Re: [kvm-unit-tests PATCH v1 2/2] s390x: add migration test for storage keys

[Janosch Frank <frankja@linux.ibm.com>]

On 5/12/22 16:01, Nico Boehr wrote:
> Upon migration, we expect storage keys being set by the guest to be preserved,
> so add a test for 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
> the access key in the PSW doesn't match.
> 
> TCG currently doesn't implement key-controlled protection, see
> target/s390x/mmu_helper.c, function mmu_handle_skey(), hence add the relevant
> tests as xfails.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>   s390x/Makefile         |  1 +
>   s390x/migration-skey.c | 98 ++++++++++++++++++++++++++++++++++++++++++
>   s390x/unittests.cfg    |  4 ++
>   3 files changed, 103 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..6f3053d8ab40
> --- /dev/null
> +++ b/s390x/migration-skey.c
> @@ -0,0 +1,98 @@
> +/* 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, mismatching_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);
> +		expected_key.val = i * 2;
> +
> +		/* ignore reference bit */
> +		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);
> +
> +		/* ensure access key doesn't match storage key and is never zero */
> +		mismatching_key.str.acc = expected_key.str.acc < 15 ? expected_key.str.acc + 1 : 1;
> +		*page = 0xff;
> +
> +		expect_pgm_int();
> +		asm volatile (
> +			/* set access key */
> +			"spka 0(%[mismatching_key])\n"
> +			/* try to write page */
> +			"mvi 0(%[page]), 42\n"
> +			/* reset access key */
> +			"spka 0\n"
> +			:
> +			: [mismatching_key] "a"(mismatching_key.val),
> +			  [page] "a"(page)
> +			: "memory"
> +		);
> +		check_pgm_int_code_xfail(host_is_tcg(), PGM_INT_CODE_PROTECTION);

What's the expected pgm code?
Is it 0 because no pgm was injected?