Re: [kvm-unit-tests PATCH v2 2/3] s390x: skrf: Add exception new skey test and add test to unittests.cfg

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

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On 7/27/20 2:20 PM, Thomas Huth wrote:
> On 27/07/2020 11.54, Janosch Frank wrote:
>> When an exception new psw with a storage key in its mask is loaded
>> from lowcore, a specification exception is raised. This differs from
>> the behavior when trying to execute skey related instructions, which
>> will result in special operation exceptions.
>>
>> Also let's add the test unittests.cfg so it is run more often.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
>> ---
>>  s390x/skrf.c        | 80 +++++++++++++++++++++++++++++++++++++++++++++
>>  s390x/unittests.cfg |  4 +++
>>  2 files changed, 84 insertions(+)
>>
>> diff --git a/s390x/skrf.c b/s390x/skrf.c
>> index 9cae589..fe78711 100644
>> --- a/s390x/skrf.c
>> +++ b/s390x/skrf.c
>> @@ -11,12 +11,16 @@
>>   */
>>  #include <libcflat.h>
>>  #include <asm/asm-offsets.h>
>> +#include <asm-generic/barrier.h>
>>  #include <asm/interrupt.h>
>>  #include <asm/page.h>
>>  #include <asm/facility.h>
>>  #include <asm/mem.h>
>> +#include <asm/sigp.h>
>> +#include <smp.h>
>>  
>>  static uint8_t pagebuf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
>> +static int testflag = 0;
>>  
>>  static void test_facilities(void)
>>  {
>> @@ -106,6 +110,81 @@ static void test_tprot(void)
>>  	report_prefix_pop();
>>  }
>>  
>> +static void wait_for_flag(void)
>> +{
>> +	while (!testflag)
>> +		mb();
>> +}
>> +
>> +static void set_flag(int val)
>> +{
>> +	mb();
>> +	testflag = val;
>> +	mb();
>> +}
>> +
>> +static void ecall_cleanup(void)
>> +{
>> +	struct lowcore *lc = (void *)0x0;
>> +
>> +	lc->ext_new_psw.mask = 0x0000000180000000UL;
>> +	lc->sw_int_crs[0] = 0x0000000000040000;
>> +
>> +	/*
>> +	 * PGM old contains the ext new PSW, we need to clean it up,
>> +	 * so we don't get a special operation exception on the lpswe
>> +	 * of pgm old.
>> +	 */
>> +	lc->pgm_old_psw.mask = 0x0000000180000000UL;
>> +	lc->pgm_old_psw.addr = (unsigned long)wait_for_flag;
> 
> I don't quite understand why you are using wait_for_flag here? Won't
> that function return immediately due to the set_flag(1) below? And if it
> returns, where does the cpu continue to exec code in that case? Wouldn't
> it be better to leave the .addr unchanged, so that the CPU returns to
> the endless loop in smp_cpu_setup_state ?

That's a valid point, will change

> 
>  Thomas
> 
> 
>> +	check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
>> +	set_flag(1);
>> +}
>> +
>> +/* Set a key into the external new psw mask and open external call masks */
>> +static void ecall_setup(void)
>> +{
>> +	struct lowcore *lc = (void *)0x0;
>> +	uint64_t mask;
>> +
>> +	register_pgm_int_func(ecall_cleanup);
>> +	expect_pgm_int();
>> +	/* Put a skey into the ext new psw */
>> +	lc->ext_new_psw.mask = 0x00F0000180000000UL;
>> +	/* Open up ext masks */
>> +	ctl_set_bit(0, 13);
>> +	mask = extract_psw_mask();
>> +	mask |= PSW_MASK_EXT;
>> +	load_psw_mask(mask);
>> +	/* Tell cpu 0 that we're ready */
>> +	set_flag(1);
>> +}
>> +
>> +static void test_exception_ext_new(void)
>> +{
>> +	struct psw psw = {
>> +		.mask = extract_psw_mask(),
>> +		.addr = (unsigned long)ecall_setup
>> +	};
>> +
>> +	report_prefix_push("exception external new");
>> +	if (smp_query_num_cpus() < 2) {
>> +		report_skip("Need second cpu for exception external new test.");
>> +		report_prefix_pop();
>> +		return;
>> +	}
>> +
>> +	smp_cpu_setup(1, psw);
>> +	wait_for_flag();
>> +	set_flag(0);
>> +
>> +	sigp(1, SIGP_EXTERNAL_CALL, 0, NULL);
>> +	wait_for_flag();
>> +	smp_cpu_stop(1);
>> +	report_prefix_pop();
>> +}
>> +
>>  int main(void)
>>  {
>>  	report_prefix_push("skrf");
>> @@ -121,6 +200,7 @@ int main(void)
>>  	test_mvcos();
>>  	test_spka();
>>  	test_tprot();
>> +	test_exception_ext_new();
>>  
>>  done:
>>  	report_prefix_pop();
>> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
>> index 0f156af..b35269b 100644
>> --- a/s390x/unittests.cfg
>> +++ b/s390x/unittests.cfg
>> @@ -88,3 +88,7 @@ extra_params = -m 3G
>>  [css]
>>  file = css.elf
>>  extra_params = -device virtio-net-ccw
>> +
>> +[skrf]
>> +file = skrf.elf
>> +smp = 2
>>
> 



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