Re: [Qemu-devel] [PATCH RFC 3/3] s390x/tcg: make STFL store into the lowcore

[Thomas Huth]

On 27.09.2017 20:46, David Hildenbrand wrote:
> On 27.09.2017 19:52, Richard Henderson wrote:
>> On 09/27/2017 10:00 AM, David Hildenbrand wrote:
>>> Using virtual memory access is wrong and will soon include low-address
>>> protection checks, which is to be bypassed for STFL.
>>>
>>> This was originally part of a bigger STFL(E) refactoring.
>>>
>>> Signed-off-by: David Hildenbrand <address@hidden>
>>> ---
>>>  target/s390x/helper.h      | 2 +-
>>>  target/s390x/misc_helper.c | 7 ++++++-
>>>  2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> Need to sort this patch first, so that the series is bisectable.
> 
> Right, this should become #2.
> 
>>
>>>  DEF_HELPER_FLAGS_2(sfpc, TCG_CALL_NO_RWG, void, env, i64)
>>>  DEF_HELPER_FLAGS_2(sfas, TCG_CALL_NO_WG, void, env, i64)
>>>  DEF_HELPER_FLAGS_1(popcnt, TCG_CALL_NO_RWG_SE, i64, i64)
>>> -DEF_HELPER_FLAGS_1(stfl, TCG_CALL_NO_RWG, void, env)
>>>  DEF_HELPER_2(stfle, i32, env, i64)
>>>  DEF_HELPER_FLAGS_2(lpq, TCG_CALL_NO_WG, i64, env, i64)
>>>  DEF_HELPER_FLAGS_4(stpq, TCG_CALL_NO_WG, void, env, i64, i64, i64)
>>> @@ -153,6 +152,7 @@ DEF_HELPER_FLAGS_3(sturg, TCG_CALL_NO_WG, void, env, 
>>> i64, i64)
>>>  DEF_HELPER_1(per_check_exception, void, env)
>>>  DEF_HELPER_FLAGS_3(per_branch, TCG_CALL_NO_RWG, void, env, i64, i64)
>>>  DEF_HELPER_FLAGS_2(per_ifetch, TCG_CALL_NO_RWG, void, env, i64)
>>> +DEF_HELPER_FLAGS_1(stfl, TCG_CALL_NO_RWG, void, env)
>>>  
>>
>> Why?  Otherwise,
> 
> struct LowCore is only available for !CONFIG_USER_ONLY. Therefore I also
> have to move the helper declaration into !CONFIG_USER_ONLY.

You should mention that in the patch description, that it is a
privileged instruction and thus you also mark it here accordingly.

With that update:

Reviewed-by: Thomas Huth <address@hidden>