hw/loongarch: virt: pass random seed to fdt

If the FDT contains /chosen/rng-seed, then the Linux RNG will use it to
initialize early. Set this using the usual guest random number
generation function.

This is the same procedure that's done in b91b6b5a2c ("hw/microblaze:
pass random seed to fdt"), e4b4f0b71c ("hw/riscv: virt: pass random seed
to fdt"), c6fe3e6b4c ("hw/openrisc: virt: pass random seed to fdt"),
67f7e426e5 ("hw/i386: pass RNG seed via setup_data entry"), c287941a4d
("hw/rx: pass random seed to fdt"), 5e19cc68fb ("hw/mips: boston: pass
random seed to fdt"), 6b23a67916 ("hw/nios2: virt: pass random seed to fdt")
c4b075318e ("hw/ppc: pass random seed to fdt"), and 5242876f37
("hw/arm/virt: dt: add rng-seed property").

These earlier commits later were amended to rerandomize the RNG seed on
snapshot load, but the LoongArch code somehow already does that, despite
not having this patch here, presumably due to some lucky copy and
pasting.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20240905153316.2038769-1-Jason@zx2c4.com>
Signed-off-by: Song Gao <gaosong@loongson.cn>

diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 76dd29a39166a7ea0f359c01d958a3728b82fb1c..81b1f9486fa55464087b37ef9a71c5cccd34c43e 100644 (file)
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -48,6 +48,7 @@
 #include "hw/block/flash.h"
 #include "hw/virtio/virtio-iommu.h"
 #include "qemu/error-report.h"
+#include "qemu/guest-random.h"
 
 static bool virt_is_veiointc_enabled(LoongArchVirtMachineState *lvms)
 {
@@ -303,6 +304,7 @@ static void fdt_add_uart_node(LoongArchVirtMachineState *lvms,
 static void create_fdt(LoongArchVirtMachineState *lvms)
 {
     MachineState *ms = MACHINE(lvms);
+    uint8_t rng_seed[32];
 
     ms->fdt = create_device_tree(&lvms->fdt_size);
     if (!ms->fdt) {
@@ -316,6 +318,10 @@ static void create_fdt(LoongArchVirtMachineState *lvms)
     qemu_fdt_setprop_cell(ms->fdt, "/", "#address-cells", 0x2);
     qemu_fdt_setprop_cell(ms->fdt, "/", "#size-cells", 0x2);
     qemu_fdt_add_subnode(ms->fdt, "/chosen");
+
+    /* Pass seed to RNG */
+    qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+    qemu_fdt_setprop(ms->fdt, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
 }
 
 static void fdt_add_cpu_nodes(const LoongArchVirtMachineState *lvms)