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

Janosch Frank
2020-07-27T12:38:52Z

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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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