KVM: selftests: Have perf_test_util signal when to stop vCPUs

Signal that a test run is complete through perf_test_args instead of
having tests open code a similar solution. Ensure that the field resets
to false at the beginning of a test run as the structure is reused
between test runs, eliminating a couple of bugs:

access_tracking_perf_test hangs indefinitely on a subsequent test run,
as 'done' remains true. The bug doesn't amount to much right now, as x86
supports a single guest mode. However, this is a precondition of
enabling the test for other architectures with >1 guest mode, like
arm64.

memslot_modification_stress_test has the exact opposite problem, where
subsequent test runs complete immediately as 'run_vcpus' remains false.

Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
[oliver: added commit message, preserve spin_wait_for_next_iteration()]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221118211503.4049023-2-oliver.upton@linux.dev

1 files changed, 1 insertions, 7 deletions

diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
index 76c583a07ea2..942370d57392 100644
--- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
+++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
@@ -58,9 +58,6 @@ static enum {
 	ITERATION_MARK_IDLE,
 } iteration_work;
 
-/* Set to true when vCPU threads should exit. */
-static bool done;
-
 /* The iteration that was last completed by each vCPU. */
 static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
 
@@ -211,7 +208,7 @@ static bool spin_wait_for_next_iteration(int *current_iteration)
 	int last_iteration = *current_iteration;
 
 	do {
-		if (READ_ONCE(done))
+		if (READ_ONCE(perf_test_args.stop_vcpus))
 			return false;
 
 		*current_iteration = READ_ONCE(iteration);
@@ -321,9 +318,6 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	mark_memory_idle(vm, nr_vcpus);
 	access_memory(vm, nr_vcpus, ACCESS_READ, "Reading from idle memory");
 
-	/* Set done to signal the vCPU threads to exit */
-	done = true;
-
 	perf_test_join_vcpu_threads(nr_vcpus);
 	perf_test_destroy_vm(vm);
 }