[PATCH v7 04/20] KVM: selftests: Initialize the default/global pRNG during kvm_selftest_init()

[Sean Christopherson]

Initialize the default kvm_rng during selftest initialization so that the
pRNG can be used by tests before creating a VM.  As pointed out by Sashiko,
failure to actually initialize the generate makes it decidedly not random.

Signed-off-by: Sean Christopherson <seanjc at google.com>
---
 tools/testing/selftests/kvm/lib/kvm_util.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 875030c22d07..1016865d3f7a 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -24,6 +24,13 @@ u32 kvm_random_seed;
 struct kvm_random_state kvm_rng;
 static u32 last_kvm_seed;
 
+static void kvm_seed_rng(u32 seed)
+{
+	kvm_random_seed = last_kvm_seed = seed;
+	pr_info("Random seed: 0x%x\n", kvm_random_seed);
+	kvm_rng = new_kvm_random_state(kvm_random_seed);
+}
+
 static size_t vcpu_mmap_sz(void);
 
 int __open_path_or_exit(const char *path, int flags, const char *enoent_help)
@@ -515,11 +522,9 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus,
 	slot0 = memslot2region(vm, 0);
 	ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size);
 
-	if (kvm_random_seed != last_kvm_seed) {
-		pr_info("Random seed: 0x%x\n", kvm_random_seed);
-		last_kvm_seed = kvm_random_seed;
-	}
-	kvm_rng = new_kvm_random_state(kvm_random_seed);
+	if (kvm_random_seed != last_kvm_seed)
+		kvm_seed_rng(kvm_random_seed);
+
 	sync_global_to_guest(vm, kvm_rng);
 
 	kvm_arch_vm_post_create(vm, nr_runnable_vcpus);
@@ -2279,8 +2284,7 @@ void __attribute((constructor)) kvm_selftest_init(void)
 	sigaction(SIGILL, &sig_sa, NULL);
 	sigaction(SIGFPE, &sig_sa, NULL);
 
-	kvm_random_seed = last_kvm_seed = random();
-	pr_info("Random seed: 0x%x\n", kvm_random_seed);
+	kvm_seed_rng(random());
 
 	kvm_selftest_arch_init();
 }
-- 
2.54.0.1136.gdb2ca164c4-goog