qemu: Add VirtIORNG random data source

Adds /dev/urandom from the host as a source for random data so the guest
does not block on calls to getentropy() etc.

Signed-off-by: Albert Schwarzkopf <githubc@quitesimple.org>
Reviewed-by: Joakim Bech <joakim.bech@linaro.org>

common.mk

@@ -320,6 +320,9 @@ edk2-clean-common:
 # QEMU / QEMUv8
 ################################################################################
 QEMU_CONFIGURE_PARAMS_COMMON = --cc="$(CCACHE)gcc" --extra-cflags="-Wno-error"
+QEMU_EXTRA_ARGS +=\
+	-object rng-random,filename=/dev/urandom,id=rng0 \
+	-device virtio-rng-pci,rng=rng0,max-bytes=1024,period=1000
 
 ifeq ($(QEMU_VIRTFS_ENABLE),y)
 QEMU_CONFIGURE_PARAMS_COMMON +=  --enable-virtfs