Re: [kvm-unit-tests PATCH] s390x: Add strict mode to specification exception interpretation test

[Thomas Huth <thuth@redhat.com>]

On 25/11/2021 15.47, Janis Schoetterl-Glausch wrote:
> While specification exception interpretation is not required to occur,
> it can be useful for automatic regression testing to fail the test if it
> does not occur.
> Add a `--strict` argument to enable this.

Thank you very much for adding this!

Some comments below...

> `--strict` takes a list of machine types (as reported by STIDP)
> for which to enable strict mode, for example
> `--strict 8562,8561,3907,3906,2965,2964`
> will enable it for models z15 - z13.
> Alternatively, strict mode can be enabled for all but the listed machine
> types by prefixing the list with a `!`, for example
> `--strict !1090,1091,2064,2066,2084,2086,2094,2096,2097,2098,2817,2818,2827,2828`
> will enable it for z/Architecture models except those older than z13.
> 
> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> ---
> 
> Apparently my message with inline patch did not make it to the mailing
> list for some reason, so here's the patch again.
> 
>   s390x/spec_ex-sie.c | 59 ++++++++++++++++++++++++++++++++++++++++-----
>   1 file changed, 53 insertions(+), 6 deletions(-)
> 
> diff --git a/s390x/spec_ex-sie.c b/s390x/spec_ex-sie.c
> index 5dea411..9a063f9 100644
> --- a/s390x/spec_ex-sie.c
> +++ b/s390x/spec_ex-sie.c
> @@ -7,6 +7,7 @@
>    * specification exception interpretation is off/on.
>    */
>   #include <libcflat.h>
> +#include <stdlib.h>
>   #include <sclp.h>
>   #include <asm/page.h>
>   #include <asm/arch_def.h>
> @@ -36,7 +37,7 @@ static void reset_guest(void)
>   	vm.sblk->icptcode = 0;
>   }
>   
> -static void test_spec_ex_sie(void)
> +static void test_spec_ex_sie(bool strict)
>   {
>   	setup_guest();
>   
> @@ -61,14 +62,60 @@ static void test_spec_ex_sie(void)
>   	report(vm.sblk->icptcode == ICPT_PROGI
>   	       && vm.sblk->iprcc == PGM_INT_CODE_SPECIFICATION,
>   	       "Received specification exception intercept");
> -	if (vm.sblk->gpsw.addr == 0xdeadbeee)
> -		report_info("Interpreted initial exception, intercepted invalid program new PSW exception");
> -	else
> -		report_info("Did not interpret initial exception");
> +	{
> +		const char *msg;

Could you please move the variable declaration to the beginning of the 
function? Then you could get rid of the curly brackets and one level of 
indentation.

> +		msg = "Interpreted initial exception, intercepted invalid program new PSW exception";
> +		if (strict)
> +			report(vm.sblk->gpsw.addr == 0xdeadbeee, msg);
> +		else if (vm.sblk->gpsw.addr == 0xdeadbeee)
> +			report_info(msg);
> +		else
> +			report_info("Did not interpret initial exception");
> +	}
>   	report_prefix_pop();
>   	report_prefix_pop();
>   }
>   
> +static bool parse_strict(char **argv)
> +{
> +	uint16_t machine_id;
> +	char *list;
> +	bool ret;
> +
> +	if (!*argv)
> +		return false;

I think this works ok with out current implementation of argv, but that's an 
"inofficial" implementation detail, so in case this ever gets changed, it 
might be better to check argc first before dereferencing argv here ... so 
could you please add a check for argc, too?

> +	if (strcmp("--strict", *argv))
> +		return false;
> +
> +	machine_id = get_machine_id();
> +	list = argv[1];
> +	if (!list) {
> +		printf("No argument to --strict, ignoring\n");
> +		return false;

You could also support --strict without arguments - that could turn on the 
strict mode unconditionally, I think.

> +	}
> +	if (list[0] == '!') {
> +		ret = true;
> +		list++;
> +	} else
> +		ret = false;
> +	while (true) {
> +		long input = 0;
> +
> +		if (strlen(list) == 0)
> +			return ret;
> +		input = strtol(list, &list, 16);
> +		if (*list == ',')
> +			list++;
> +		else if (*list != '\0')
> +			break;
> +		if (input == machine_id)
> +			return !ret;
> +	}
> +	printf("Invalid --strict argument \"%s\", ignoring\n", list);
> +	return ret;
> +}
> +
>   int main(int argc, char **argv)
>   {
>   	if (!sclp_facilities.has_sief2) {
> @@ -76,7 +123,7 @@ int main(int argc, char **argv)
>   		goto out;
>   	}
>   
> -	test_spec_ex_sie();
> +	test_spec_ex_sie(parse_strict(argv + 1));
>   out:
>   	return report_summary();
>   }
> 

  Thomas