From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Sun, 26 Jun 2022 11:18:04 +0000 (+0200)
Subject: m68k: virt: pass RNG seed via bootinfo block
X-Git-Tag: v7.1.0-rc0~35^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a988465d0eb7e2ee31a3679bbe3fbe71681820da;p=thirdparty%2Fqemu.git

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 ff4e155a3cc..bd8b212fd35 100644
--- 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 e215aa3d421..0aa383fa6bd 100644
--- 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 81be1e09249..1b1ffd4705d 100644
--- 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)