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Fri, 25 Nov 2022 14:46:51 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 237CAA4054; Fri, 25 Nov 2022 14:46:51 +0000 (GMT) Received: from p-imbrenda (unknown [9.171.0.125]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with SMTP; Fri, 25 Nov 2022 14:46:51 +0000 (GMT) Date: Fri, 25 Nov 2022 15:46:46 +0100 From: Claudio Imbrenda To: Nico Boehr Cc: kvm@vger.kernel.org, frankja@linux.ibm.com, thuth@redhat.com Subject: Re: [kvm-unit-tests PATCH v2 2/2] s390x: add CMM test during migration Message-ID: <20221125154646.5974cb52@p-imbrenda> In-Reply-To: <20221124134429.612467-3-nrb@linux.ibm.com> References: <20221124134429.612467-1-nrb@linux.ibm.com> <20221124134429.612467-3-nrb@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.1.1 (GTK 3.24.34; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: jCmqG3ZnIHvEjo6idov0k2WouHpat-A4 X-Proofpoint-ORIG-GUID: R9oK38rRflohWcygGZmeGTHxrfiRqDWG X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-25_06,2022-11-25_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 mlxlogscore=999 phishscore=0 priorityscore=1501 clxscore=1015 suspectscore=0 bulkscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211250114 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 24 Nov 2022 14:44:29 +0100 Nico Boehr wrote: > Add a test which modifies CMM page states while migration is in > progress. > > Signed-off-by: Nico Boehr > --- > s390x/Makefile | 1 + > s390x/migration-during-cmm.c | 121 +++++++++++++++++++++++++++++++++++ > s390x/unittests.cfg | 5 ++ > 3 files changed, 127 insertions(+) > create mode 100644 s390x/migration-during-cmm.c > > diff --git a/s390x/Makefile b/s390x/Makefile > index 401cb6371cee..64c7c04409ae 100644 > --- a/s390x/Makefile > +++ b/s390x/Makefile > @@ -39,6 +39,7 @@ tests += $(TEST_DIR)/panic-loop-extint.elf > tests += $(TEST_DIR)/panic-loop-pgm.elf > tests += $(TEST_DIR)/migration-sck.elf > tests += $(TEST_DIR)/exittime.elf > +tests += $(TEST_DIR)/migration-during-cmm.elf > > pv-tests += $(TEST_DIR)/pv-diags.elf > > diff --git a/s390x/migration-during-cmm.c b/s390x/migration-during-cmm.c > new file mode 100644 > index 000000000000..afe1f73605ba > --- /dev/null > +++ b/s390x/migration-during-cmm.c > @@ -0,0 +1,121 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Perform CMMA actions while migrating. > + * > + * Copyright IBM Corp. 2022 > + * > + * Authors: > + * Nico Boehr > + */ > + > +#include > +#include > +#include > + > +#include "cmm.h" > + > +#define NUM_PAGES 128 > + > +/* > + * Allocate 3 pages more than we need so we can start at different offsets. This ensures page states > + * change on every loop iteration. > + */ > +static uint8_t pagebuf[(NUM_PAGES + 3) * PAGE_SIZE] __attribute__((aligned(PAGE_SIZE))); > + > +static unsigned int thread_iters; > +static int thread_should_exit; > +static int thread_exited; > +struct cmm_verify_result result; > + > +static void test_cmm_during_migration(void) > +{ > + uint8_t *pagebuf_start; > + /* > + * The second CPU must not print on the console, otherwise it will race with > + * the primary CPU on the SCLP buffer. > + */ > + while (!thread_should_exit) { I don't see any mb()s here, maybe use READ_ONCE > + /* > + * Start on a offset different from the last iteration so page states change with > + * every iteration. This is why pagebuf has 3 extra pages. > + */ > + pagebuf_start = pagebuf + (thread_iters % 4) * PAGE_SIZE; > + cmm_set_page_states(pagebuf_start, NUM_PAGES); > + > + /* > + * Always increment even if the verify fails. This ensures primary CPU knows where > + * we left off and can do an additional verify round after migration finished. > + */ > + thread_iters++; > + > + result = cmm_verify_page_states(pagebuf_start, NUM_PAGES); > + if (result.verify_failed) > + goto out; > + } > + > +out: > + WRITE_ONCE(thread_exited, 1); > +} > + > +int main(void) > +{ > + bool has_essa = check_essa_available(); > + struct psw psw; > + > + report_prefix_push("migration-during-cmm"); > + if (!has_essa) { > + report_skip("ESSA is not available"); > + goto error; > + } > + > + if (smp_query_num_cpus() == 1) { > + report_skip("need at least 2 cpus for this test"); > + goto error; > + } > + > + psw.mask = extract_psw_mask(); > + psw.addr = (unsigned long)test_cmm_during_migration; > + smp_cpu_setup(1, psw); > + > + puts("Please migrate me, then press return\n"); > + (void)getchar(); > + > + WRITE_ONCE(thread_should_exit, 1); > + > + while (!thread_exited) > + mb(); > + > + report_info("thread completed %u iterations", thread_iters); > + > + report_prefix_push("during migration"); > + cmm_report_verify(&result); > + report_prefix_pop(); > + > + /* > + * Verification of page states occurs on the thread. We don't know if we > + * were still migrating during the verification. > + * To be sure, make another verification round after the migration > + * finished to catch page states which might not have been migrated > + * correctly. > + */ > + report_prefix_push("after migration"); > + assert(thread_iters > 0); > + result = cmm_verify_page_states(pagebuf + ((thread_iters - 1) % 4) * PAGE_SIZE, NUM_PAGES); > + cmm_report_verify(&result); > + report_prefix_pop(); > + > + goto done; > + > +error: > + /* > + * If we just exit and don't ask migrate_cmd to migrate us, it > + * will just hang forever. Hence, also ask for migration when we > + * skip this test alltogether. > + */ > + puts("Please migrate me, then press return\n"); > + (void)getchar(); > + I wonder if this can be made easier to review and less error prone... maybe something like: static void migrate_once(void) { static bool migrated = false; if (migrated) return; puts("Please migrate me, then press return\n"); migrated = true; (void)getchar(); } then you can put it where needed in the code _and_ unconditionally at the end > +done: > + report_prefix_pop(); > + return report_summary(); > +} > diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg > index 3caf81eda396..f6889bd4da01 100644 > --- a/s390x/unittests.cfg > +++ b/s390x/unittests.cfg > @@ -208,3 +208,8 @@ groups = migration > [exittime] > file = exittime.elf > smp = 2 > + > +[migration-during-cmm] > +file = migration-during-cmm.elf > +groups = migration > +smp = 2