hw/arm/virt: dt: add rng-seed property

In 60592cfed2 ("hw/arm/virt: dt: add kaslr-seed property"), the
kaslr-seed property was added, but the equally as important rng-seed
property was forgotten about, which has identical semantics for a
similar purpose. This commit implements it in exactly the same way as
kaslr-seed. It then changes the name of the disabling option to reflect
that this has more to do with randomness vs determinism, rather than
something particular about kaslr.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
[PMM: added deprecated.rst section for the deprecation]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 27 insertions, 17 deletions

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 5502aa60c8..9633f822f3 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -221,14 +221,18 @@ static bool cpu_type_valid(const char *cpu)
     return false;
 }
 
-static void create_kaslr_seed(MachineState *ms, const char *node)
+static void create_randomness(MachineState *ms, const char *node)
 {
-    uint64_t seed;
+    struct {
+        uint64_t kaslr;
+        uint8_t rng[32];
+    } seed;
 
     if (qemu_guest_getrandom(&seed, sizeof(seed), NULL)) {
         return;
     }
-    qemu_fdt_setprop_u64(ms->fdt, node, "kaslr-seed", seed);
+    qemu_fdt_setprop_u64(ms->fdt, node, "kaslr-seed", seed.kaslr);
+    qemu_fdt_setprop(ms->fdt, node, "rng-seed", seed.rng, sizeof(seed.rng));
 }
 
 static void create_fdt(VirtMachineState *vms)
@@ -251,14 +255,14 @@ static void create_fdt(VirtMachineState *vms)
 
     /* /chosen must exist for load_dtb to fill in necessary properties later */
     qemu_fdt_add_subnode(fdt, "/chosen");
-    if (vms->dtb_kaslr_seed) {
-        create_kaslr_seed(ms, "/chosen");
+    if (vms->dtb_randomness) {
+        create_randomness(ms, "/chosen");
     }
 
     if (vms->secure) {
         qemu_fdt_add_subnode(fdt, "/secure-chosen");
-        if (vms->dtb_kaslr_seed) {
-            create_kaslr_seed(ms, "/secure-chosen");
+        if (vms->dtb_randomness) {
+            create_randomness(ms, "/secure-chosen");
         }
     }
 
@@ -2340,18 +2344,18 @@ static void virt_set_its(Object *obj, bool value, Error **errp)
     vms->its = value;
 }
 
-static bool virt_get_dtb_kaslr_seed(Object *obj, Error **errp)
+static bool virt_get_dtb_randomness(Object *obj, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
 
-    return vms->dtb_kaslr_seed;
+    return vms->dtb_randomness;
 }
 
-static void virt_set_dtb_kaslr_seed(Object *obj, bool value, Error **errp)
+static void virt_set_dtb_randomness(Object *obj, bool value, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
 
-    vms->dtb_kaslr_seed = value;
+    vms->dtb_randomness = value;
 }
 
 static char *virt_get_oem_id(Object *obj, Error **errp)
@@ -2980,12 +2984,18 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
                                           "Set on/off to enable/disable "
                                           "ITS instantiation");
 
+    object_class_property_add_bool(oc, "dtb-randomness",
+                                   virt_get_dtb_randomness,
+                                   virt_set_dtb_randomness);
+    object_class_property_set_description(oc, "dtb-randomness",
+                                          "Set off to disable passing random or "
+                                          "non-deterministic dtb nodes to guest");
+
     object_class_property_add_bool(oc, "dtb-kaslr-seed",
-                                   virt_get_dtb_kaslr_seed,
-                                   virt_set_dtb_kaslr_seed);
+                                   virt_get_dtb_randomness,
+                                   virt_set_dtb_randomness);
     object_class_property_set_description(oc, "dtb-kaslr-seed",
-                                          "Set off to disable passing of kaslr-seed "
-                                          "dtb node to guest");
+                                          "Deprecated synonym of dtb-randomness");
 
     object_class_property_add_str(oc, "x-oem-id",
                                   virt_get_oem_id,
@@ -3053,8 +3063,8 @@ static void virt_instance_init(Object *obj)
     /* MTE is disabled by default.  */
     vms->mte = false;
 
-    /* Supply a kaslr-seed by default */
-    vms->dtb_kaslr_seed = true;
+    /* Supply kaslr-seed and rng-seed by default */
+    vms->dtb_randomness = true;
 
     vms->irqmap = a15irqmap;