Add a new RNG backend using QEMU builtin getrandom function.
It can be created and used with something like:
... -object rng-builtin,id=rng0 -device virtio-rng,rng=rng0 ...
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Laurent Vivier <address@hidden>
---
Notes:
This patch applies on top of
"[PATCH v5 00/24] Add qemu_getrandom and ARMv8.5-RNG etc"
Based-on: address@hidden
v2: Update qemu-options.hx
describe the new backend and specify virtio-rng uses the
rng-random by default (do we want to change this?)
backends/Makefile.objs | 2 +-
backends/rng-builtin.c | 56 ++++++++++++++++++++++++++++++++++++++++++
qemu-options.hx | 10 +++++++-
3 files changed, 66 insertions(+), 2 deletions(-)
create mode 100644 backends/rng-builtin.c
diff --git a/backends/Makefile.objs b/backends/Makefile.objs
index ff619d31b461..8da4a508d97b 100644
--- a/backends/Makefile.objs
+++ b/backends/Makefile.objs
@@ -1,4 +1,4 @@
-common-obj-y += rng.o rng-egd.o
+common-obj-y += rng.o rng-egd.o rng-builtin.o
common-obj-$(CONFIG_POSIX) += rng-random.o
common-obj-$(CONFIG_TPM) += tpm.o
diff --git a/backends/rng-builtin.c b/backends/rng-builtin.c
new file mode 100644
index 000000000000..b1264b745407
--- /dev/null
+++ b/backends/rng-builtin.c
@@ -0,0 +1,56 @@
+/*
+ * QEMU Builtin Random Number Generator Backend
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "sysemu/rng.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/main-loop.h"
+#include "qemu/guest-random.h"
+
+#define TYPE_RNG_BUILTIN "rng-builtin"
+#define RNG_BUILTIN(obj) OBJECT_CHECK(RngBuiltin, (obj), TYPE_RNG_BUILTIN)
+
+typedef struct RngBuiltin {
+ RngBackend parent;
+} RngBuiltin;
+
+static void rng_builtin_request_entropy(RngBackend *b, RngRequest *req)
+{
+ RngBuiltin *s = RNG_BUILTIN(b);
+
+ while (!QSIMPLEQ_EMPTY(&s->parent.requests)) {
+ RngRequest *req = QSIMPLEQ_FIRST(&s->parent.requests);
+
+ qemu_guest_getrandom_nofail(req->data, req->size);
+
+ req->receive_entropy(req->opaque, req->data, req->size);
+
+ rng_backend_finalize_request(&s->parent, req);
+ }
+}
+
+static void rng_builtin_class_init(ObjectClass *klass, void *data)
+{
+ RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
+
+ rbc->request_entropy = rng_builtin_request_entropy;
+}
+
+static const TypeInfo rng_builtin_info = {
+ .name = TYPE_RNG_BUILTIN,
+ .parent = TYPE_RNG_BACKEND,
+ .instance_size = sizeof(RngBuiltin),
+ .class_init = rng_builtin_class_init,
+};
+
+static void register_types(void)
+{
+ type_register_static(&rng_builtin_info);
+}
+
+type_init(register_types);
diff --git a/qemu-options.hx b/qemu-options.hx
index 0191ef8b1eb7..3e2a51c691b0 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4280,13 +4280,21 @@ other options.
The @option{share} boolean option is @var{on} by default with memfd.
address@hidden -object rng-builtin,address@hidden
+
+Creates a random number generator backend which obtains entropy from
+QEMU builtin functions. The @option{id} parameter is a unique ID that
+will be used to reference this entropy backend from the @option{virtio-rng}
+device.
+
@item -object rng-random,address@hidden,address@hidden/dev/random}
Creates a random number generator backend which obtains entropy from
a device on the host. The @option{id} parameter is a unique ID that
will be used to reference this entropy backend from the @option{virtio-rng}
device.