On Wed, 14 Dec 2022 14:55:35 +0100
Nico Boehr <nrb@xxxxxxxxxxxxx> wrote:
> Right now, we have a test which sets storage keys, then migrates the VM
> and - after migration finished - verifies the skeys are still there.
>
> Add a new version of the test which changes storage keys while the
> migration is in progress. This is achieved by adding a command line
> argument to the existing migration-skey test.
>
> Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> ---
> s390x/migration-skey.c | 218 +++++++++++++++++++++++++++++++++++++----
> s390x/unittests.cfg | 15 ++-
> 2 files changed, 210 insertions(+), 23 deletions(-)
>
> diff --git a/s390x/migration-skey.c b/s390x/migration-skey.c
> index a91eb6b5a63e..3c4131810a16 100644
> --- a/s390x/migration-skey.c
> +++ b/s390x/migration-skey.c
> @@ -2,6 +2,12 @@
> /*
> * Storage Key migration tests
> *
> + * There are two variants of this test:
> + * - sequential: set storage keys on some pages, migrates the VM and then
> + * verifies that the storage keys are still as we expect.
> + * - parallel: start migration and set and check storage keys on some
> + * pages while migration is in process.
> + *
> * Copyright IBM Corp. 2022
> *
> * Authors:
> @@ -13,16 +19,45 @@
> #include <asm/facility.h>
> #include <asm/page.h>
> #include <asm/mem.h>
> -#include <asm/interrupt.h>
> +#include <asm/barrier.h>
> #include <hardware.h>
> +#include <smp.h>
> +
> +struct verify_result {
> + bool verify_failed;
> + union skey expected_key;
> + union skey actual_key;
> + unsigned long page_mismatch_idx;
> + unsigned long page_mismatch_addr;
> +};
>
> #define NUM_PAGES 128
> -static uint8_t pagebuf[NUM_PAGES][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
> +static uint8_t pagebuf[NUM_PAGES * PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
> +
> +static struct verify_result result;
> +
> +static unsigned int thread_iters;
> +static bool thread_should_exit;
> +static bool thread_exited;
> +
> +static enum {
> + TEST_INVALID,
> + TEST_SEQUENTIAL,
> + TEST_PARALLEL
> +} arg_test_to_run;
>
> -static void test_migration(void)
> +/*
> + * Set storage key test pattern on pagebuf with a seed for the storage keys.
> + *
> + * Each page's storage key is generated by taking the page's index in pagebuf,
> + * XOR-ing that with the given seed and then multipling the result with two.
> + *
> + * Only the lower seven bits of the seed are considered.
> + */
> +static void set_test_pattern(unsigned char seed)
> {
> - union skey expected_key, actual_key;
> - int i, key_to_set, key_mismatches = 0;
> + unsigned char key_to_set;
> + unsigned long i;
>
> for (i = 0; i < NUM_PAGES; i++) {
> /*
> @@ -32,15 +67,34 @@ static void test_migration(void)
> * protection as well as reference and change indication for
> * some keys.
> */
> - key_to_set = i * 2;
> - set_storage_key(pagebuf[i], key_to_set, 1);
> + key_to_set = (i ^ seed) * 2;
> + set_storage_key(pagebuf + i * PAGE_SIZE, key_to_set, 1);
> }
> +}
>
> - migrate_once();
> +/*
> + * Verify storage keys on pagebuf.
> + * Storage keys must have been set by set_test_pattern on pagebuf before.
> + * set_test_pattern must have been called with the same seed value.
> + *
> + * If storage keys match the expected result, will return a verify_result
> + * with verify_failed false. All other fields are then invalid.
> + * If there is a mismatch, returned struct will have verify_failed true and will
> + * be filled with the details on the first mismatch encountered.
