m68k: virt: pass RNG seed via bootinfo block

This commit wires up bootinfo's RNG seed attribute so that Linux VMs can
have their RNG seeded from the earliest possible time in boot, just like
the "rng-seed" device tree property on those platforms. The link
contains the corresponding Linux patch.

Link: https://lore.kernel.org/lkml/20220626111509.330159-1-Jason@zx2c4.com/
Based-on: <20220625152318.120849-1-Jason@zx2c4.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Message-Id: <20220626111804.330745-1-Jason@zx2c4.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

diff --git a/hw/m68k/bootinfo.h b/hw/m68k/bootinfo.h
index ff4e155a3cc84b8057a6bf20c16848f098c3de2b..bd8b212fd35ce216917e07eb67783b5b69f1e11b 100644 (file)
--- a/hw/m68k/bootinfo.h
+++ b/hw/m68k/bootinfo.h
@@ -56,4 +56,20 @@
         stb_phys(as, base++, 0); \
         base = (base + 1) & ~1; \
     } while (0)
+
+#define BOOTINFODATA(as, base, id, data, len) \
+    do { \
+        int i; \
+        stw_phys(as, base, id); \
+        base += 2; \
+        stw_phys(as, base, \
+                 (sizeof(struct bi_record) + len + 3) & ~1); \
+        base += 2; \
+        stw_phys(as, base, len); \
+        base += 2; \
+        for (i = 0; i < len; ++i) { \
+            stb_phys(as, base++, data[i]); \
+        } \
+        base = (base + 1) & ~1; \
+    } while (0)
 #endif

diff --git a/hw/m68k/virt.c b/hw/m68k/virt.c
index e215aa3d42170872b86b1bbf15e65a65d4d88837..0aa383fa6bdae194fbc5cb8208d5364e37a2a1ef 100644 (file)
--- a/hw/m68k/virt.c
+++ b/hw/m68k/virt.c
@@ -9,6 +9,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/units.h"
+#include "qemu/guest-random.h"
 #include "sysemu/sysemu.h"
 #include "cpu.h"
 #include "hw/boards.h"
@@ -120,6 +121,7 @@ static void virt_init(MachineState *machine)
     hwaddr io_base;
     int i;
     ResetInfo *reset_info;
+    uint8_t rng_seed[32];
 
     if (ram_size > 3399672 * KiB) {
         /*
@@ -245,6 +247,11 @@ static void virt_init(MachineState *machine)
                         kernel_cmdline);
         }
 
+       /* Pass seed to RNG. */
+       qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+       BOOTINFODATA(cs->as, parameters_base, BI_VIRT_RNG_SEED,
+                    rng_seed, sizeof(rng_seed));
+
         /* load initrd */
         if (initrd_filename) {
             initrd_size = get_image_size(initrd_filename);

diff --git a/include/standard-headers/asm-m68k/bootinfo-virt.h b/include/standard-headers/asm-m68k/bootinfo-virt.h
index 81be1e092497b241f6f31ae0ea67e0baa57f5d40..1b1ffd4705d683fdeb1425041364f33b7002f735 100644 (file)
--- a/include/standard-headers/asm-m68k/bootinfo-virt.h
+++ b/include/standard-headers/asm-m68k/bootinfo-virt.h
@@ -12,6 +12,7 @@
 #define BI_VIRT_GF_TTY_BASE    0x8003
 #define BI_VIRT_VIRTIO_BASE    0x8004
 #define BI_VIRT_CTRL_BASE      0x8005
+#define BI_VIRT_RNG_SEED       0x8006
 
 #define VIRT_BOOTI_VERSION     MK_BI_VERSION(2, 0)