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/20220708113907.891319-1-ja...@zx2c4.com/ Signed-off-by: Jason A. Donenfeld <ja...@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..b2aaad10e5 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 9 #define SETUP_INDIRECT (1<<31) -- 2.35.1