Re: [Qemu-devel] [PATCH v3 29/29] tests/tcg: target/s390x: Test MVO

["Alex Bennée" <alex.bennee@linaro.org>]

David Hildenbrand <david@redhat.com> writes:

> On 18.09.19 11:47, Alex Bennée wrote:
>>
>> David Hildenbrand <david@redhat.com> writes:
>>
>>> Let's add the simple test based on the example from the PoP.
>>>
>>> Signed-off-by: David Hildenbrand <david@redhat.com>
>>> ---
>>>  tests/tcg/s390x/Makefile.target |  1 +
>>>  tests/tcg/s390x/mvo.c           | 25 +++++++++++++++++++++++++
>>>  2 files changed, 26 insertions(+)
>>>  create mode 100644 tests/tcg/s390x/mvo.c
>>>
>>> diff --git a/tests/tcg/s390x/Makefile.target b/tests/tcg/s390x/Makefile.target
>>> index 151dc075aa..6a3bfa8b29 100644
>>> --- a/tests/tcg/s390x/Makefile.target
>>> +++ b/tests/tcg/s390x/Makefile.target
>>> @@ -6,3 +6,4 @@ TESTS+=ipm
>>>  TESTS+=exrl-trt
>>>  TESTS+=exrl-trtr
>>>  TESTS+=pack
>>> +TESTS+=mvo
>>> diff --git a/tests/tcg/s390x/mvo.c b/tests/tcg/s390x/mvo.c
>>> new file mode 100644
>>> index 0000000000..5546fe2a97
>>> --- /dev/null
>>> +++ b/tests/tcg/s390x/mvo.c
>>> @@ -0,0 +1,25 @@
>>> +#include <stdint.h>
>>> +#include <stdio.h>
>>> +
>>> +int main(void)
>>> +{
>>> +    uint8_t dest[6] = {0xff, 0x77, 0x88, 0x99, 0x0c, 0xff};
>>> +    uint8_t src[5] = {0xee, 0x12, 0x34, 0x56, 0xee};
>>> +    uint8_t expected[6] = {0xff, 0x01, 0x23, 0x45, 0x6c, 0xff};
>>> +    int i;
>>> +
>>> +    asm volatile (
>>> +        "    mvo 0(4,%[dest]),0(3,%[src])\n"
>>> +        :
>>> +        : [dest] "d" (dest + 1),
>>> +          [src] "d" (src + 1)
>>> +        : "memory");
>>> +
>>> +    for (i = 0; i < sizeof(expected); i++) {
>>> +        if (dest[i] != expected[i]) {
>>> +            fprintf(stderr, "bad data\n");
>>> +            return 1;
>>> +        }
>>> +    }
>>> +    return 0;
>>> +}
>>
>> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>>
>> but...
>>
>> can this test be expanded to check the page cross cases that caused you
>> so much trouble to track down?
>
> I might add a MVC test that tries to reproduce this. But with
> speculative page faults and things like that it might not be very easy
> to reproduce. However, I can give it a try.

I may not be fully understanding the correct behaviour but wouldn't the
test be:

  * map two page's worth of address space
  * mprot(!write) the top page
  * attempt mvc based copy to mmap region (say p0+(PAGE_SIZE>>1) to p1+(PAGE_SIZE>>1))
  * catch the fault
  * check the bottom page wasn't written to

or does the test need to be lower level and run in kernel mode in
softmmu and catch the appropriate low level exceptions?

>
> Thanks!
>
>>
>> --
>> Alex Bennée
>>


--
Alex Bennée