From b31f21a7e97eee501db86714868d84377e68e4df Mon Sep 17 00:00:00 2001 From: Colton Lewis Date: Mon, 7 Nov 2022 18:22:05 +0000 Subject: [PATCH] KVM: selftests: implement random number generator for guest code Implement random number generator for guest code to randomize parts of the test, making it less predictable and a more accurate reflection of reality. The random number generator chosen is the Park-Miller Linear Congruential Generator, a fancy name for a basic and well-understood random number generator entirely sufficient for this purpose. Signed-off-by: Colton Lewis Reviewed-by: Sean Christopherson Reviewed-by: David Matlack Link: https://lore.kernel.org/r/20221107182208.479157-2-coltonlewis@google.com Signed-off-by: Sean Christopherson --- tools/testing/selftests/kvm/include/test_util.h | 7 +++++++ tools/testing/selftests/kvm/lib/test_util.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h index 3be98e81189a7..80d6416f3012e 100644 --- a/tools/testing/selftests/kvm/include/test_util.h +++ b/tools/testing/selftests/kvm/include/test_util.h @@ -77,6 +77,13 @@ struct timespec timespec_sub(struct timespec ts1, struct timespec ts2); struct timespec timespec_elapsed(struct timespec start); struct timespec timespec_div(struct timespec ts, int divisor); +struct guest_random_state { + uint32_t seed; +}; + +struct guest_random_state new_guest_random_state(uint32_t seed); +uint32_t guest_random_u32(struct guest_random_state *state); + enum vm_mem_backing_src_type { VM_MEM_SRC_ANONYMOUS, VM_MEM_SRC_ANONYMOUS_THP, diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c index c2d9c68277793..5c22fa4c2825e 100644 --- a/tools/testing/selftests/kvm/lib/test_util.c +++ b/tools/testing/selftests/kvm/lib/test_util.c @@ -17,6 +17,23 @@ #include "test_util.h" +/* + * Random number generator that is usable from guest code. This is the + * Park-Miller LCG using standard constants. + */ + +struct guest_random_state new_guest_random_state(uint32_t seed) +{ + struct guest_random_state s = {.seed = seed}; + return s; +} + +uint32_t guest_random_u32(struct guest_random_state *state) +{ + state->seed = (uint64_t)state->seed * 48271 % ((uint32_t)(1 << 31) - 1); + return state->seed; +} + /* * Parses "[0-9]+[kmgt]?". */ -- 2.30.2