Re: [kvm-unit-tests PATCH v2 1/1] s390x: add migration test for storage keys

[Janis Schoetterl-Glausch <scgl@linux.ibm.com>]

On 5/16/22 11:07, Nico Boehr wrote:
> Upon migration, we expect storage keys being set by the guest to be preserved,
> so add a test for it.

"being set" implies that keys are set while the migration is going on.
That's not the case, is it?
> 
> We keep 128 pages and set predictable storage keys. Then, we migrate and check
> they can be read back and the respective access restrictions are in place when

... check that they ...

> the access key in the PSW doesn't match.

The latter half of the sentence doesn't apply anymore, now that you simplified the test.
So maybe something like: ... and check that they can be read back and match the value
originally set.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>  s390x/Makefile         |  1 +
>  s390x/migration-skey.c | 78 ++++++++++++++++++++++++++++++++++++++++++
>  s390x/unittests.cfg    |  4 +++
>  3 files changed, 83 insertions(+)
>  create mode 100644 s390x/migration-skey.c
> 
> diff --git a/s390x/Makefile b/s390x/Makefile
> index a8e04aa6fe4d..f8ea594b641d 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -32,6 +32,7 @@ tests += $(TEST_DIR)/epsw.elf
>  tests += $(TEST_DIR)/adtl-status.elf
>  tests += $(TEST_DIR)/migration.elf
>  tests += $(TEST_DIR)/pv-attest.elf
> +tests += $(TEST_DIR)/migration-skey.elf
> 
>  pv-tests += $(TEST_DIR)/pv-diags.elf
> 
> diff --git a/s390x/migration-skey.c b/s390x/migration-skey.c
> new file mode 100644
> index 000000000000..ee4622eb94ba
> --- /dev/null
> +++ b/s390x/migration-skey.c
> @@ -0,0 +1,78 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Storage Key migration tests
> + *
> + * Copyright IBM Corp. 2022
> + *
> + * Authors:
> + *  Nico Boehr <nrb@linux.ibm.com>
> + */
> +
> +#include <libcflat.h>
> +#include <asm/facility.h>
> +#include <asm/page.h>
> +#include <asm/mem.h>
> +#include <asm/interrupt.h>
> +#include <hardware.h>
> +
> +#define NUM_PAGES 128
> +static uint8_t pagebuf[NUM_PAGES][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
> +
> +static void test_migration(void)
> +{
> +	int i, key_to_set;
> +	uint8_t *page;
> +	union skey expected_key, actual_key;
> +
> +	for (i = 0; i < NUM_PAGES; i++) {
> +		/*
> +		 * Storage keys are 7 bit, lowest bit is always returned as zero
> +		 * by iske
> +		 */
> +		key_to_set = i * 2;
> +		set_storage_key(pagebuf[i], key_to_set, 1);
> +	}
> +
> +	puts("Please migrate me, then press return\n");
> +	(void)getchar();
> +
> +	for (i = 0; i < NUM_PAGES; i++) {
> +		report_prefix_pushf("page %d", i);
> +
> +		page = &pagebuf[i][0];
> +		actual_key.val = get_storage_key(page);

The page variable is kinda useless now, I'd just do get_storage_key(pagebuf[0]).
> +		expected_key.val = i * 2;
> +
> +		/* ignore reference bit */

Why? Are there any implicit references I'm missing?
> +		actual_key.str.rf = 0;
> +		expected_key.str.rf = 0;
> +
> +		report(actual_key.val == expected_key.val, "expected_key=0x%x actual_key=0x%x", expected_key.val, actual_key.val);
> +
> +		report_prefix_pop();
> +	}
> +}
> +
> +int main(void)
> +{
> +	report_prefix_push("migration-skey");
> +	if (test_facility(169)) {
> +		report_skip("storage key removal facility is active");
> +
> +		/*
> +		 * 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 altogether.
> +		 */
> +		puts("Please migrate me, then press return\n");
> +		(void)getchar();
> +
> +		goto done;
> +	}
> +
> +	test_migration();
> +
> +done:
> +	report_prefix_pop();
> +	return report_summary();
> +}
> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index b456b2881448..1e851d8e3dd8 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -176,3 +176,7 @@ extra_params = -cpu qemu,gs=off,vx=off
>  file = migration.elf
>  groups = migration
>  smp = 2
> +
> +[migration-skey]
> +file = migration-skey.elf
> +groups = migration