On 26.09.2012, at 21:25, Christian Borntraeger wrote:
> On 26/09/12 21:01, Alexander Graf wrote:
>>
>> On 26.09.2012, at 18:06, Christian Borntraeger wrote:
>>
>>> On 26/09/12 17:00, Alexander Graf wrote:
>>>
>>>>> +/* Provide information about the configuration, CPUs and storage */
>>>>> +static void read_SCP_info(SCCB *sccb)
>>>>> +{
>>>>> + ReadInfo *read_info = (ReadInfo *) sccb;
>>>>> + int shift = 0;
>>>>> +
>>>>> + while ((ram_size >> (20 + shift)) > 65535) {
>>>>> + shift++;
>>>>> + }
>>>>> + read_info->rnmax = cpu_to_be16(ram_size >> (20 + shift));
>>>>> + read_info->rnsize = 1 << shift;
>>>>
>>>> Any reason we can't just always expose rnmax2 and rnsize2 instead? This
>>>> way we're quite limited on the amount of RAM we can support, right?
>>>
>>> Well, we have 65535 * 256 * 1MB == 16TB which is ok for the next 2 or 3
>>> years I guess.
>>> There are actually some rules that decide about rnmax vs rnmax2 etc, and
>>> here
>>> the non-2 are appropriate. This might change for systems > 16TB or systems
>>> with memory hotplug,
>>> but I would prefer to use those for now. We will add the full logic in case
>>> we add memory
>>> hotplug.
>>
>> Fair enough :).
>>
>>>
>>>
>>> [...]
>>>
>>>>> + if (be16_to_cpu(work_sccb.h.length) < 8 ||
>>>>
>>>> sizeof(SCCBHeader)
>>>
>>> ok
>>>
>>>
>>>>
>>>>> + be16_to_cpu(work_sccb.h.length) > 4096) {
>>>>
>>>> SCCB_SIZE
>>>
>>> ok
>>>
>>>
>>>>> */
>>>>> -int sclp_service_call(CPUS390XState *env, uint32_t sccb, uint64_t code)
>>>>> +int sclp_service_call(uint32_t sccb, uint64_t code)
>>>>
>>>> Why not move the whole thing into sclp.c? The only thing remaining here
>>>> are a few sanity checks that would just as well work in generic sclp
>>>> handling code, right?
>>>
>>> The idea was two-fold:
>>> - to have one single place were we cross between target-s390x and hw
>>> (review feedback from the first series, originally we had all everything in
>>> sclp.c)
>>> - to have the checks that the CPU can do over there and the complex things
>>> that look into the sccb in sclp.c
>>>
>>> But we could certainly move that, your take
>>
>> I would still see both fulfilled by having the 2 condition checks in sclp.c.
>> Why don't we need them for kvm? Does kvm check them in the kernel?
>
> KVM needs the checks as well. Thats why kvm calls into sclp_service_call
> (like the tcg) and then evaluates the return value (like tcg).
> sclp_service_call is the only place that calls into hw/* code. If we move
> that code into sclp we have two places that call from target to hw/: kvm.c
> and op_helper.c (now misc_helper.c). But it really doesnt matter, so lets
> just move that code.
Ah! Yes, please just call into sclp.c from kvm.c :).
Alex
