On 07.07.20 13:44, Cornelia Huck wrote:
> On Tue, 7 Jul 2020 12:42:05 +0200
> Thomas Huth <thuth@xxxxxxxxxx> wrote:
>
>> When running the kvm-unit-tests with TCG on s390x, the cpumodel test
>> always reports the error about the missing DFP (decimal floating point)
>> facility. This is kind of expected, since DFP is not required for
>> running Linux and thus nobody is really interested in implementing
>> this facility in TCG. Thus let's mark this as an expected error instead,
>> so that we can run the kvm-unit-tests also with TCG without getting
>> test failures that we do not care about.
>>
>> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
>> ---
>> v2:
>> - Rewrote the logic, introduced expected_tcg_fail flag
>> - Use manufacturer string instead of VM name to detect TCG
>>
>> s390x/cpumodel.c | 49 ++++++++++++++++++++++++++++++++++++++++++------
>> 1 file changed, 43 insertions(+), 6 deletions(-)
>
> (...)
>
>> +static bool is_tcg(void)
>> +{
>> + const char qemu_ebcdic[] = { 0xd8, 0xc5, 0xd4, 0xe4 };
>> + bool ret = false;
>> + uint8_t *buf;
>> +
>> + buf = alloc_page();
>> + if (!buf)
>> + return false;
>> +
>> + if (stsi(buf, 1, 1, 1)) {
>> + goto out;
>> + }
>
> This does an alloc_page() and a stsi() every time you call it...
>
>> +
>> + /*
>> + * If the manufacturer string is "QEMU" in EBCDIC, then we are on TCG
>> + * (otherwise the string is "IBM" in EBCDIC)
>> + */
>> + if (!memcmp(&buf[32], qemu_ebcdic, sizeof(qemu_ebcdic)))
>> + ret = true;
>> +out:
>> + free_page(buf);
>> + return ret;
>> +}
>> +
>> +
>> int main(void)
>> {
>> int i;
>> @@ -46,11 +81,13 @@ int main(void)
>>
>> report_prefix_push("dependency");
>
> ...so maybe cache the value for is_tcg() here instead of checking
> multiple times in the loop?
Maybe move it to common code and do the detection early during boot? The
n provide is_tcg() or sth. like that. Could be helpful in other context
maybe.
--
Thanks,
David / dhildenb
