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From: Oliver Upton To: Sean Christopherson Cc: Marc Zyngier , James Morse , Alexandru Elisei , Paolo Bonzini , Shuah Khan , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-kselftest@vger.kernel.org, David Matlack , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 1/2] KVM: selftests: Allow >1 guest mode in access_tracking_perf_test Message-ID: References: <20221111231946.944807-1-oliver.upton@linux.dev> <20221111231946.944807-2-oliver.upton@linux.dev> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221114_135733_340412_1EE6D5DA X-CRM114-Status: GOOD ( 31.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Nov 14, 2022 at 05:12:48PM +0000, Sean Christopherson wrote: > On Fri, Nov 11, 2022, Oliver Upton wrote: > > As the name implies, for_each_guest_mode() will run the test case for > > all supported guest addressing modes. On x86 that doesn't amount to > > anything, but arm64 can handle 4K, 16K, and 64K page sizes on supporting > > hardware. > > > > Blindly attempting to run access_tracking_perf_test on arm64 stalls on > > the second test case, as the 'done' global remains set between test > > iterations. Clear it after VM teardown in anticipation of a subsequent > > test case. > > > > Signed-off-by: Oliver Upton > > --- > > tools/testing/selftests/kvm/access_tracking_perf_test.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c > > index 76c583a07ea2..4da066479e0a 100644 > > --- a/tools/testing/selftests/kvm/access_tracking_perf_test.c > > +++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c > > @@ -326,6 +326,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) > > > > perf_test_join_vcpu_threads(nr_vcpus); > > perf_test_destroy_vm(vm); > > + > > + /* Clear done in anticipation of testing another guest mode */ > > + done = false; > > Can we fix this in the so called "perf_test" infrastructure? > memslot_modification_stress_test.c has the same bug just inverted (see run_vcpus). Yeah, sounds good to me. I'll wrap your diff up in a patch here in a bit. -- Thanks, Oliver > --- > .../selftests/kvm/access_tracking_perf_test.c | 28 +++++-------------- > .../selftests/kvm/include/perf_test_util.h | 3 ++ > .../selftests/kvm/lib/perf_test_util.c | 3 ++ > .../kvm/memslot_modification_stress_test.c | 6 +--- > 4 files changed, 14 insertions(+), 26 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..786bc62a2c79 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]; > > @@ -206,28 +203,20 @@ static void assert_ucall(struct kvm_vcpu *vcpu, uint64_t expected_ucall) > expected_ucall, actual_ucall); > } > > -static bool spin_wait_for_next_iteration(int *current_iteration) > -{ > - int last_iteration = *current_iteration; > - > - do { > - if (READ_ONCE(done)) > - return false; > - > - *current_iteration = READ_ONCE(iteration); > - } while (last_iteration == *current_iteration); > - > - return true; > -} > - > static void vcpu_thread_main(struct perf_test_vcpu_args *vcpu_args) > { > struct kvm_vcpu *vcpu = vcpu_args->vcpu; > struct kvm_vm *vm = perf_test_args.vm; > int vcpu_idx = vcpu_args->vcpu_idx; > int current_iteration = 0; > + int last_iteration; > + > + while (!READ_ONCE(perf_test_args.stop_vcpus)) { > + last_iteration = current_iteration; > + do { > + current_iteration = READ_ONCE(iteration); > + } while (current_iteration == last_iteration); > > - while (spin_wait_for_next_iteration(¤t_iteration)) { > switch (READ_ONCE(iteration_work)) { > case ITERATION_ACCESS_MEMORY: > vcpu_run(vcpu); > @@ -321,9 +310,6 @@ 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); > } > diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h > index eaa88df0555a..536d7c3c3f14 100644 > --- a/tools/testing/selftests/kvm/include/perf_test_util.h > +++ b/tools/testing/selftests/kvm/include/perf_test_util.h > @@ -40,6 +40,9 @@ struct perf_test_args { > /* Run vCPUs in L2 instead of L1, if the architecture supports it. */ > bool nested; > > + /* Test is done, stop running vCPUs. */ > + bool stop_vcpus; > + > struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS]; > }; > > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > index 9618b37c66f7..ee3f499ccbd2 100644 > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > @@ -267,6 +267,7 @@ void perf_test_start_vcpu_threads(int nr_vcpus, > > vcpu_thread_fn = vcpu_fn; > WRITE_ONCE(all_vcpu_threads_running, false); > + WRITE_ONCE(perf_test_args.stop_vcpus, false); > > for (i = 0; i < nr_vcpus; i++) { > struct vcpu_thread *vcpu = &vcpu_threads[i]; > @@ -289,6 +290,8 @@ void perf_test_join_vcpu_threads(int nr_vcpus) > { > int i; > > + WRITE_ONCE(perf_test_args.stop_vcpus, true); > + > for (i = 0; i < nr_vcpus; i++) > pthread_join(vcpu_threads[i].thread, NULL); > } > diff --git a/tools/testing/selftests/kvm/memslot_modification_stress_test.c b/tools/testing/selftests/kvm/memslot_modification_stress_test.c > index bb1d17a1171b..3a5e4518307c 100644 > --- a/tools/testing/selftests/kvm/memslot_modification_stress_test.c > +++ b/tools/testing/selftests/kvm/memslot_modification_stress_test.c > @@ -34,8 +34,6 @@ > static int nr_vcpus = 1; > static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE; > > -static bool run_vcpus = true; > - > static void vcpu_worker(struct perf_test_vcpu_args *vcpu_args) > { > struct kvm_vcpu *vcpu = vcpu_args->vcpu; > @@ -45,7 +43,7 @@ static void vcpu_worker(struct perf_test_vcpu_args *vcpu_args) > run = vcpu->run; > > /* Let the guest access its memory until a stop signal is received */ > - while (READ_ONCE(run_vcpus)) { > + while (!READ_ONCE(perf_test_args.stop_vcpus)) { > ret = _vcpu_run(vcpu); > TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret); > > @@ -110,8 +108,6 @@ static void run_test(enum vm_guest_mode mode, void *arg) > add_remove_memslot(vm, p->memslot_modification_delay, > p->nr_memslot_modifications); > > - run_vcpus = false; > - > perf_test_join_vcpu_threads(nr_vcpus); > pr_info("All vCPU threads joined\n"); > > > base-commit: 10dbc57b5777e6938a648eb4a870bad448fcb6f5 > -- > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel