On 07/07/2020 09.22, Cornelia Huck wrote:
> On Tue, 7 Jul 2020 07:56:19 +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.
>
> Checking for tcg seems reasonable.
>
>>
>> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
>> ---
>> s390x/cpumodel.c | 51 ++++++++++++++++++++++++++++++++++++++++++------
>> 1 file changed, 45 insertions(+), 6 deletions(-)
>>
>> diff --git a/s390x/cpumodel.c b/s390x/cpumodel.c
>> index 5d232c6..4310b92 100644
>> --- a/s390x/cpumodel.c
>> +++ b/s390x/cpumodel.c
>> @@ -11,6 +11,7 @@
>> */
>>
>> #include <asm/facility.h>
>> +#include <alloc_page.h>
>>
>> static int dep[][2] = {
>> /* from SA22-7832-11 4-98 facility indications */
>> @@ -38,6 +39,49 @@ static int dep[][2] = {
>> { 155, 77 },
>> };
>>
>> +/*
>> + * A hack to detect TCG (instead of KVM): QEMU uses "TCGguest" as guest
>> + * name by default when we are running with TCG (otherwise it's "KVMguest")
>
> The guest name can be overwritten; I think it would be better to check
> for something hardcoded.
>
> Maybe the manufacturer name in SYSIB 1.1.1? When running under tcg,
> it's always 'QEMU' (it's 'IBM' when running under KVM).
OK, I'll have a try.
>> + */
>> +static bool is_tcg(void)
>> +{
>> + bool ret = false;
>> + uint8_t *buf;
>> +
>> + buf = alloc_page();
>> + if (!buf)
>> + return false;
>> +
>> + if (stsi(buf, 3, 2, 2)) {
>> + goto out;
>> + }
>> +
>> + /* Does the name start with "TCG" in EBCDIC? */
>> + if (buf[2048] == 0x54 && buf[2049] == 0x43 && buf[2050] == 0x47)
>> + ret = true;
>> +
>> +out:
>> + free_page(buf);
>> + return ret;
>> +}
>> +
>> +static void check_dependency(int dep1, int dep2)
>
> <bikeshed>
> Can we find more speaking parameter names? facility/implied?
> </bikeshed>
That makes sense, indeed.
Thanks,
Thomas
