Re: [Qemu-devel] [PATCH v2 03/29] target/s390x: implement local-TLB-clearing in IPTE

[Thomas Huth <thuth@redhat.com>]

On 30.05.2017 13:18, Aurelien Jarno wrote:
> On 2017-05-30 11:01, Thomas Huth wrote:
>> On 29.05.2017 21:24, Aurelien Jarno wrote:
>>> And at the same time make IPTE SMP aware.
>>>
>>> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
>>> ---
>>>  target/s390x/helper.h     |  2 +-
>>>  target/s390x/mem_helper.c | 19 ++++++++++++-------
>>>  target/s390x/translate.c  |  6 +++++-
>>>  3 files changed, 18 insertions(+), 9 deletions(-)
>> [...]
>>> @@ -1092,13 +1091,19 @@ void HELPER(ipte)(CPUS390XState *env, uint64_t pto, uint64_t vaddr)
>>>  
>>>      /* XXX we exploit the fact that Linux passes the exact virtual
>>>         address here - it's not obliged to! */
>>> -    tlb_flush_page(cs, page);
>>> +    /* XXX: the LC bit should be considered as 0 if the local-TLB-clearing
>>> +       facility is not installed.  */
>>
>> That should be easy, I think:
>>
>>     if (!s390_has_feat(S390_FEAT_LOCAL_TLB_CLEARING)) {
>>         m4 = 0;
>>     }
> 
> I agree, it should be easy to implement. The reason I haven't implemented
> it is that we currently don't have a good model for the TCG CPU, so we
> don't have a way to easily enable it or not (though that is changing a
> bit with your later patches). In practice we expose supported features
> through STFL/SFTLE, but we don't do any check to see if the features or
> instructions are enable or not.

OK, fair, ... and your patch clearly marks this spot with an XXX, so we
can revise this later. So:

Reviewed-by: Thomas Huth <thuth@redhat.com>