Commit b31f21a7 authored by Colton Lewis's avatar Colton Lewis Committed by Sean Christopherson
Browse files

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: default avatarColton Lewis <coltonlewis@google.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20221107182208.479157-2-coltonlewis@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent d886724e

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

+7 −0
Original line number Diff line number Diff line
@@ -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,

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

+17 −0
Original line number Diff line number Diff line
@@ -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]?".

 */