[PATCH] m68k: virt: pass RNG seed via bootinfo block

["Jason A. Donenfeld" <Jason@zx2c4.com>]

Other virt VMs can pass RNG seeds via the "rng-seed" device tree
property or via UEFI, but m68k doesn't have either. Instead it has its
own bootinfo protocol. So this commit adds support for receiving a RNG
seed from it, which will be used at the earliest possible time in boot,
just like device tree.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/m68k/include/uapi/asm/bootinfo-virt.h | 1 +
 arch/m68k/virt/config.c                    | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/m68k/include/uapi/asm/bootinfo-virt.h b/arch/m68k/include/uapi/asm/bootinfo-virt.h
index e4db7e2213ab..7c3044acdf4a 100644
--- a/arch/m68k/include/uapi/asm/bootinfo-virt.h
+++ b/arch/m68k/include/uapi/asm/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)
 
diff --git a/arch/m68k/virt/config.c b/arch/m68k/virt/config.c
index 632ba200ad42..ad71af8273ec 100644
--- a/arch/m68k/virt/config.c
+++ b/arch/m68k/virt/config.c
@@ -2,6 +2,7 @@
 
 #include <linux/reboot.h>
 #include <linux/serial_core.h>
+#include <linux/random.h>
 #include <clocksource/timer-goldfish.h>
 
 #include <asm/bootinfo.h>
@@ -92,6 +93,9 @@ int __init virt_parse_bootinfo(const struct bi_record *record)
 		data += 4;
 		virt_bi_data.virtio.irq = be32_to_cpup(data);
 		break;
+	case BI_VIRT_RNG_SEED:
+		add_bootloader_randomness(data + 4, be32_to_cpup(data));
+		break;
 	default:
 		unknown = 1;
 		break;
-- 
2.35.1