInterfaceCloseEbpf(void *libbpfObj)
> > +{
> > +    if (libbpfObj)
> > +        bpf_object__close(libbpfObj);
> > +}
> > +#else
> > +
> > +int
> > +qemuInterfaceLoadEbpf(const char *ebpfObject G_GNUC_UNUSED, void **retLibbpfObj G_GNUC_UNUSED,
> > +                      int *fds G_GNUC_UNUSED, size_t nfds G_GNUC_UNUSED)
> > +{
> > +    return -1;
>
> Maybe this can return -2 so that callers can distinguish this version
> and the version above failing?
>

Ok.

> > +}
>
> Michal
>

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