@@ -387,8 +387,7 @@ static void dirty_ring_after_vcpu_run(struct kvm_vcpu *vcpu)
/* A ucall-sync or ring-full event is allowed */
if (get_ucall(vcpu, NULL) == UCALL_SYNC) {
- /* We should allow this to continue */
- ;
+ vcpu_handle_sync_stop();
} else if (run->exit_reason == KVM_EXIT_DIRTY_RING_FULL) {
/* Update the flag first before pause */
WRITE_ONCE(dirty_ring_vcpu_ring_full, true);
@@ -697,6 +696,15 @@ static void run_test(enum vm_guest_mode mode, void *arg)
#ifdef __s390x__
/* Align to 1M (segment size) */
guest_test_phys_mem = align_down(guest_test_phys_mem, 1 << 20);
+
+ /*
+ * The workaround in guest_code() to write all pages prior to the first
+ * iteration isn't compatible with the dirty ring, as the dirty ring
+ * support relies on the vCPU to actually stop when vcpu_stop is set so
+ * that the vCPU doesn't hang waiting for the dirty ring to be emptied.
+ */
+ TEST_ASSERT(host_log_mode != LOG_MODE_DIRTY_RING,
+ "Test needs to be updated to support s390 dirty ring");
#endif
pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
Now that the vCPU doesn't dirty every page on the first iteration for architectures that support the dirty ring, honor vcpu_stop in the dirty ring's vCPU worker, i.e. stop when the main thread says "stop". This will allow plumbing vcpu_stop into the guest so that the vCPU doesn't need to periodically exit to userspace just to see if it should stop. Add a comment explaining that marking all pages as dirty is problematic for the dirty ring, as it results in the guest getting stuck on "ring full". This could be addressed by adding a GUEST_SYNC() in that initial loop, but it's not clear how that would interact with s390's behavior. Signed-off-by: Sean Christopherson <seanjc@google.com> --- tools/testing/selftests/kvm/dirty_log_test.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)