> + */
> +static struct verify_result verify_test_pattern(unsigned char seed)
> +{
> + union skey expected_key, actual_key;
> + struct verify_result result = {
> + .verify_failed = true
> + };
> + uint8_t *cur_page;
> + unsigned long i;
>
> for (i = 0; i < NUM_PAGES; i++) {
> - actual_key.val = get_storage_key(pagebuf[i]);
> - expected_key.val = i * 2;
> + cur_page = pagebuf + i * PAGE_SIZE;
> + actual_key.val = get_storage_key(cur_page);
> + expected_key.val = (i ^ seed) * 2;
>
> /*
> * The PoP neither gives a guarantee that the reference bit is
> @@ -51,27 +105,153 @@ static void test_migration(void)
> actual_key.str.rf = 0;
> expected_key.str.rf = 0;
>
> - /* don't log anything when key matches to avoid spamming the log */
> if (actual_key.val != expected_key.val) {
> - key_mismatches++;
> - report_fail("page %d expected_key=0x%x actual_key=0x%x", i, expected_key.val, actual_key.val);
> + result.expected_key.val = expected_key.val;
> + result.actual_key.val = actual_key.val;
> + result.page_mismatch_idx = i;
> + result.page_mismatch_addr = (unsigned long)cur_page;
> + return result;
> }
> }
>
> - report(!key_mismatches, "skeys after migration match");
> + result.verify_failed = false;
> + return result;
> +}
> +
> +static void report_verify_result(struct verify_result * const result)
> +{
> + if (result->verify_failed)
> + report_fail("page skey mismatch: first page idx = %lu, addr = 0x%lx, "
> + "expected_key = 0x%x, actual_key = 0x%x",
> + result->page_mismatch_idx, result->page_mismatch_addr,
> + result->expected_key.val, result->actual_key.val);
> + else
> + report_pass("skeys match");
> +}
> +
> +static void test_skey_migration_sequential(void)
> +{
> + report_prefix_push("sequential");
> +
> + set_test_pattern(0);
> +
> + migrate_once();
> +
> + result = verify_test_pattern(0);
> + report_verify_result(&result);
> +
> + report_prefix_pop();
> +}
> +
> +static void set_skeys_thread(void)
> +{
> + while (!READ_ONCE(thread_should_exit)) {
> + set_test_pattern(thread_iters);
> +
> + result = verify_test_pattern(thread_iters);
> +
> + /*
> + * 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++;
> +
> + if (result.verify_failed)
> + break;
> + }
> +
> + WRITE_ONCE(thread_exited, 1);
> +}
> +
> +static void test_skey_migration_parallel(void)
> +{
> + report_prefix_push("parallel");
> +
> + if (smp_query_num_cpus() == 1) {
> + report_skip("need at least 2 cpus for this test");
> + goto error;
> + }
> +
> + smp_cpu_setup(1, PSW_WITH_CUR_MASK(set_skeys_thread));
> +
> + migrate_once();
> +
> + WRITE_ONCE(thread_should_exit, 1);
> +
> + while (!READ_ONCE(thread_exited))
> + ;
> +
> + /* Ensure we read result and thread_iters below from memory after thread exited */
> + mb();
> + report_info("thread completed %u iterations", thread_iters);
> +
> + report_prefix_push("during migration");
> + report_verify_result(&result);
> + report_prefix_pop();
> +
> + /*
> + * Verification of skeys 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 skeys which might not have been migrated
> + * correctly.
> + */
> + report_prefix_push("after migration");
> + assert(thread_iters > 0);
> + result = verify_test_pattern(thread_iters - 1);
> + report_verify_result(&result);
> + report_prefix_pop();
> +
> +error:
> + report_prefix_pop();
> +}
> +
> +static void print_usage(void)
> +{
> + report_info("Usage: migration-skey [--parallel|--sequential]");
> +}
> +
> +static void parse_args(int argc, char **argv)
> +{
> + if (argc < 2) {
> + /* default to sequential since it only needs one cpu */
> + arg_test_to_run = TEST_SEQUENTIAL;
> + return;
> + }
> +
> + if (!strcmp("--parallel", argv[1]))
> + arg_test_to_run = TEST_PARALLEL;
> + else if (!strcmp("--sequential", argv[1]))
> + arg_test_to_run = TEST_SEQUENTIAL;
> + else
> + arg_test_to_run = TEST_INVALID;
> }
>
> -int main(void)
> +int main(int argc, char **argv)
> {
> report_prefix_push("migration-skey");
>
> - if (test_facility(169))
> + if (test_facility(169)) {
> report_skip("storage key removal facility is active");
> - else
> - test_migration();
> + goto error;
> + }
>
> - migrate_once();
> + parse_args(argc, argv);
> +
> + switch (arg_test_to_run) {
> + case TEST_SEQUENTIAL:
> + test_skey_migration_sequential();
> + break;
> + case TEST_PARALLEL:
> + test_skey_migration_parallel();
> + break;
> + default:
> + print_usage();
> + break;
> + }
>
> +error:
> + migrate_once();
> report_prefix_pop();
> return report_summary();
> }
> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index 3caf81eda396..d97eb5e943c8 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -185,10 +185,6 @@ smp = 2
> file = migration-cmm.elf
> groups = migration
>
> -[migration-skey]
> -file = migration-skey.elf
> -groups = migration
> -
> [panic-loop-extint]
> file = panic-loop-extint.elf
> groups = panic
> @@ -208,3 +204,14 @@ groups = migration
> [exittime]
> file = exittime.elf
> smp = 2
> +
> +[migration-skey-sequential]
> +file = migration-skey.elf
> +groups = migration
> +extra_params = -append '--sequential'
> +
> +[migration-skey-parallel]
> +file = migration-skey.elf
> +smp = 2
> +groups = migration
> +extra_params = -append '--parallel'
