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| author | Sean Christopherson <seanjc@google.com> | 2024-03-14 21:54:54 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-04-29 22:50:41 +0300 |
| commit | cb6c6914788f65efc8efa72b8a582e2aa2ccc386 (patch) | |
| tree | ccaf205443f73001cb70b6c3b8ca3c47b68733d0 /tools/testing/selftests/kvm/include | |
| parent | 730cfa45b5f4f170095707b526dc7af99c9f0959 (diff) | |
| download | linux-cb6c6914788f65efc8efa72b8a582e2aa2ccc386.tar.xz | |
KVM: selftests: Provide a global pseudo-RNG instance for all tests
Add a global guest_random_state instance, i.e. a pseudo-RNG, so that an
RNG is available for *all* tests. This will allow randomizing behavior
in core library code, e.g. x86 will utilize the pRNG to conditionally
force emulation of writes from within common guest code.
To allow for deterministic runs, and to be compatible with existing tests,
allow tests to override the seed used to initialize the pRNG.
Note, the seed *must* be overwritten before a VM is created in order for
the seed to take effect, though it's perfectly fine for a test to
initialize multiple VMs with different seeds.
And as evidenced by memstress_guest_code(), it's also a-ok to instantiate
more RNGs using the global seed (or a modified version of it). The goal
of the global RNG is purely to ensure that _a_ source of random numbers is
available, it doesn't have to be the _only_ RNG.
Link: https://lore.kernel.org/r/20240314185459.2439072-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'tools/testing/selftests/kvm/include')
| -rw-r--r-- | tools/testing/selftests/kvm/include/memstress.h | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/include/test_util.h | 8 |
2 files changed, 8 insertions, 1 deletions
diff --git a/tools/testing/selftests/kvm/include/memstress.h b/tools/testing/selftests/kvm/include/memstress.h index ce4e603050ea..9071eb6dea60 100644 --- a/tools/testing/selftests/kvm/include/memstress.h +++ b/tools/testing/selftests/kvm/include/memstress.h @@ -62,7 +62,6 @@ struct kvm_vm *memstress_create_vm(enum vm_guest_mode mode, int nr_vcpus, void memstress_destroy_vm(struct kvm_vm *vm); void memstress_set_write_percent(struct kvm_vm *vm, uint32_t write_percent); -void memstress_set_random_seed(struct kvm_vm *vm, uint32_t random_seed); void memstress_set_random_access(struct kvm_vm *vm, bool random_access); void memstress_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct memstress_vcpu_args *)); diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h index 8a6e30612c86..4b78fb7e539e 100644 --- a/tools/testing/selftests/kvm/include/test_util.h +++ b/tools/testing/selftests/kvm/include/test_util.h @@ -91,9 +91,17 @@ struct guest_random_state { uint32_t seed; }; +extern uint32_t guest_random_seed; +extern struct guest_random_state guest_rng; + struct guest_random_state new_guest_random_state(uint32_t seed); uint32_t guest_random_u32(struct guest_random_state *state); +static inline uint64_t guest_random_u64(struct guest_random_state *state) +{ + return ((uint64_t)guest_random_u32(state) << 32) | guest_random_u32(state); +} + enum vm_mem_backing_src_type { VM_MEM_SRC_ANONYMOUS, VM_MEM_SRC_ANONYMOUS_THP, |