Re: [kvm-unit-tests PATCH v4 6/8] s390x: Add more tests for STSCH

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

On 2/24/22 16:43, Nico Boehr wrote:
> css_lib extensively uses STSCH, but two more cases deserve their own
> tests:
> 
> - unaligned address for SCHIB. We check for misalignment by 1 and 2
>    bytes.
> - channel not operational
> - bit 47 in SID not set
> - bit 5 of PMCW flags.
>    As per the principles of operation, bit 5 of the PMCW flags shall be
>    ignored by msch and always stored as zero by stsch.
> 
>    Older QEMU versions require this bit to always be zero on msch,
>    which is why this test may fail. A fix is available in QEMU master
>    commit 2df59b73e086 ("s390x/css: fix PMCW invalid mask").
> 
> Here's the QEMU PMCW invalid mask fix: https://lists.nongnu.org/archive/html/qemu-s390x/2021-12/msg00100.html
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Acked-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>   s390x/css.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 82 insertions(+)
> 
> diff --git a/s390x/css.c b/s390x/css.c
> index 7fe5283c41d0..dd84e670ce99 100644
> --- a/s390x/css.c
> +++ b/s390x/css.c
> @@ -501,6 +501,86 @@ static void test_ssch(void)
>   	report_prefix_pop();
>   }
>   
> +static void test_stsch(void)
> +{
> +	const int align_to = 4;
> +	struct schib schib;
> +	int cc;
> +
> +	if (!test_device_sid) {
> +		report_skip("No device");
> +		return;
> +	}
> +
> +	report_prefix_push("Unaligned");
> +	for (int i = 1; i < align_to; i *= 2) {
> +		report_prefix_pushf("%d", i);
> +
> +		expect_pgm_int();
> +		stsch(test_device_sid, (struct schib *)(alignment_test_page + i));
> +		check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
> +
> +		report_prefix_pop();
> +	}
> +	report_prefix_pop();
> +
> +	report_prefix_push("Invalid subchannel number");
> +	cc = stsch(0x0001ffff, &schib);
> +	report(cc == 3, "Channel not operational");
> +	report_prefix_pop();
> +
> +	/*
> +	 * No matter if multiple-subchannel-set facility is installed, bit 47
> +	 * always needs to be 1.
> +	 */
> +	report_prefix_push("Bit 47 in SID is zero");
> +	expect_pgm_int();
> +	stsch(0x0000ffff, &schib);
> +	check_pgm_int_code(PGM_INT_CODE_OPERAND);
> +	report_prefix_pop();
> +}
> +
> +/*
> + * According to architecture MSCH does ignore bit 5 of the second word
> + * but STSCH will store bit 5 as zero.
> + */
> +static void test_pmcw_bit5(void)
> +{
> +	int cc;
> +	uint16_t old_pmcw_flags;
> +
> +	cc = stsch(test_device_sid, &schib);
> +	if (cc) {
> +		report_fail("stsch: sch %08x failed with cc=%d", test_device_sid, cc);
> +		return;
> +	}
> +	old_pmcw_flags = schib.pmcw.flags;
> +
> +	report_prefix_push("Bit 5 set");
> +
> +	schib.pmcw.flags = old_pmcw_flags | BIT(15 - 5);
> +	cc = msch(test_device_sid, &schib);
> +	report(!cc, "MSCH cc == 0");
> +
> +	cc = stsch(test_device_sid, &schib);
> +	report(!cc, "STSCH cc == 0");
> +	report(!(schib.pmcw.flags & BIT(15 - 5)), "STSCH PMCW Bit 5 is clear");
> +
> +	report_prefix_pop();
> +
> +	report_prefix_push("Bit 5 clear");
> +
> +	schib.pmcw.flags = old_pmcw_flags & ~BIT(15 - 5);
> +	cc = msch(test_device_sid, &schib);
> +	report(!cc, "MSCH cc == 0");
> +
> +	cc = stsch(test_device_sid, &schib);
> +	report(!cc, "STSCH cc == 0");
> +	report(!(schib.pmcw.flags & BIT(15 - 5)), "STSCH PMCW Bit 5 is clear");
> +
> +	report_prefix_pop();
> +}
> +
>   static struct {
>   	const char *name;
>   	void (*func)(void);
> @@ -516,6 +596,8 @@ static struct {
>   	{ "msch", test_msch },
>   	{ "stcrw", test_stcrw },
>   	{ "ssch", test_ssch },
> +	{ "stsch", test_stsch },
> +	{ "pmcw bit 5 ignored", test_pmcw_bit5 },
>   	{ NULL, NULL }
>   };
>