[Qemu-devel] [PATCH v3 10/23] cpus: Initialize pseudo-random seeds for all guest cpus

[Richard Henderson]

When the -seed option is given, call qemu_guest_random_seed_main,
putting the subsystem into deterministic mode.  Pass derived seeds
to each cpu created; which is a no-op unless the subsystem is in
deterministic mode.

Cc: Daniel P. Berrangé <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
 include/qom/cpu.h |  1 +
 cpus.c            |  9 +++++++++
 vl.c              |  4 ++++
 qemu-options.hx   | 10 ++++++++++
 4 files changed, 24 insertions(+)

diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 1d6099e5d4..343cc6d51e 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -372,6 +372,7 @@ struct CPUState {
     int singlestep_enabled;
     int64_t icount_budget;
     int64_t icount_extra;
+    uint64_t random_seed;
     sigjmp_buf jmp_env;
 
     QemuMutex work_mutex;
diff --git a/cpus.c b/cpus.c
index e83f72b48b..6d88f6bfcd 100644
--- a/cpus.c
+++ b/cpus.c
@@ -49,6 +49,7 @@
 #include "qemu/option.h"
 #include "qemu/bitmap.h"
 #include "qemu/seqlock.h"
+#include "qemu/guest-random.h"
 #include "tcg.h"
 #include "hw/nmi.h"
 #include "sysemu/replay.h"
@@ -1275,6 +1276,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
     /* signal CPU creation */
     cpu->created = true;
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
         if (cpu_can_run(cpu)) {
@@ -1318,6 +1320,7 @@ static void *qemu_dummy_cpu_thread_fn(void *arg)
     /* signal CPU creation */
     cpu->created = true;
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
         qemu_mutex_unlock_iothread();
@@ -1477,6 +1480,7 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
     cpu->created = true;
     cpu->can_do_io = 1;
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     /* wait for initial kick-off after machine start */
     while (first_cpu->stopped) {
@@ -1591,6 +1595,7 @@ static void *qemu_hax_cpu_thread_fn(void *arg)
 
     hax_init_vcpu(cpu);
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
         if (cpu_can_run(cpu)) {
@@ -1630,6 +1635,7 @@ static void *qemu_hvf_cpu_thread_fn(void *arg)
     /* signal CPU creation */
     cpu->created = true;
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
         if (cpu_can_run(cpu)) {
@@ -1670,6 +1676,7 @@ static void *qemu_whpx_cpu_thread_fn(void *arg)
     /* signal CPU creation */
     cpu->created = true;
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     do {
         if (cpu_can_run(cpu)) {
@@ -1723,6 +1730,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
     cpu->can_do_io = 1;
     current_cpu = cpu;
     qemu_cond_signal(&qemu_cpu_cond);
+    qemu_guest_random_seed_thread_part2(cpu->random_seed);
 
     /* process any pending work */
     cpu->exit_request = 1;
@@ -2070,6 +2078,7 @@ void qemu_init_vcpu(CPUState *cpu)
     cpu->nr_cores = smp_cores;
     cpu->nr_threads = smp_threads;
     cpu->stopped = true;
+    cpu->random_seed = qemu_guest_random_seed_thread_part1();
 
     if (!cpu->as) {
         /* If the target cpu hasn't set up any address spaces itself,
diff --git a/vl.c b/vl.c
index c1d5484e12..d84f883c2c 100644
--- a/vl.c
+++ b/vl.c
@@ -128,6 +128,7 @@ int main(int argc, char **argv)
 #include "qapi/qapi-commands-ui.h"
 #include "qapi/qmp/qerror.h"
 #include "sysemu/iothread.h"
+#include "qemu/guest-random.h"
 
 #define MAX_VIRTIO_CONSOLES 1
 
@@ -3330,6 +3331,9 @@ int main(int argc, char **argv, char **envp)
             case QEMU_OPTION_DFILTER:
                 qemu_set_dfilter_ranges(optarg, &error_fatal);
                 break;
+            case QEMU_OPTION_seed:
+                qemu_guest_random_seed_main(optarg, &error_fatal);
+                break;
             case QEMU_OPTION_s:
                 add_device_config(DEV_GDB, "tcp::" DEFAULT_GDBSTUB_PORT);
                 break;
diff --git a/qemu-options.hx b/qemu-options.hx
index 08749a3391..b8da998668 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3601,6 +3601,16 @@ the 0x200 sized block starting at 0xffffffc000080000 and 
another 0x1000 sized
 block starting at 0xffffffc00005f000.
 ETEXI
 
+DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
+    "-seed number       seed the pseudo-random number generator\n",
+    QEMU_ARCH_ALL)
+STEXI
address@hidden -seed @var{number}
address@hidden -seed
+Force the guest to use a deterministic pseudo-random number generator, seeded
+with @var{number}.  This does not affect crypto routines within the host.
+ETEXI
+
 DEF("L", HAS_ARG, QEMU_OPTION_L, \
     "-L path         set the directory for the BIOS, VGA BIOS and keymaps\n",
     QEMU_ARCH_ALL)
-- 
2.17.2