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[PATCH] hw/i386: pass RNG seed to e820 setup table
From: |
Jason A. Donenfeld |
Subject: |
[PATCH] hw/i386: pass RNG seed to e820 setup table |
Date: |
Thu, 30 Jun 2022 13:37:17 +0200 |
Tiny machines optimized for fast boot time generally don't use EFI,
which means a random seed has to be supplied some other way, in this
case by the e820 setup table, which supplies a place for one. This
commit adds passing this random seed via the table. It is confirmed to
be working with the Linux patch in the link.
Link: https://lore.kernel.org/lkml/20220630113300.1892799-1-Jason@zx2c4.com/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
hw/i386/x86.c | 19 ++++++++++++++-----
include/standard-headers/asm-x86/bootparam.h | 1 +
2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/hw/i386/x86.c b/hw/i386/x86.c
index 6003b4b2df..0724759eec 100644
--- a/hw/i386/x86.c
+++ b/hw/i386/x86.c
@@ -26,6 +26,7 @@
#include "qemu/cutils.h"
#include "qemu/units.h"
#include "qemu/datadir.h"
+#include "qemu/guest-random.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
#include "qapi/qapi-visit-common.h"
@@ -1045,6 +1046,16 @@ void x86_load_linux(X86MachineState *x86ms,
}
fclose(f);
+ setup_data_offset = QEMU_ALIGN_UP(kernel_size, 16);
+ kernel_size = setup_data_offset + sizeof(struct setup_data) + 32;
+ kernel = g_realloc(kernel, kernel_size);
+ stq_p(header + 0x250, prot_addr + setup_data_offset);
+ setup_data = (struct setup_data *)(kernel + setup_data_offset);
+ setup_data->next = 0;
+ setup_data->type = cpu_to_le32(SETUP_RNG_SEED);
+ setup_data->len = cpu_to_le32(32);
+ qemu_guest_getrandom_nofail(setup_data->data, 32);
+
/* append dtb to kernel */
if (dtb_filename) {
if (protocol < 0x209) {
@@ -1059,13 +1070,11 @@ void x86_load_linux(X86MachineState *x86ms,
exit(1);
}
- setup_data_offset = QEMU_ALIGN_UP(kernel_size, 16);
- kernel_size = setup_data_offset + sizeof(struct setup_data) + dtb_size;
+ kernel_size += sizeof(struct setup_data) + dtb_size;
kernel = g_realloc(kernel, kernel_size);
- stq_p(header + 0x250, prot_addr + setup_data_offset);
-
- setup_data = (struct setup_data *)(kernel + setup_data_offset);
+ setup_data->next = prot_addr + setup_data_offset + sizeof(*setup_data)
+ setup_data->len;
+ ++setup_data;
setup_data->next = 0;
setup_data->type = cpu_to_le32(SETUP_DTB);
setup_data->len = cpu_to_le32(dtb_size);
diff --git a/include/standard-headers/asm-x86/bootparam.h
b/include/standard-headers/asm-x86/bootparam.h
index 072e2ed546..b8cb1fa313 100644
--- a/include/standard-headers/asm-x86/bootparam.h
+++ b/include/standard-headers/asm-x86/bootparam.h
@@ -10,6 +10,7 @@
#define SETUP_EFI 4
#define SETUP_APPLE_PROPERTIES 5
#define SETUP_JAILHOUSE 6
+#define SETUP_RNG_SEED 8
#define SETUP_INDIRECT (1<<31)
--
2.35.1
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