Commit 73369acd authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Provide an API for getting a random bool from an RNG 

Move memstress' random bool logic into common code to avoid reinventing
the wheel for basic yes/no decisions.  Provide an outer wrapper to handle
the basic/common case of just wanting a 50/50 chance of something
happening.

Link: https://lore.kernel.org/r/20240314185459.2439072-3-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent cb6c6914

tools/testing/selftests/kvm/include/test_util.h

+11 −0
Original line number Diff line number Diff line
@@ -97,6 +97,17 @@ 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 bool __guest_random_bool(struct guest_random_state *state,

				       uint8_t percent)

{

	return (guest_random_u32(state) % 100) < percent;

}



static inline bool guest_random_bool(struct guest_random_state *state)

{

	return __guest_random_bool(state, 50);

}



static inline uint64_t guest_random_u64(struct guest_random_state *state)

{

	return ((uint64_t)guest_random_u32(state) << 32) | guest_random_u32(state);

tools/testing/selftests/kvm/lib/memstress.c

+1 −1
Original line number Diff line number Diff line
@@ -74,7 +74,7 @@ void memstress_guest_code(uint32_t vcpu_idx) 


			addr = gva + (page * args->guest_page_size);



			if (guest_random_u32(&rand_state) % 100 < args->write_percent)

			if (__guest_random_bool(&rand_state, args->write_percent))

				*(uint64_t *)addr = 0x0123456789ABCDEF;

			else

				READ_ONCE(*(uint64_t *)addr);